Struct AVAudioChannelLayout

Source

pub struct AVAudioChannelLayout { /* private fields */ }

Available on crate feature AVAudioChannelLayout only.

Expand description

A description of the roles of a set of audio channels.

This object is a thin wrapper for the AudioChannelLayout structure, described in <CoreAudio /CoreAudioTypes.h>.

Implementations§

Source §

impl AVAudioChannelLayout

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

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pub unsafe fn initWithLayoutTag( this: Allocated<Self>, layout_tag: AudioChannelLayoutTag, ) -> Option<Retained<Self>>

Available on crate feature objc2-core-audio-types only.

Initialize from a layout tag.

Parameter layoutTag: The tag.

Returns nil if the tag is either kAudioChannelLayoutTag_UseChannelDescriptions or kAudioChannelLayoutTag_UseChannelBitmap.

Source

pub unsafe fn initWithLayout( this: Allocated<Self>, layout: NonNull<AudioChannelLayout>, ) -> Retained<Self>

Available on crate feature objc2-core-audio-types only.

Initialize from an AudioChannelLayout.

Parameter layout: The AudioChannelLayout.

If the provided layout’s tag is kAudioChannelLayoutTag_UseChannelDescriptions, this initializer attempts to convert it to a more specific tag.

§Safety

layout must be a valid pointer.

Source

pub unsafe fn isEqual(&self, object: &AnyObject) -> bool

Determine whether another AVAudioChannelLayout is exactly equal to this layout.

Parameter object: The AVAudioChannelLayout to compare against.

The underlying AudioChannelLayoutTag and AudioChannelLayout are compared for equality.

§Safety

object should be of the correct type.

Source

pub unsafe fn layoutWithLayoutTag( layout_tag: AudioChannelLayoutTag, ) -> Retained<Self>

Available on crate feature objc2-core-audio-types only.

Create from a layout tag.

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pub unsafe fn layoutWithLayout( layout: NonNull<AudioChannelLayout>, ) -> Retained<Self>

Available on crate feature objc2-core-audio-types only.

Create from an AudioChannelLayout

§Safety

layout must be a valid pointer.

Source

pub unsafe fn layoutTag(&self) -> AudioChannelLayoutTag

Available on crate feature objc2-core-audio-types only.

The layout’s tag.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn layout(&self) -> NonNull<AudioChannelLayout>

Available on crate feature objc2-core-audio-types only.

The underlying AudioChannelLayout.

This property is not atomic.

§Safety

This might not be thread-safe.

Source

pub unsafe fn channelCount(&self) -> AVAudioChannelCount

Available on crate feature AVAudioTypes only.

The number of channels of audio data.

This property is not atomic.

§Safety

This might not be thread-safe.

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impl AVAudioChannelLayout

Methods declared on superclass NSObject.

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pub unsafe fn new() -> 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.

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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`
    }
}