Struct AVSampleBufferDisplayLayer 

pub struct AVSampleBufferDisplayLayer { /* private fields */ }

Available on crate feature AVSampleBufferDisplayLayer and crate feature objc2-quartz-core and non-watchOS only.

Apple’s documentation

Implementations

impl AVSampleBufferDisplayLayer

pub unsafe fn controlTimebase(&self) -> Option<Retained<CMTimebase>>

Available on crate feature objc2-core-media only.

The layer’s control timebase, which governs how time stamps are interpreted.

By default, this property is NULL, in which case time stamps will be interpreted according to the host time clock (mach_absolute_time with the appropriate timescale conversion; this is the same as Core Animation’s CACurrentMediaTime). With no control timebase, once frames are enqueued, it is not possible to adjust exactly when they are displayed.

If a non-NULL control timebase is set, it will be used to interpret time stamps. You can control the timing of frame display by setting the rate and time of the control timebase. If you are synchronizing video to audio, you can use a timebase whose source clock is a CMAudioDeviceClock for the appropriate audio device to prevent drift.

Note that prior to OSX 10.10 and iOS 8.0, the control timebase could not be changed after enqueueSampleBuffer: was called. As of OSX 10.10 and iOS 8.0, the control timebase may be changed at any time.

pub unsafe fn setControlTimebase(&self, control_timebase: Option<&CMTimebase>)

Available on crate feature objc2-core-media only.

Setter for controlTimebase.

pub unsafe fn videoGravity(&self) -> Retained<AVLayerVideoGravity>

Available on crate feature AVAnimation only.

A string defining how the video is displayed within an AVSampleBufferDisplayLayer bounds rect.

Options are AVLayerVideoGravityResizeAspect, AVLayerVideoGravityResizeAspectFill and AVLayerVideoGravityResize. AVLayerVideoGravityResizeAspect is default. See <AVFoundation /AVAnimation.h> for a description of these options.

pub unsafe fn setVideoGravity(&self, video_gravity: &AVLayerVideoGravity)

Available on crate feature AVAnimation only.

Setter for videoGravity.

This is copied when set.

pub unsafe fn isReadyForDisplay(&self) -> bool

Boolean indicating that the first video frame has been made ready for display.

Use this property as an indicator of when best to show or animate-in an AVSampleBufferDisplayLayer into view. An AVSampleBufferDisplayLayer may be displayed, or made visible, while this property is NO, however the layer will not have any user-visible content until the value becomes YES. Note that if an animation is added to an AVSampleBufferDisplayLayer before it becomes readyForDisplay the video image displayed inside might not animate with the receiver. readyForDisplay will change to NO when the layer can no longer display frames. readyForDisplay will be YES when the first video frame has been made ready for display. This property is not key-value observable. AVSampleBufferDisplayLayerReadyForDisplayDidChangeNotification is posted when this value changes.

impl AVSampleBufferDisplayLayer

Methods declared on superclass CALayer.

pub unsafe fn layer() -> Retained<Self>

Layer creation and initialization. *

pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

pub unsafe fn initWithLayer( this: Allocated<Self>, layer: &AnyObject, ) -> Retained<Self>

Safety

layer should be of the correct type.

impl AVSampleBufferDisplayLayer

Methods declared on superclass NSObject.

pub unsafe fn new() -> Retained<Self>

impl AVSampleBufferDisplayLayer

AVSampleBufferDisplayLayerQueueManagement.

pub unsafe fn timebase(&self) -> Retained<CMTimebase>

👎Deprecated: Use sampleBufferRenderer’s timebase instead

Available on crate feature objc2-core-media only.

The renderer’s timebase, which governs how time stamps are interpreted.

The timebase is used to interpret time stamps.

The timebase is read-only. Use the AVSampleBufferRenderSynchronizer to set the rate or time.

pub unsafe fn status(&self) -> AVQueuedSampleBufferRenderingStatus

👎Deprecated: Use sampleBufferRenderer’s status instead

Available on crate feature AVQueuedSampleBufferRendering only.

The ability of the display layer to be used for enqueuing sample buffers.

The value of this property is an AVQueuedSampleBufferRenderingStatus that indicates whether the receiver can be used for enqueuing and rendering sample buffers. When the value of this property is AVQueuedSampleBufferRenderingStatusFailed, clients can check the value of the error property to determine the failure. To resume rendering sample buffers using the display layer after a failure, clients must first reset the status to AVQueuedSampleBufferRenderingStatusUnknown. This can be achieved by invoking -flush on the display layer.

This property is key value observable.

pub unsafe fn error(&self) -> Option<Retained<NSError>>

👎Deprecated: Use sampleBufferRenderer’s error instead

If the display layer’s status is AVQueuedSampleBufferRenderingStatusFailed, this describes the error that caused the failure.

The value of this property is an NSError that describes what caused the display layer to no longer be able to enqueue sample buffers. If the status is not AVQueuedSampleBufferRenderingStatusFailed, the value of this property is nil.

pub unsafe fn enqueueSampleBuffer(&self, sample_buffer: &CMSampleBuffer)

👎Deprecated: Use sampleBufferRenderer’s enqueueSampleBuffer: instead

Available on crate feature objc2-core-media only.

Sends a sample buffer for display.

If sampleBuffer has the kCMSampleAttachmentKey_DoNotDisplay attachment set to kCFBooleanTrue, the frame will be decoded but not displayed. Otherwise, if sampleBuffer has the kCMSampleAttachmentKey_DisplayImmediately attachment set to kCFBooleanTrue, the decoded image will be displayed as soon as possible, replacing all previously enqueued images regardless of their timestamps. Otherwise, the decoded image will be displayed at sampleBuffer’s output presentation timestamp, as interpreted by the control timebase (or the mach_absolute_time timeline if there is no control timebase).

To schedule the removal of previous images at a specific timestamp, enqueue a marker sample buffer containing no samples, with the kCMSampleBufferAttachmentKey_EmptyMedia attachment set to kCFBooleanTrue.

IMPORTANT NOTE: attachments with the kCMSampleAttachmentKey_ prefix must be set via CMSampleBufferGetSampleAttachmentsArray and CFDictionarySetValue. Attachments with the kCMSampleBufferAttachmentKey_ prefix must be set via CMSetAttachment.

IMPORTANT NOTE: When using CMSampleBuffers that wrap CVPixelBuffer, it is important that such CVPixelBuffers be IOSurface-backed. CoreVideo allocates IOSurface-backed CVPixelBuffers when the pixel buffer attribute dictionary passed to CVPixelBufferPoolCreate contains an entry with key kCVPixelBufferIOSurfacePropertiesKey and value being a dictionary (which can be an empty dictionary).

The combination of either a non-NULL controlTimebase or an AVSampleBufferRenderSynchronizer with the use of kCMSampleAttachmentKey_DisplayImmediately as an attachment to the CMSampleBuffers that are enqueued for display is not recommended.

pub unsafe fn flush(&self)

👎Deprecated: Use sampleBufferRenderer’s flush instead

Instructs the layer to discard pending enqueued sample buffers.

It is not possible to determine which sample buffers have been decoded, so the next frame passed to enqueueSampleBuffer: should be an IDR frame (also known as a key frame or sync sample).

pub unsafe fn flushAndRemoveImage(&self)

👎Deprecated: Use sampleBufferRenderer’s flushWithRemovalOfDisplayedImage:completionHandler: instead

Instructs the layer to discard pending enqueued sample buffers and remove any currently displayed image.

It is not possible to determine which sample buffers have been decoded, so the next frame passed to enqueueSampleBuffer: should be an IDR frame (also known as a key frame or sync sample).

pub unsafe fn requiresFlushToResumeDecoding(&self) -> bool

👎Deprecated: Use sampleBufferRenderer’s requiresFlushToResumeDecoding instead

Indicates that the receiver is in a state where it requires a call to -flush to continue decoding frames.

When the application enters a state where use of video decoder resources is not permissible, the value of this property changes to YES along with the display layer’s status changing to AVQueuedSampleBufferRenderingStatusFailed. To resume rendering sample buffers using the display layer after this property’s value is YES, clients must first reset the display layer’s status to AVQueuedSampleBufferRenderingStatusUnknown. This can be achieved by invoking -flush on the display layer. Clients can track changes to this property via AVSampleBufferDisplayLayerRequiresFlushToResumeDecodingDidChangeNotification. This property is not key value observable.

pub unsafe fn isReadyForMoreMediaData(&self) -> bool

👎Deprecated: Use sampleBufferRenderer’s readyForMoreMediaData instead

Indicates the readiness of the layer to accept more sample buffers.

AVSampleBufferDisplayLayer keeps track of the occupancy levels of its internal queues for the benefit of clients that enqueue sample buffers from non-real-time sources – i.e., clients that can supply sample buffers faster than they are consumed, and so need to decide when to hold back.

Clients enqueueing sample buffers from non-real-time sources may hold off from generating or obtaining more sample buffers to enqueue when the value of readyForMoreMediaData is NO.

It is safe to call enqueueSampleBuffer: when readyForMoreMediaData is NO, but it is a bad idea to enqueue sample buffers without bound.

To help with control of the non-real-time supply of sample buffers, such clients can use -requestMediaDataWhenReadyOnQueue:usingBlock in order to specify a block that the layer should invoke whenever it’s ready for sample buffers to be appended.

The value of readyForMoreMediaData will often change from NO to YES asynchronously, as previously supplied sample buffers are decoded and displayed.

This property is not key value observable.

pub unsafe fn requestMediaDataWhenReadyOnQueue_usingBlock( &self, queue: &DispatchQueue, block: &DynBlock<dyn Fn()>, )

👎Deprecated: Use sampleBufferRenderer’s requestMediaDataWhenReadyOnQueue:usingBlock: instead

Available on crate features block2 and dispatch2 only.

Instructs the target to invoke a client-supplied block repeatedly, at its convenience, in order to gather sample buffers for display.

The block should enqueue sample buffers to the layer either until the layer’s readyForMoreMediaData property becomes NO or until there is no more data to supply. When the layer has decoded enough of the media data it has received that it becomes ready for more media data again, it will invoke the block again in order to obtain more. If this function is called multiple times, only the last call is effective. Call stopRequestingMediaData to cancel this request. Each call to requestMediaDataWhenReadyOnQueue:usingBlock: should be paired with a corresponding call to stopRequestingMediaData:. Releasing the AVSampleBufferDisplayLayer without a call to stopRequestingMediaData will result in undefined behavior.

Safety

• queue possibly has additional threading requirements.
• block block must be sendable.

pub unsafe fn stopRequestingMediaData(&self)

👎Deprecated: Use sampleBufferRenderer’s stopRequestingMediaData instead

Cancels any current requestMediaDataWhenReadyOnQueue:usingBlock: call.

This method may be called from outside the block or from within the block.

pub unsafe fn hasSufficientMediaDataForReliablePlaybackStart(&self) -> bool

👎Deprecated: Use sampleBufferRenderer’s hasSufficientMediaDataForReliablePlaybackStart instead

Indicates whether the enqueued media data meets the renderer’s preroll level.

Clients should fetch the value of this property to learn if the renderer has had enough media data enqueued to start playback reliably. Starting playback when this property is NO may prevent smooth playback following an immediate start.

impl AVSampleBufferDisplayLayer

AVSampleBufferDisplayLayerImageProtection.

pub unsafe fn preventsCapture(&self) -> bool

Indicates that image data should be protected from capture.

pub unsafe fn setPreventsCapture(&self, prevents_capture: bool)

Setter for preventsCapture.

impl AVSampleBufferDisplayLayer

AVSampleBufferDisplayLayerVideoDisplaySleepPrevention.

pub unsafe fn preventsDisplaySleepDuringVideoPlayback(&self) -> bool

Indicates whether video playback prevents display and device sleep.

Default is YES on iOS, tvOS and in Mac Catalyst apps. Default is NO on macOS. Setting this property to NO does not force the display to sleep, it simply stops preventing display sleep. Other apps or frameworks within your app may still be preventing display sleep for various reasons. Note: If sample buffers are being enqueued for playback at the user’s request, you should ensure that the value of this property is set to YES. If video is not being displayed as part of the user’s primary focus, you should ensure that the value of this property is set to NO.

pub unsafe fn setPreventsDisplaySleepDuringVideoPlayback( &self, prevents_display_sleep_during_video_playback: bool, )

Setter for preventsDisplaySleepDuringVideoPlayback.

impl AVSampleBufferDisplayLayer

AVSampleBufferDisplayLayerAutomaticBackgroundPrevention.

pub unsafe fn preventsAutomaticBackgroundingDuringVideoPlayback(&self) -> bool

Indicates whether video playback prevents the app from automatically getting backgrounded.

Default is YES. Setting this property to YES prevents an application that is playing video from automatically getting backgrounded. This property does not prevent the user from backgrounding the application. Note: If sample buffers are being enqueued for playback at the user’s request, you should ensure that the value of this property is set to YES. If video is not being displayed as part of the user’s primary focus, you should ensure that the value of this property is set to NO.

pub unsafe fn setPreventsAutomaticBackgroundingDuringVideoPlayback( &self, prevents_automatic_backgrounding_during_video_playback: bool, )

Setter for preventsAutomaticBackgroundingDuringVideoPlayback.

impl AVSampleBufferDisplayLayer

ProtectedContent.

pub unsafe fn outputObscuredDueToInsufficientExternalProtection(&self) -> bool

Whether or not decoded output is being obscured due to insufficient external protection.

The value of this property indicates whether the layer is purposefully obscuring its visual output because the requirement for an external protection mechanism is not met by the current device configuration. The change of this property can be observed through AVSampleBufferDisplayLayerOutputObscuredDueToInsufficientExternalProtectionDidChangeNotification

It is highly recommended that clients whose content requires external protection observe this property and set the playback rate to zero and display an appropriate user interface when the value changes to YES.

Note that the value of this property is dependent on the external protection requirements of the media being displayed by the layer. These requirements are inherent to the content itself and cannot be externally specified. If the content does not require external protection, the value of this property will be NO.

impl AVSampleBufferDisplayLayer

AVSampleBufferDisplayLayerRenderer.

pub unsafe fn sampleBufferRenderer( &self, ) -> Retained<AVSampleBufferVideoRenderer>

Available on crate feature AVSampleBufferVideoRenderer only.

An AVSampleBufferVideoRenderer instance that allows enqueuing sample buffers for rendering.

Although AVSampleBufferDisplayLayer conforms to the AVQueuedSampleBufferRendering protocol, the sampleBufferRenderer should be used to enqueue sample buffers. sampleBufferRenderer allows the client to safely enqueue sample buffers from a background thread. NOTE: Do not use AVSampleBufferDisplayLayer’s AVQueuedSampleBufferRendering functions when using sampleBufferRenderer.

Methods from Deref<Target = CALayer>

pub unsafe fn presentationLayer(&self) -> Option<Retained<CALayer>>

pub unsafe fn modelLayer(&self) -> Retained<CALayer>

pub fn shouldArchiveValueForKey(&self, key: &NSString) -> bool

pub fn isHidden(&self) -> bool

pub fn setHidden(&self, hidden: bool)

Setter for isHidden.

pub fn isDoubleSided(&self) -> bool

pub fn setDoubleSided(&self, double_sided: bool)

Setter for isDoubleSided.

pub fn isGeometryFlipped(&self) -> bool

pub fn setGeometryFlipped(&self, geometry_flipped: bool)

Setter for isGeometryFlipped.

pub fn contentsAreFlipped(&self) -> bool

pub fn superlayer(&self) -> Option<Retained<CALayer>>

pub fn removeFromSuperlayer(&self)

pub unsafe fn sublayers(&self) -> Option<Retained<NSArray<CALayer>>>

pub unsafe fn setSublayers(&self, sublayers: Option<&NSArray<CALayer>>)

Setter for sublayers.

This is copied when set.

pub fn addSublayer(&self, layer: &CALayer)

pub fn insertSublayer_atIndex(&self, layer: &CALayer, idx: u32)

pub fn insertSublayer_below(&self, layer: &CALayer, sibling: Option<&CALayer>)

pub fn insertSublayer_above(&self, layer: &CALayer, sibling: Option<&CALayer>)

pub unsafe fn replaceSublayer_with( &self, old_layer: &CALayer, new_layer: &CALayer, )

pub fn mask(&self) -> Option<Retained<CALayer>>

pub unsafe fn setMask(&self, mask: Option<&CALayer>)

Setter for mask.

pub fn masksToBounds(&self) -> bool

pub fn setMasksToBounds(&self, masks_to_bounds: bool)

Setter for masksToBounds.

pub unsafe fn contents(&self) -> Option<Retained<AnyObject>>

Layer content properties and methods. *

pub unsafe fn setContents(&self, contents: Option<&AnyObject>)

Setter for contents.

Safety

contents should be of the correct type.

pub fn contentsGravity(&self) -> Retained<NSString>

pub fn setContentsGravity(&self, contents_gravity: &NSString)

Setter for contentsGravity.

This is copied when set.

pub fn contentsFormat(&self) -> Retained<NSString>

pub fn setContentsFormat(&self, contents_format: &NSString)

Setter for contentsFormat.

This is copied when set.

pub fn wantsExtendedDynamicRangeContent(&self) -> bool

👎Deprecated: Use preferredDynamicRange instead

pub fn setWantsExtendedDynamicRangeContent( &self, wants_extended_dynamic_range_content: bool, )

👎Deprecated: Use preferredDynamicRange instead

Setter for wantsExtendedDynamicRangeContent.

pub fn toneMapMode(&self) -> Retained<NSString>

pub fn setToneMapMode(&self, tone_map_mode: &NSString)

Setter for toneMapMode.

This is copied when set.

pub fn preferredDynamicRange(&self) -> Retained<NSString>

pub fn setPreferredDynamicRange(&self, preferred_dynamic_range: &NSString)

Setter for preferredDynamicRange.

This is copied when set.

pub fn wantsDynamicContentScaling(&self) -> bool

pub fn setWantsDynamicContentScaling(&self, wants_dynamic_content_scaling: bool)

Setter for wantsDynamicContentScaling.

pub fn minificationFilter(&self) -> Retained<NSString>

pub fn setMinificationFilter(&self, minification_filter: &NSString)

Setter for minificationFilter.

This is copied when set.

pub fn magnificationFilter(&self) -> Retained<NSString>

pub fn setMagnificationFilter(&self, magnification_filter: &NSString)

Setter for magnificationFilter.

This is copied when set.

pub fn minificationFilterBias(&self) -> f32

pub fn setMinificationFilterBias(&self, minification_filter_bias: f32)

Setter for minificationFilterBias.

pub fn isOpaque(&self) -> bool

pub fn setOpaque(&self, opaque: bool)

Setter for isOpaque.

pub fn display(&self)

pub fn setNeedsDisplay(&self)

pub fn needsDisplay(&self) -> bool

pub fn displayIfNeeded(&self)

pub fn needsDisplayOnBoundsChange(&self) -> bool

pub fn setNeedsDisplayOnBoundsChange( &self, needs_display_on_bounds_change: bool, )

Setter for needsDisplayOnBoundsChange.

pub fn drawsAsynchronously(&self) -> bool

pub fn setDrawsAsynchronously(&self, draws_asynchronously: bool)

Setter for drawsAsynchronously.

pub fn edgeAntialiasingMask(&self) -> CAEdgeAntialiasingMask

pub fn setEdgeAntialiasingMask( &self, edge_antialiasing_mask: CAEdgeAntialiasingMask, )

Setter for edgeAntialiasingMask.

pub fn allowsEdgeAntialiasing(&self) -> bool

pub fn setAllowsEdgeAntialiasing(&self, allows_edge_antialiasing: bool)

Setter for allowsEdgeAntialiasing.

pub fn maskedCorners(&self) -> CACornerMask

pub fn setMaskedCorners(&self, masked_corners: CACornerMask)

Setter for maskedCorners.

pub fn cornerCurve(&self) -> Retained<NSString>

pub fn setCornerCurve(&self, corner_curve: &NSString)

Setter for cornerCurve.

This is copied when set.

pub fn opacity(&self) -> f32

pub fn setOpacity(&self, opacity: f32)

Setter for opacity.

pub fn allowsGroupOpacity(&self) -> bool

pub fn setAllowsGroupOpacity(&self, allows_group_opacity: bool)

Setter for allowsGroupOpacity.

pub fn compositingFilter(&self) -> Option<Retained<AnyObject>>

pub unsafe fn setCompositingFilter( &self, compositing_filter: Option<&AnyObject>, )

Setter for compositingFilter.

Safety

compositing_filter should be of the correct type.

pub fn filters(&self) -> Option<Retained<NSArray>>

pub unsafe fn setFilters(&self, filters: Option<&NSArray>)

Setter for filters.

This is copied when set.

Safety

filters generic should be of the correct type.

pub fn backgroundFilters(&self) -> Option<Retained<NSArray>>

pub unsafe fn setBackgroundFilters(&self, background_filters: Option<&NSArray>)

Setter for backgroundFilters.

This is copied when set.

Safety

background_filters generic should be of the correct type.

pub fn shouldRasterize(&self) -> bool

pub fn setShouldRasterize(&self, should_rasterize: bool)

Setter for shouldRasterize.

pub fn shadowOpacity(&self) -> f32

pub fn setShadowOpacity(&self, shadow_opacity: f32)

Setter for shadowOpacity.

pub fn autoresizingMask(&self) -> CAAutoresizingMask

Layout methods. *

pub fn setAutoresizingMask(&self, autoresizing_mask: CAAutoresizingMask)

Setter for autoresizingMask.

pub fn layoutManager( &self, ) -> Option<Retained<ProtocolObject<dyn CALayoutManager>>>

pub fn setLayoutManager( &self, layout_manager: Option<&ProtocolObject<dyn CALayoutManager>>, )

Setter for layoutManager.

pub fn setNeedsLayout(&self)

pub fn needsLayout(&self) -> bool

pub fn layoutIfNeeded(&self)

pub fn layoutSublayers(&self)

pub fn actionForKey( &self, event: &NSString, ) -> Option<Retained<ProtocolObject<dyn CAAction>>>

pub fn actions( &self, ) -> Option<Retained<NSDictionary<NSString, ProtocolObject<dyn CAAction>>>>

pub fn setActions( &self, actions: Option<&NSDictionary<NSString, ProtocolObject<dyn CAAction>>>, )

Setter for actions.

This is copied when set.

pub fn removeAllAnimations(&self)

pub fn removeAnimationForKey(&self, key: &NSString)

pub fn animationKeys(&self) -> Option<Retained<NSArray<NSString>>>

pub fn name(&self) -> Option<Retained<NSString>>

Miscellaneous properties. *

pub fn setName(&self, name: Option<&NSString>)

Setter for name.

This is copied when set.

pub fn delegate(&self) -> Option<Retained<ProtocolObject<dyn CALayerDelegate>>>

pub fn setDelegate( &self, delegate: Option<&ProtocolObject<dyn CALayerDelegate>>, )

Setter for delegate.

This is a weak property.

pub fn style(&self) -> Option<Retained<NSDictionary>>

pub unsafe fn setStyle(&self, style: Option<&NSDictionary>)

Setter for style.

This is copied when set.

Safety

style generic should be of the correct type.

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

pub unsafe fn get_ivar<T>(&self, name: &str) -> &T

where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

pub fn downcast_ref<T>(&self) -> Option<&T>

where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}

Trait Implementations

impl AVQueuedSampleBufferRendering for AVSampleBufferDisplayLayer

unsafe fn timebase(&self) -> Retained<CMTimebase>

where Self: Sized + Message,

Available on crate features AVQueuedSampleBufferRendering and objc2-core-media only.

The renderer’s timebase, which governs how time stamps are interpreted.

unsafe fn enqueueSampleBuffer(&self, sample_buffer: &CMSampleBuffer)

where Self: Sized + Message,

Available on crate features AVQueuedSampleBufferRendering and objc2-core-media only.

Sends a sample buffer in order to render its contents.

unsafe fn flush(&self)

where Self: Sized + Message,

Available on crate feature AVQueuedSampleBufferRendering only.

Instructs the receiver to discard pending enqueued sample buffers.

unsafe fn isReadyForMoreMediaData(&self) -> bool

where Self: Sized + Message,

Available on crate feature AVQueuedSampleBufferRendering only.

Indicates the readiness of the receiver to accept more sample buffers.

unsafe fn requestMediaDataWhenReadyOnQueue_usingBlock( &self, queue: &DispatchQueue, block: &DynBlock<dyn Fn()>, )

where Self: Sized + Message,

Available on crate features block2 and dispatch2 and AVQueuedSampleBufferRendering only.

Instructs the target to invoke a client-supplied block repeatedly, at its convenience, in order to gather sample buffers for playback.

unsafe fn stopRequestingMediaData(&self)

where Self: Sized + Message,

Available on crate feature AVQueuedSampleBufferRendering only.

Cancels any current requestMediaDataWhenReadyOnQueue:usingBlock: call.

unsafe fn hasSufficientMediaDataForReliablePlaybackStart(&self) -> bool

where Self: Sized + Message,

Available on crate feature AVQueuedSampleBufferRendering only.

Indicates whether the enqueued media data meets the renderer’s preroll level.

impl AsRef<AVSampleBufferDisplayLayer> for AVSampleBufferDisplayLayer

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AnyObject> for AVSampleBufferDisplayLayer

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<CALayer> for AVSampleBufferDisplayLayer

fn as_ref(&self) -> &CALayer

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for AVSampleBufferDisplayLayer

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AnyObject> for AVSampleBufferDisplayLayer

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<CALayer> for AVSampleBufferDisplayLayer

fn borrow(&self) -> &CALayer

Immutably borrows from an owned value.

impl Borrow<NSObject> for AVSampleBufferDisplayLayer

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl CAMediaTiming for AVSampleBufferDisplayLayer

fn speed(&self) -> f32

where Self: Sized + Message,

fn setSpeed(&self, speed: f32)

where Self: Sized + Message,

Setter for speed.

fn repeatCount(&self) -> f32

where Self: Sized + Message,

fn setRepeatCount(&self, repeat_count: f32)

where Self: Sized + Message,

Setter for repeatCount.

fn autoreverses(&self) -> bool

where Self: Sized + Message,

fn setAutoreverses(&self, autoreverses: bool)

where Self: Sized + Message,

Setter for autoreverses.

fn fillMode(&self) -> Retained<NSString>

where Self: Sized + Message,

fn setFillMode(&self, fill_mode: &NSString)

where Self: Sized + Message,

Setter for fillMode.

impl ClassType for AVSampleBufferDisplayLayer

const NAME: &'static str = "AVSampleBufferDisplayLayer"

The name of the Objective-C class that this type represents.

type Super = CALayer

The superclass of this class.

type ThreadKind = <<AVSampleBufferDisplayLayer as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl Debug for AVSampleBufferDisplayLayer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for AVSampleBufferDisplayLayer

type Target = CALayer

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for AVSampleBufferDisplayLayer

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for AVSampleBufferDisplayLayer

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSCoding for AVSampleBufferDisplayLayer

unsafe fn encodeWithCoder(&self, coder: &NSCoder)

where Self: Sized + Message,

Safety

unsafe fn initWithCoder( this: Allocated<Self>, coder: &NSCoder, ) -> Option<Retained<Self>>

where Self: Sized + Message,

Safety

impl NSObjectProtocol for AVSampleBufferDisplayLayer

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl NSSecureCoding for AVSampleBufferDisplayLayer

fn supportsSecureCoding() -> bool

where Self: Sized + ClassType,

impl PartialEq for AVSampleBufferDisplayLayer

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for AVSampleBufferDisplayLayer

const ENCODING_REF: Encoding = <CALayer as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for AVSampleBufferDisplayLayer

impl Eq for AVSampleBufferDisplayLayer