Struct AVCaptureMetadataInput 

pub struct AVCaptureMetadataInput { /* private fields */ }

Available on crate feature AVCaptureInput only.

AVCaptureMetadataInput is a concrete subclass of AVCaptureInput that provides a way for clients to supply AVMetadataItems to an AVCaptureSession.

Instances of AVCaptureMetadataInput are input sources for AVCaptureSession that provide AVMetadataItems to an AVCaptureSession. AVCaptureMetadataInputs present one and only one AVCaptureInputPort, which currently may only be connected to an AVCaptureMovieFileOutput. The metadata supplied over the input port is provided by the client, and must conform to a client-supplied CMFormatDescription. The AVMetadataItems are supplied in an AVTimedMetadataGroup.

See also Apple’s documentation

Implementations

impl AVCaptureMetadataInput

pub unsafe fn metadataInputWithFormatDescription_clock( desc: &CMMetadataFormatDescription, clock: &CMClock, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Returns an AVCaptureMetadataInput instance that allows a client to provide AVTimedMetadataGroups to an AVCaptureSession.

Parameter desc: A CMFormatDescription that defines the metadata to be supplied by the client. Throws an NSInvalidArgumentException if NULL is passed.

Parameter clock: A CMClock that provided the timebase for the supplied samples. Throws an NSInvalidArgumentException if NULL is passed.

Returns: An AVCaptureMetadataInput instance.

This method returns an instance of AVCaptureMetadataInput that can be used to capture AVTimedMetadataGroups supplied by the client to an AVCaptureSession.

pub unsafe fn initWithFormatDescription_clock( this: Allocated<Self>, desc: &CMMetadataFormatDescription, clock: &CMClock, ) -> Retained<Self>

Available on crate feature objc2-core-media only.

Creates an AVCaptureMetadataInput instance that allows a client to provide AVTimedMetadataGroups to an AVCaptureSession.

Parameter desc: A CMFormatDescription that defines the metadata to be supplied by the client. Throws NSInvalidArgumentException if NULL is passed.

Parameter clock: A CMClock that provided the timebase for the supplied samples. Throws NSInvalidArgumentException if NULL is passed.

Returns: An AVCaptureMetadataInput instance, or nil, if the device could not be used for capture.

This method creates an instance of AVCaptureMetadataInput that can be used to capture AVTimedMetadataGroups supplied by the client to an AVCaptureSession.

pub unsafe fn appendTimedMetadataGroup_error( &self, metadata: &AVTimedMetadataGroup, ) -> Result<(), Retained<NSError>>

Available on crate feature AVTimedMetadataGroup only.

Provides metadata to the AVCaptureSession.

Parameter metadata: An AVTimedMetadataGroup of metadata. Will throw an exception if nil. In order to denote a period of no metadata, an empty AVTimedMetadataGroup should be passed.

The provided AVTimedMetadataGroup will be provided to the AVCaptureSession. The group’s presentation timestamp is expressed in the context of the clock supplied to the initializer. It is not required that the AVTimedMetadataGroup have a duration; an empty AVTimedMetadataGroup can be supplied to denote a period of no metadata.

impl AVCaptureMetadataInput

Methods declared on superclass AVCaptureInput.

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

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

Methods from Deref<Target = AVCaptureInput>

pub unsafe fn ports(&self) -> Retained<NSArray<AVCaptureInputPort>>

The ports owned by the receiver.

The value of this property is an array of AVCaptureInputPort objects, each exposing an interface to a single stream of media data provided by an input.

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.

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());

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<AVCaptureInput> for AVCaptureMetadataInput

fn as_ref(&self) -> &AVCaptureInput

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

impl AsRef<AVCaptureMetadataInput> for AVCaptureMetadataInput

fn as_ref(&self) -> &Self

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

impl AsRef<AnyObject> for AVCaptureMetadataInput

fn as_ref(&self) -> &AnyObject

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

impl AsRef<NSObject> for AVCaptureMetadataInput

fn as_ref(&self) -> &NSObject

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

impl Borrow<AVCaptureInput> for AVCaptureMetadataInput

fn borrow(&self) -> &AVCaptureInput

Immutably borrows from an owned value.

impl Borrow<AnyObject> for AVCaptureMetadataInput

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for AVCaptureMetadataInput

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for AVCaptureMetadataInput

const NAME: &'static str = "AVCaptureMetadataInput"

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

type Super = AVCaptureInput

The superclass of this class.

type ThreadKind = <<AVCaptureMetadataInput 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 AVCaptureMetadataInput

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

Formats the value using the given formatter.

impl Deref for AVCaptureMetadataInput

type Target = AVCaptureInput

The resulting type after dereferencing.

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

Dereferences the value.

impl Hash for AVCaptureMetadataInput

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 AVCaptureMetadataInput

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

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for AVCaptureMetadataInput

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 AVCaptureMetadataInput

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 AVCaptureMetadataInput

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

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

impl DowncastTarget for AVCaptureMetadataInput

impl Eq for AVCaptureMetadataInput