Get Camera Preview to AVCaptureVideoPreviewLayer - ios

Question

I was trying to get the camera input to show on a preview layer view.
self.cameraPreviewView is tied to a UIView in IB
Here is my current code that I put together from the AV Foundation Programming Guide. But the preview never shows
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetHigh;
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
NSLog(#"Couldn't create video capture device");
}
[session addInput:input];
// Create video preview layer and add it to the UI
AVCaptureVideoPreviewLayer *newCaptureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
UIView *view = self.cameraPreviewView;
CALayer *viewLayer = [view layer];
newCaptureVideoPreviewLayer.frame = view.bounds;
[viewLayer addSublayer:newCaptureVideoPreviewLayer];
self.cameraPreviewLayer = newCaptureVideoPreviewLayer;
[session startRunning];

Answer 1

So after some trial and error and looking at apple's AVCam Sample Code
I wrapped the PreviewLayer code and session startRunning into a grand central dispatch block like so and it started working.
dispatch_async(dispatch_get_main_queue(), ^{
AVCaptureVideoPreviewLayer *newCaptureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
UIView *view = self.cameraPreviewView;
CALayer *viewLayer = [view layer];
newCaptureVideoPreviewLayer.frame = view.bounds;
[viewLayer addSublayer:newCaptureVideoPreviewLayer];
self.cameraPreviewLayer = newCaptureVideoPreviewLayer;
[session startRunning];
});

Answer 2

here is my code, it works perfect for me , you can refer to it
- (void)initCapture
{
AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:nil];
if (!captureInput) {
return;
}
AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];
/* captureOutput:didOutputSampleBuffer:fromConnection delegate method !*/
[captureOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
[captureOutput setVideoSettings:videoSettings];
self.captureSession = [[AVCaptureSession alloc] init];
NSString* preset = 0;
if (!preset) {
preset = AVCaptureSessionPresetMedium;
}
self.captureSession.sessionPreset = preset;
if ([self.captureSession canAddInput:captureInput]) {
[self.captureSession addInput:captureInput];
}
if ([self.captureSession canAddOutput:captureOutput]) {
[self.captureSession addOutput:captureOutput];
}
//handle prevLayer
if (!self.captureVideoPreviewLayer) {
self.captureVideoPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
}
//if you want to adjust the previewlayer frame, here!
self.captureVideoPreviewLayer.frame = self.view.bounds;
self.captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer: self.captureVideoPreviewLayer];
[self.captureSession startRunning];
}