Class: AVCaptureMetadataOutput
- Inherits:
-
AVCaptureOutput
- Object
- NSObject
- AVCaptureOutput
- AVCaptureMetadataOutput
Overview
An AVCaptureMetadataOutput object intercepts metadata objects emitted by its associated capture connection and forwards them to a delegate object for processing. You can use instances of this class to process specific types of metadata included with the input data. You use this class like you do other output objects, typically by adding it as an output to an AVCaptureSession object.
Instance Attribute Summary (collapse)
-
- availableMetadataObjectTypes
readonly
An array of strings identifying the types of metadata objects that can be captured.
-
- metadataObjectsCallbackQueue
readonly
The dispatch queue on which to execute the delegate’s methods.
-
- metadataObjectsDelegate
readonly
The delegate of the receiver.
-
- metadataObjectTypes
An array of strings identifying the types of metadata objects that you want to process.
Attributes inherited from AVCaptureOutput
Instance Method Summary (collapse)
-
- setMetadataObjectsDelegate:queue:
Sets the delegate and dispatch queue to use handle callbacks.
Methods inherited from AVCaptureOutput
#connectionWithMediaType:, #transformedMetadataObjectForMetadataObject:connection:
Methods inherited from NSObject
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Constructor Details
This class inherits a constructor from NSObject
Dynamic Method Handling
This class handles dynamic methods through the method_missing method in the class NSObject
Instance Attribute Details
- (Array) availableMetadataObjectTypes (readonly)
An array of strings identifying the types of metadata objects that can be captured. (read-only) Each string in the array corresponds to a possible value in the type property of the AVMetadataObject objects reported by the receiver. The available types are dependent on the capabilities of the AVCaptureInputPort to which the receiver’s connection is attached.
- (dispatch_queue_t) metadataObjectsCallbackQueue (readonly)
The dispatch queue on which to execute the delegate’s methods. (read-only) To set the dispatch queue, you must use the setMetadataObjectsDelegate:queue: method.
- (Object) metadataObjectsDelegate (readonly)
The delegate of the receiver. (read-only) The delegate object must conform to the AVCaptureMetadataOutputObjectsDelegate protocol. The object in this property is used to process all metadata objects captured from the receiver’s connection. To set the delegate object, you must use the setMetadataObjectsDelegate:queue: method.
- (Array) metadataObjectTypes
An array of strings identifying the types of metadata objects that you want to process. Each string in the array corresponds to a possible value in the type property of the AVMetadataObject objects reported by the receiver. You can use this property to filter the metadata objects reported by the receiver. Only metadata objects whose type matches one of the strings in this property are actually forwarded to the delegate for processing. Assigning an empty array to this property removes any filters and allows all objects to be processed.When assigning a new array to this property, the type strings in the array must match the type strings reported by the availableMetadataObjectTypes property. If you specify a type string that is not in the availableMetadataObjectTypes array, the receiver raises an exception.
Instance Method Details
- (Object) setMetadataObjectsDelegate(objectsDelegate, queue:objectsCallbackQueue)
Sets the delegate and dispatch queue to use handle callbacks. When new metadata objects are captured from the receiver’s connection, they are vended to the delegate object. All delegate methods are executed on the dispatch queue specified in the objectsCallbackQueue parameter. To ensure that metadata objects are processed in a timely manner and not dropped, you should specify a dispatch queue dedicated to processing the objects or that is otherwise not busy.