Struct AVAssetResourceLoader

Source

pub struct AVAssetResourceLoader { /* private fields */ }

Available on crate feature AVAssetResourceLoader only.

Expand description

Apple’s documentation

Implementations§

Source §

pub unsafe fn setDelegate_queue( &self, delegate: Option<&ProtocolObject<dyn AVAssetResourceLoaderDelegate>>, delegate_queue: Option<&DispatchQueue>, )

Available on crate feature dispatch2 only.

Sets the receiver’s delegate that will mediate resource loading and the dispatch queue on which delegate methods will be invoked.

Parameter delegate: An object conforming to the AVAssetResourceLoaderDelegate protocol.

Parameter delegateQueue: A dispatch queue on which all delegate methods will be invoked.

If you employ an AVAssetResourceLoader delegate that loads media data for playback, you should set the value of your AVPlayer’s automaticallyWaitsToMinimizeStalling property to NO. Allowing the value of automaticallyWaitsToMinimizeStalling to remain YES — its default value — when an AVAssetResourceLoader delegate is used for the loading of media data can result in poor start-up times for playback and poor recovery from stalls, because the behaviors provided by AVPlayer when automaticallyWaitsToMinimizeStalling has a value of YES depend on predictions of the future availability of media data that that do not function as expected when data is loaded via a client-controlled means, using the AVAssetResourceLoader delegate interface.

You can allow the value of automaticallyWaitsToMinimizeStalling to remain YES if you use an AVAssetResourceLoader delegate to manage content keys for FairPlay Streaming, to provide dynamically-generated master playlists for HTTP Live Streaming, or to respond to authentication challenges, but not to load media data for playback.

§Safety

delegate_queue possibly has additional threading requirements.

Source

pub unsafe fn delegate( &self, ) -> Option<Retained<ProtocolObject<dyn AVAssetResourceLoaderDelegate>>>

The receiver’s delegate.

The value of this property is an object conforming to the AVAssetResourceLoaderDelegate protocol. The delegate is set using the setDelegate:queue: method. The delegate is held using a zeroing-weak reference, so this property will have a value of nil after a delegate that was previously set has been deallocated.

Source

pub unsafe fn delegateQueue(&self) -> Option<Retained<DispatchQueue>>

Available on crate feature dispatch2 only.

The dispatch queue on which all delegate methods will be invoked.

The value of this property is a dispatch_queue_t. The queue is set using the setDelegate:queue: method.

Source §

impl AVAssetResourceLoader

AVAssetResourceLoaderContentKeySupport.

Source

pub unsafe fn preloadsEligibleContentKeys(&self) -> bool

When YES, eligible content keys will be loaded as eagerly as possible, potentially handled by the delegate. Setting to YES may result in network activity.

Any work done as a result of setting this property will be performed asynchronously.

Source

pub unsafe fn setPreloadsEligibleContentKeys( &self, preloads_eligible_content_keys: bool, )

Setter for preloadsEligibleContentKeys.

Source §

impl AVAssetResourceLoader

AVAssetResourceLoaderCommonMediaClientDataSupport.

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pub unsafe fn sendsCommonMediaClientDataAsHTTPHeaders(&self) -> bool

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pub unsafe fn setSendsCommonMediaClientDataAsHTTPHeaders( &self, sends_common_media_client_data_as_http_headers: bool, )

Setter for sendsCommonMediaClientDataAsHTTPHeaders.

Methods from Deref<Target = NSObject>§

Source

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`
    }
}