Struct AVAssetVariantAudioRenditionSpecificAttributes

Source

pub struct AVAssetVariantAudioRenditionSpecificAttributes { /* private fields */ }

Available on crate feature AVAssetVariant only.

Expand description

Audio rendition attributes for an asset variant.

Subclasses of this type that are used from Swift must fulfill the requirements of a Sendable type.

Implementations§

Source §

impl AVAssetVariantAudioRenditionSpecificAttributes

Source

pub unsafe fn channelCount(&self) -> NSInteger

If it is not declared, the value will be negative.

A channel count greater than two indicates that the variant offers a rich multichannel authoring.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn isBinaural(&self) -> bool

Indicates that the variant is best suited for delivery to headphones.

A binaural variant may originate from a direct binaural recording or from the processing of a multichannel audio source.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn isImmersive(&self) -> bool

Indicates that this variant contains virtualized or otherwise pre-processed audio content that is suitable for a variety of purposes.

If a variant audio redition is immersive it is eligible for rendering either to headphones or speakers.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn isDownmix(&self) -> bool

Indicates that this variant is declared as a downmix derivative of other media of greater channel count.

If one or more multichannel variants are also provided, the dowmix is assumed to be compatible in its internal timing and other attributes with those variants. Typically this is because it has been derived from the same source. A downmix can be used as a suitable substitute for a multichannel variant under some conditions.

This property is not atomic.

§Safety

This might not be thread-safe.

Source §

impl AVAssetVariantAudioRenditionSpecificAttributes

Methods declared on superclass NSObject.

Source

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

Source

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

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>§

Source

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`
    }
}