Struct AVPlayerItemTrack

Source

pub struct AVPlayerItemTrack { /* private fields */ }

Available on crate feature AVPlayerItemTrack only.

Expand description

An AVPlayerItemTrack carries a reference to an AVAssetTrack as well as presentation settings for that track.

Note that inspection of assets tracks is provided by AVAssetTrack. This class is intended to represent presentation state for a track of an asset that’s played by an AVPlayer and AVPlayerItem.

Implementations§

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impl AVPlayerItemTrack

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pub unsafe fn assetTrack(&self) -> Option<Retained<AVAssetTrack>>

Available on crate feature AVAssetTrack only.

Indicates the AVAssetTrack for which the AVPlayerItemTrack represents presentation state.

This property is not observable. Clients must serialize their access to the resulting AVAssetTrack and related objects on the associated AVPlayer’s notification queue. By default, this queue is the main queue.

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pub unsafe fn isEnabled(&self) -> bool

Indicates whether the track is enabled for presentation during playback.

Before macOS 13, iOS 16, tvOS 16, and watchOS 9, this property must be accessed on the main thread/queue.

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pub unsafe fn setEnabled(&self, enabled: bool)

Setter for isEnabled.

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pub unsafe fn currentVideoFrameRate(&self) -> c_float

If the media type of the assetTrack is AVMediaTypeVideo, indicates the current frame rate of the track as it plays, in units of frames per second. If the item is not playing, or if the media type of the track is not video, the value of this property is 0.

This property is not observable.

Before macOS 13, iOS 16, tvOS 16, and watchOS 9, this property must be accessed on the main thread/queue.

Source

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

If the media type of the assetTrack is AVMediaTypeVideo, specifies the handling of video frames that contain multiple fields.

A value of nil indicates default processing of video frames. If you want video fields to be deinterlaced, set videoFieldMode to AVPlayerItemTrackVideoFieldModeDeinterlaceFields. You can test whether video being played has multiple fields by examining the underlying AVAssetTrack’s format descriptions. See -[AVAssetTrack formatDescriptions] and, for video format descriptions, kCMFormatDescriptionExtension_FieldCount.

Before macOS 13, iOS 16, tvOS 16, and watchOS 9, this property must be accessed on the main thread/queue.

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pub unsafe fn setVideoFieldMode(&self, video_field_mode: Option<&NSString>)

Setter for videoFieldMode.

This is copied when set.

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impl AVPlayerItemTrack

Methods declared on superclass NSObject.

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

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pub unsafe fn new(mtm: MainThreadMarker) -> Retained<Self>

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`
    }
}