AVFoundation將Swift代碼更改爲Objective-C

我找到了一個在Swift中編寫的AVFoundation示例代碼。我試圖將代碼更改爲Objective-C。但我不確定是否正確執行此操作，因爲此時代碼不起作用。你可以看看嗎？AVFoundation將Swift代碼更改爲Objective-C

func initialiseCaptureSession() 
{ 
    captureSession.sessionPreset = AVCaptureSessionPresetPhoto 

    guard let frontCamera = (AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo) as! [AVCaptureDevice]) 
     .filter({ $0.position == .Front }) 
     .first else 
    { 
     fatalError("Unable to access front camera") 
    } 

    do 
    { 
     let input = try AVCaptureDeviceInput(device: frontCamera) 

     captureSession.addInput(input) 
    } 
    catch 
    { 
     fatalError("Unable to access front camera") 
    } 

    let videoOutput = AVCaptureVideoDataOutput() 

    videoOutput.setSampleBufferDelegate(self, queue: dispatch_queue_create("sample buffer delegate", DISPATCH_QUEUE_SERIAL)) 
    if captureSession.canAddOutput(videoOutput) 
    { 
     captureSession.addOutput(videoOutput) 
    } 

    captureSession.startRunning() 
}

我的Objective-C代碼：

-(void)initializeCaptureSession { 

self.captureSession.sessionPreset = AVCaptureSessionPresetPhoto; 

AVCaptureDevice *inputDevice = nil; 

NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; 
AVCaptureDeviceInput *deviceInput; 

for(AVCaptureDevice *camera in devices) { 

    if([camera position] == AVCaptureDevicePositionFront) { // is front camera 
     inputDevice = camera; 
     deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:nil]; 
     [self.captureSession addInput:deviceInput]; 
     break; 
    } 
} 
AVCaptureVideoDataOutput *videoOutput = nil; 
[videoOutput setSampleBufferDelegate:self queue:dispatch_queue_create("sample buffer delegate", DISPATCH_QUEUE_SERIAL)]; 
if([self.captureSession canAddOutput:videoOutput]) { 
    [self.captureSession addOutput:videoOutput]; 
} 
[self.captureSession startRunning];

}

的問題是，在我的情況

if([self.captureSession canAddOutput:videoOutput]) { [self.captureSession addOutput:videoOutput]; }

被忽略。我不確定，但是我的self.captureSession addInput：deviceInput];？

最好的問候，納扎爾

來源

2016-05-26 Nazar Medeiros

有一個問題，此行

AVCaptureVideoDataOutput *videoOutput = nil;

的AVCaptureVideoDataOutput將不會被初始化，因此canAddOutput:videoOutput失敗。

你可以像這樣初始化它;

videoOutput = [[AVCaptureVideoDataOutput alloc] init];

來源

2016-05-26 17:22:07 Xcoder

感謝兄弟。這工作！我也試着用** AVCaptureDevice * inputDevice = [[AVCaptureDevice alloc] init]來初始化** AVCaptureDevice * inputDevice = nil; **; **但這造成了一個例外。我是否也必須初始化？ –

AVFoundation將Swift代碼更改爲Objective-C

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