iOS相机应用程序，从前置摄像头切换到后置摄像头时闪烁

Question

我正在尝试模仿相机应用程序从前置摄像头到后置摄像头的转换。它使用 UIViewAnimationOptionTransitionFlipFromLeft ..

我目前的方法是用前置摄像头拍照，切换到后置摄像头，用后置摄像头拍照，将它们加载到两个 UIImageViews 并使用 ImageView 执行转换..(隐藏当前相机流过程中)..

问题是当我调用从前置摄像头切换到后置摄像头时，cameraView(一个 AVCapturePreviewLayer)会在我隐藏它之前立即切换 View (这发生在最后一行的 flipCameraToFront 中.. [_captureSession commitConfiguration]) ...

希望这是有道理的，这里是我省略的一些代码，如果您认为这对我有帮助，请告诉我，我会发布其余部分。
任何帮助将不胜感激，谢谢

//class:RecordViewController
//iVars for this class..   
RecordVideoHandler *_recordHandler;
UIImage *_firstImageForFlip;
UIImage *_secondImageForFlip;
UIImageView *_firstImageViewForFlip;
BOOL isUsingFrontInput;
AVCaptureVideoPreviewLayer *_capturePreviewLayer;
UIView *_capturePreviewView;

- (void)doCameraFlip:(UIButton *)sender
{
    [_recordHandler addStillImageOutput];
    //This method calls imageReturned:(UIImage *)inImage;
    [_recordHandler captureAndReturnStillImage];


}   
- (void)imageReturned:(UIImage *)inImage{

    if(_firstImageForFlip == nil){
        [_capturePreviewLayer setFrame:CGRectZero];
        _firstImageForFlip = inImage;
        _firstImageViewForFlip = [[UIImageView alloc] initWithImage:_firstImageForFlip];


        if(isUsingFrontInput)
            [_firstImageViewForFlip setTransform:CGAffineTransformMakeScale(-1.0, 1.0)];


        [_firstImageViewForFlip setFrame:_capturePreviewView.bounds];
        [_capturePreviewView addSubview:_firstImageViewForFlip];


        if(isUsingFrontInput){
            [_recordHandler flipCameraToBack];
        }else{
            [_recordHandler flipCameraToFront];
        }
        [_recordHandler captureAndReturnStillImage];
    }else{
        _secondImageForFlip = inImage;
        [_recordHandler removeStillImageOutput];
        [self finishCameraFlip];
    }
}
- (void)finishCameraFlip{
    UIImageView *secondImageView = [[UIImageView alloc] initWithImage:_secondImageForFlip];
    [secondImageView setFrame:_capturePreviewView.bounds];

    if(!isUsingFrontInput)
        [secondImageView setTransform:CGAffineTransformMakeScale(-1.0, 1.0)];

    [UIView transitionWithView:_capturePreviewView duration:3.3f
options:UIViewAnimationOptionTransitionFlipFromLeft animations:
     ^{
         [_firstImageViewForFlip removeFromSuperview];
         [_capturePreviewLayer setFrame:_capturePreviewView.bounds];
         [_capturePreviewView addSubview:secondImageView];

     } completion:
     ^(BOOL finished){
         [secondImageView removeFromSuperview];
     }];

    isUsingFrontInput = isUsingFrontInput ? NO : YES;

    _firstImageForFlip = nil;
    _secondImageForFlip = nil;
    }

类:RecordVideoHandler

    //iVars for this class..    
    AVCaptureSession *_captureSession;

    - (void)flipCameraToFront
    {
    [_captureSession beginConfiguration];
    for (AVCaptureInput *input in _captureSession.inputs) {
        if (input == _captureRearInput) {
            [_captureSession removeInput:_captureRearInput];
            [_captureSession addInput:_captureFrontInput];
        }
    }
    _currentCaptureDevice = _captureDeviceFrontFacing;
    [_captureSession commitConfiguration];
}

Answer 1

如果有人想知道，我想通了。我不得不使用 performSelectors 来等待下一个运行循环，因为相机立即翻转，而 View 内容在运行循环之后等待等等……不确定具体细节，这是代码。

- (void)doCameraFlip:(UIButton *)sender
{
    NSLog(@"doCameraFlip");
    [_recordHandler addStillImageOutput];    
    [_recordHandler captureAndReturnStillImage];    
}
- (void)imageReturned:(UIImage *)inImage{
    [_recordHandler removeStillImageOutput];            
    _imageViewForFlip= [[UIImageView alloc] initWithImage:inImage];
    [_imageViewForFlip setFrame:_containerView.bounds];
    [_containerView addSubview:_imageViewForFlip];


    [self performSelector:@selector(cfe) withObject:nil afterDelay:0.0f];
    [self performSelector:@selector(cfe2) withObject:nil afterDelay:0.0f];

}
- (void)cfe{
    if(isUsingFrontInput){
        [_recordHandler flipCameraToBack];
    }else{
        [_recordHandler flipCameraToFront];
    }

}
- (void)cfe2{
    [UIView transitionWithView:_containerView duration:3.0f options:UIViewAnimationOptionTransitionFlipFromRight animations:^{
        [_imageViewForFlip removeFromSuperview]; 
        [_containerView addSubview:_capturePreviewView]; 
    } completion:nil];
}