Instance Method


Sets the bias to be applied to the target exposure value.


- (void)setExposureTargetBias:(float)bias completionHandler:(void (^)(CMTime syncTime))handler;



The bias to be applied to the exposure target value.


A block to be called when the exposureTargetBias property has been set to the value specified.

The block receives a timestamp that matches that of the first buffer to which the setting has been applied. The timestamp is synchronized to the device clock, and thus must be converted to the master clock before comparison with the timestamps of buffers delivered via an AVCaptureVideoDataOutput instance.

The client may pass nil for the handler parameter if knowledge of the operation's completion is not required.


This method is the only way to set the exposureTargetBias property.

This method throws an NSInvalidArgumentException exception if exposureTargetBias is set to an unsupported level. A NSGenericException exception is thrown if this method is invoked without first obtaining exclusive access to the receiver using lockForConfiguration:.

See Also

Managing Image Exposure


The length of time over which exposure takes place.

- setExposureModeCustomWithDuration:ISO:completionHandler:

Locks the exposure duration and ISO at the specified values.


The metered exposure level's offset from the target exposure value, in EV units.


Bias applied to the target exposure value, in EV units.


The minimum supported exposure bias, in EV units.


The maximum supported exposure bias, in EV units.


The maximum exposure duration, in seconds, defined in the auto-exposure algorithm.


A special constant representing the current exposure bias value.


A special constant representing the current exposure duration setting.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software