Struct AVAudioSessionDataSourceDescription

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pub struct AVAudioSessionDataSourceDescription { /* private fields */ }

Available on crate feature AVAudioSessionRoute only.

Expand description

Information about one of potentially multiple data sources associated with a port.

Implementations§

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impl AVAudioSessionDataSourceDescription

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pub unsafe fn dataSourceID(&self) -> Retained<NSNumber>

System-assigned ID for the data source.

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

Human-readable name for the data source.

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pub unsafe fn location(&self) -> Option<Retained<AVAudioSessionLocation>>

Describes the general location of a data source. Will be nil for data sources for which the location is not known.

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pub unsafe fn orientation(&self) -> Option<Retained<AVAudioSessionOrientation>>

Describes the orientation of a data source. Will be nil for data sources for which the orientation is not known.

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pub unsafe fn supportedPolarPatterns( &self, ) -> Option<Retained<NSArray<AVAudioSessionPolarPattern>>>

Array of one or more AVAudioSessionPolarPatterns describing the supported polar patterns for a data source. Will be nil for data sources that have no selectable patterns.

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pub unsafe fn selectedPolarPattern( &self, ) -> Option<Retained<AVAudioSessionPolarPattern>>

Describes the currently selected polar pattern. Will be nil for data sources that have no selectable patterns.

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pub unsafe fn preferredPolarPattern( &self, ) -> Option<Retained<AVAudioSessionPolarPattern>>

Describes the preferred polar pattern. Will be nil for data sources that have no selectable patterns or if no preference has been set.

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pub unsafe fn setPreferredPolarPattern_error( &self, pattern: Option<&AVAudioSessionPolarPattern>, ) -> Result<(), Retained<NSError>>

Select the desired polar pattern from the set of available patterns. Setting a nil value will clear the preference.

Note: If the owning port and data source are part of the active audio route, changing the polar pattern will likely result in a route reconfiguration. If the owning port and data source are not part of the active route, selecting a polar pattern will not result in an immediate route reconfiguration. Use AVAudioSession’s setPreferredInput:error: method to activate the port. Use setPreferredDataSource:error: to active the data source on the port. You must call setPreferredInputOrientation:error: on the AVAudioSession if you chose the AVAudioSessionPolarPatternStereo polar pattern.

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impl AVAudioSessionDataSourceDescription

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() -> 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());

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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`
    }
}