AVFoundation - How to control exposure

Question

AFTER tapping to take picture, I want to lock exposure and turn off torch as soon as exposure is no longer adjusting. So, I added an observer to handle adj

Answer 1

It is almost certainly a timing issue. Call captureStillImageAsynchronouslyFromConnection:completionHandler: inside your if block. Then the capture will always be executed after exposure has been locked.

if ([self.inputDevice isExposureModeSupported:AVCaptureExposureModeLocked]) {
    dispatch_async(dispatch_get_main_queue(), 
        ^{
            NSError *error = nil;
            if ([self.inputDevice lockForConfiguration:&error]) {
                //code to lock exposure here
                //take photo here
            }
        });
}