iOS custom camera (take photo), appear a bug - ios

Question

this bug appears very accidental, I have no idea how to fix, please help me,
main code is here:
if you want to see the complete project, you can check this link
https://github.com/liman123/custom-camera
the bug is : when I take photo, the screen become this pic, this pic is distorted!
- (void)setupConfiguration
{
_captureSession = [[AVCaptureSession alloc]init];
_captureSession.sessionPreset = AVCaptureSessionPresetPhoto;
_capturedImageView = [[UIImageView alloc]init];
_capturedImageView.frame = self.view.frame; // just to even it out
_capturedImageView.backgroundColor = [UIColor clearColor];
_capturedImageView.userInteractionEnabled = YES;
_capturedImageView.contentMode = UIViewContentModeScaleAspectFill;
_captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:_captureSession];
_captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
_captureVideoPreviewLayer.frame = self.view.bounds;
[self.view.layer addSublayer:_captureVideoPreviewLayer];
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
if (devices.count > 0) {
_captureDevice = devices[0];
NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:_captureDevice error:&error];
[_captureSession addInput:input];
_stillImageOutput = [[AVCaptureStillImageOutput alloc]init];
NSDictionary * outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
[_stillImageOutput setOutputSettings:outputSettings];
[_captureSession addOutput:_stillImageOutput];
}
}
-(void)captureButtonClick
{
_isCapturingImage = YES;
AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in _stillImageOutput.connections)
{
for (AVCaptureInputPort *port in [connection inputPorts])
{
if ([[port mediaType] isEqual:AVMediaTypeVideo] )
{
videoConnection = connection;
break;
}
}
if (videoConnection) {
break;
}
}
[_stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) {
if (imageSampleBuffer) {
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
UIImage *capturedImage = [[UIImage alloc]initWithData:imageData scale:1];
_isCapturingImage = NO;
_capturedImageView.image = capturedImage;
_selectedImage = capturedImage;
imageData = nil;
[self.view addSubview:_imageSelectedView];
}
}];
}