小编use*_*934的帖子

我正在使用以下方法设置自iOS 4以来的焦点:

- (void) focusAtPoint:(CGPoint)point
{
    AVCaptureDevice *device = [[self captureInput] device];

    NSError *error;

     if ([device isFocusModeSupported:AVCaptureFocusModeAutoFocus] &&
         [device isFocusPointOfInterestSupported])
     {
         if ([device lockForConfiguration:&error]) {
             [device setFocusPointOfInterest:point];
             [device setFocusMode:AVCaptureFocusModeAutoFocus];
             [device unlockForConfiguration];
         } else {
             NSLog(@"Error: %@", error);
         }
     }
}

在iOS 4设备上,这没有任何问题.但是在iOS 5上,实时摄像头会冻结并在几秒钟后完全变黑.没有异常或错误抛出.

如果我注释掉setFocusPointOfInterest或setFocusMode,则不会发生错误.因此,它们的组合都会导致这种行为.