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iosavcapturedevice

What is the difference between AVCaptureDevice’s hasFlash and hasTorch properties?

AVCaptureDevice has both hasFlash and hasTorch properties (and similar other methods/properties). What is the difference between the flash and the torch?

Also, do any iOS devices exist with only one of the above?

Solution

  • On iPhone devices both cameras have flash: back camera has a LED camera flash and can operate in a torch mode and front camera uses display as a flash (displaying for the short period of time white screen emits enough light) but display cannot be used as a torch.

    Checking [device hasFlash] to set LED flash ON/OFF programmatically from the list of AVCaptureDevice:

    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];

    is not enough, since both cameras will pass condition [device hasFlash], but setting [device setTorchMode:AVCaptureTorchModeOn] for the front camera may cause app crash. The best is probably to check both:

    if ([device hasFlash] && [device hasTorch]) {
 [device lockForConfiguration:nil];
 [device setTorchMode:AVCaptureTorchModeOn]; // for example
 [device unlockForConfiguration];
}