Struct AVAssetReaderOutputCaptionAdaptor

Source

pub struct AVAssetReaderOutputCaptionAdaptor { /* private fields */ }

Available on crate feature AVAssetReaderOutput only.

Expand description

Apple’s documentation

Implementations§

Source §

pub unsafe fn assetReaderOutputCaptionAdaptorWithAssetReaderTrackOutput( track_output: &AVAssetReaderTrackOutput, ) -> Retained<Self>

Creates a new caption adaptor for reading from the given track output.

Parameter trackOutput: The track output from which to read captions.

Returns: A new instance of AVAssetReaderOutputCaptionAdaptor, configured to read captions from the given AVAssetReaderTrackOutput.

It is an error to pass nil to this method.

Source

pub unsafe fn initWithAssetReaderTrackOutput( this: Allocated<Self>, track_output: &AVAssetReaderTrackOutput, ) -> Retained<Self>

Creates a new caption adaptor for reading from the given track output.

Parameter trackOutput: The track output from which to read captions.

Returns: A new instance of AVAssetReaderOutputCaptionAdaptor, configured to read captions from the given AVAssetReaderTrackOutput.

It is an error to pass nil to this method.

Source

pub unsafe fn assetReaderTrackOutput( &self, ) -> Retained<AVAssetReaderTrackOutput>

The track output used to create the receiver.

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pub unsafe fn nextCaptionGroup(&self) -> Option<Retained<AVCaptionGroup>>

Available on crate feature AVCaptionGroup only.

Returns the next caption.

Returns: An instance of AVCaption representing the next caption.

The method returns the next caption group.

This method throws an exception if the track output is not attached to an asset reader and reading has not yet begun.

Source

pub unsafe fn captionsNotPresentInPreviousGroupsInCaptionGroup( &self, caption_group: &AVCaptionGroup, ) -> Retained<NSArray<AVCaption>>

Available on crate features AVCaption and AVCaptionGroup only.

Returns the set of captions that are present in the given group but were not present in any group previously vended by calls to -nextCaptionGroup: on the receiver.

Parameter captionGroup: The group containing the captions of interest.

Returns: An array of AVCaption objects.

The returned array contains the set of captions in the given group whose time ranges have the same start time as the group. This method is provided as a convenience for clients who want to process captions one-by-one and do not need a complete view of the set of captions active at a given time.

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impl AVAssetReaderOutputCaptionAdaptor

AVAssetReaderCaptionValidation.

Category of AVAssetReaderOutputCaptionAdaptor for caption validation handling

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pub unsafe fn validationDelegate( &self, ) -> Option<Retained<ProtocolObject<dyn AVAssetReaderCaptionValidationHandling>>>

Register caption validation handling callback protocol to the caption adaptor.

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pub unsafe fn setValidationDelegate( &self, validation_delegate: Option<&ProtocolObject<dyn AVAssetReaderCaptionValidationHandling>>, )

Setter for validationDelegate.

This is a weak property.

Methods from Deref<Target = NSObject>§

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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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());

Source

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.

Source

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`
    }
}