我試圖切換此代碼，以使用前置攝像頭

Question

我是新手編程，並試圖修復此代碼使用前置攝像頭，而不是默認背面。我不知道我需要改變以使其正常工作。

這裏是我的示例代碼：

-(void)viewWillAppear:(BOOL)animated{ 
session = [[AVCaptureSession alloc] init]; 
[session setSessionPreset:AVCaptureSessionPresetPhoto]; 

AVCaptureDevice *inputDevice = [AVCaptureDevice  defaultDeviceWithMediaType:AVMediaTypeVideo]; 
NSError *error; 
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error]; 

if ([session canAddInput:deviceInput]) { 
    [session addInput:deviceInput]; 
} 

AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session]; 
       [previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill]; 
              CALayer *rootLayer = [[self view] layer]; 
              [rootLayer setMasksToBounds:YES]; 
              CGRect frame = self.frameForCapture.frame; 

[previewLayer setFrame:frame]; 

[rootLayer insertSublayer:previewLayer atIndex:0]; 


stillImageOutput = [[AVCaptureStillImageOutput alloc] init]; 
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil]; 
[stillImageOutput setOutputSettings:outputSettings]; 

[session addOutput:stillImageOutput]; 

[session startRunning]; 

Answer 1

替換此：

AVCaptureDevice *inputDevice = [AVCaptureDevice  defaultDeviceWithMediaType:AVMediaTypeVideo]; 
NSError *error; 
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error]; 

有了這個：

NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; 
AVCaptureDevice *frontCamera; 
for (AVCaptureDevice *dev in devices) { 
    if (dev.position == AVCaptureDevicePositionFront) { 
     frontCamera = dev; 
     break; 
    } 
} 
if (!frontCamera) { 
    NSLog(@"No front camera found!"); 
    // Handle no front camera error 
} 
NSError *error; 
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:frontCamera error:&error];