Struct AVCaptureDeviceDiscoverySession

#[repr(C)]
pub struct AVCaptureDeviceDiscoverySession { /* private fields */ }

Available on crate feature AVCaptureDevice only.

The AVCaptureDeviceDiscoverySession allows clients to search for devices by certain criteria.

This class allows clients to discover devices by providing certain search criteria. The objective of this class is to help find devices by device type and optionally by media type or position and allow you to key-value observe changes to the returned devices list.

See also Apple’s documentation

Implementations

impl AVCaptureDeviceDiscoverySession

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

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

pub unsafe fn discoverySessionWithDeviceTypes_mediaType_position( device_types: &NSArray<AVCaptureDeviceType>, media_type: Option<&AVMediaType>, position: AVCaptureDevicePosition, ) -> Retained<Self>

Available on crate feature AVMediaFormat only.

Returns an AVCaptureDeviceDiscoverySession instance for the given device types, media type, and position.

Parameter deviceTypes: An array specifying the device types to include in the list of discovered devices.

Parameter mediaType: The media type, such as AVMediaTypeVideo, AVMediaTypeAudio, or AVMediaTypeMuxed, to include in the list of discovered devices. Pass nil to search for devices with any media type.

Parameter position: The position to include in the list of discovered devices. Pass AVCaptureDevicePositionUnspecified to search for devices with any position.

Returns: The AVCaptureDeviceDiscoverySession from which the list of devices can be obtained.

The list of device types is mandatory. This is used to make sure that clients only get access to devices of types they expect. This prevents new device types from automatically being included in the list of devices.

pub unsafe fn devices(&self) -> Retained<NSArray<AVCaptureDevice>>

The list of devices that comply to the search criteria specified on the discovery session.

The returned array contains only devices that are available at the time the method is called. Applications can key-value observe this property to be notified when the list of available devices has changed. For apps linked against iOS 10, the devices returned are unsorted. For apps linked against iOS 11 or later, the devices are sorted by AVCaptureDeviceType, matching the order specified in the deviceTypes parameter of +[AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:mediaType:position:]. If a position of AVCaptureDevicePositionUnspecified is specified, the results are further ordered by position in the AVCaptureDevicePosition enum. Starting in Mac Catalyst 14.0, clients can key value observe the value of this property to be notified when the devices change.

pub unsafe fn supportedMultiCamDeviceSets( &self, ) -> Retained<NSArray<NSSet<AVCaptureDevice>>>

An array of sets of AVCaptureDevices that are allowed to be used simultaneously in an AVCaptureMultiCamSession.

When using an AVCaptureMultiCamSession, multiple cameras may be used as device inputs to the session, so long as they are included in one of the supportedMultiCamDeviceSets. Starting in Mac Catalyst 14.0, clients can key value observe the value of this property to be notified when the device sets change.

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

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());

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.

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`
    }
}

Trait Implementations

impl AsRef<AVCaptureDeviceDiscoverySession> for AVCaptureDeviceDiscoverySession

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AnyObject> for AVCaptureDeviceDiscoverySession

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for AVCaptureDeviceDiscoverySession

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AnyObject> for AVCaptureDeviceDiscoverySession

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for AVCaptureDeviceDiscoverySession

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for AVCaptureDeviceDiscoverySession

const NAME: &'static str = "AVCaptureDeviceDiscoverySession"

The name of the Objective-C class that this type represents.

type Super = NSObject

The superclass of this class.

type ThreadKind = <<AVCaptureDeviceDiscoverySession as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl Debug for AVCaptureDeviceDiscoverySession

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for AVCaptureDeviceDiscoverySession

type Target = NSObject

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for AVCaptureDeviceDiscoverySession

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for AVCaptureDeviceDiscoverySession

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for AVCaptureDeviceDiscoverySession

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl PartialEq for AVCaptureDeviceDiscoverySession

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for AVCaptureDeviceDiscoverySession

const ENCODING_REF: Encoding = <NSObject as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for AVCaptureDeviceDiscoverySession

impl Eq for AVCaptureDeviceDiscoverySession