在应用程序使用iOS9图片模式时拍摄照片时出现iOS NSInternalInconsistencyException

我在尝试拍摄照片时遇到了崩溃(前置摄像头),只有在用户使用图片模式拍摄单独的应用视频时才会失败.如果用户没有图片中的视频,一切正常.崩溃发生在这一行：

[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer,NSError *error) {

有错误

*** TerminaTing app due to uncaught exception 'NSInternalInconsistencyException',reason: '*** -[AVCaptureStillImageOutput captureStillImageAsynchronouslyFromConnection:completionHandler:] - inconsistent state.'

我尝试检查手机是否在使用图片模式时无法拍摄照片,但默认的iOS相机应用程序可以拍摄照片(尽管它可能使用不同的拍照方法). stillImageOutput和videoConnection似乎设置得很好,并不是零.

以下是导致此崩溃的代码,以防它有所帮助.

avCaptureSession = [[AVCaptureSession alloc] init];
AVCaptureDevice* cameraDevice = [GS60_FriendFeed_ScreenshotSelfie_Preview_View frontFacingCameraIfAvailable];
avCaptureSession.sessionPreset = avCaptureSessionPresetString;

NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:cameraDevice error:&error];
if (!input) {
    NSLog(@"ERROR: trying to open camera: %@",error);
}
[avCaptureSession addInput:input];
AVCaptureStillImageOutput* stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSetTings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG,AVVideoCodecKey,nil];
[stillImageOutput setOutputSetTings:outputSetTings];
[avCaptureSession addOutput:stillImageOutput];
[avCaptureSession startRunning];

然后

AVCaptureConnection* videoConnection = nil;
AVCaptureStillImageOutput* stillImageOutput = [[avCaptureSession outputs] objectATindex:0];
for (AVCaptureConnection* connection in stillImageOutput.connections) {
    for (AVCaptureInputPort *port in [connection inputPorts]) {
        if ([[port mediaType] isEqual:AVMediaTypeVideo] ) {
            videoConnection = connection;
            break;
        }
    }
    if (videoConnection) { break; }
}

UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
AVCaptureVideoOrientation avcaptureOrientation = AVCaptureVideoOrientationPorTrait;
if(orientation == UIInterfaceOrientationUnkNown) {
    avcaptureOrientation = AVCaptureVideoOrientationPorTrait;
} else if(orientation == UIInterfaceOrientationPorTrait) {
    avcaptureOrientation = AVCaptureVideoOrientationPorTrait;
} else if(orientation == UIInterfaceOrientationPorTraitUpsideDown) {
    avcaptureOrientation = AVCaptureVideoOrientationPorTraitUpsideDown;
} else if(orientation == UIInterfaceOrientationLandscapeLeft) {
    avcaptureOrientation = AVCaptureVideoOrientationLandscapeLeft;
} else if(orientation == UIInterfaceOrientationLandscapeRight) {
    avcaptureOrientation = AVCaptureVideoOrientationLandscapeRight;
}
[videoConnection setVideoOrientation:avcaptureOrientation];

//this line flips the image so it uses exactly what the preview shows
[videoConnection setVideoMirrored:YES];
[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer,NSError *error) {
...

我希望能够拍摄照片,但是如果图片中的图片是开放的那样是不可能的,那么知道如何检测到我们将无法拍摄它仍然会有所帮助.

谢谢你的帮助.

if (!videoConnection || !videoConnection.enabled || !videoConnection.activE) {
    // Raise error here / warn user... 
    return;
}
UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
AVCaptureVideoOrientation avcaptureOrientation = AVCaptureVideoOrientationPorTrait;