No error printed however function doesn't run - ios

Question

I am attempting to make a camera view appear, as you can see in my code below I have it set up to display any errors and not break the program if any errors occur, however when I do run this code no error occurs or camera view is displayed. I am running it on an actual phone and the phone did request if it had permission to use the camera. Below is the code
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
captureSession = AVCaptureSession()
captureSession?.sessionPreset = AVCaptureSessionPreset1920x1080
let backCamera = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
var input : AVCaptureDeviceInput?
let error : NSError?
do {
input = try AVCaptureDeviceInput(device: backCamera)
} catch let error as NSError? {
print(error)
if error == nil && (captureSession?.canAddInput(input))!{
captureSession?.addInput(input)
videoOutput = AVCaptureVideoDataOutput()
//videoOutput?.outputSettings = [AVVideoCodecKey : AVVideoCodecKey]
if ((captureSession?.canAddOutput(videoOutput)) != nil){
captureSession?.addOutput(videoOutput)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer?.videoGravity = AVLayerVideoGravityResizeAspect
previewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.Portrait
cameraView.layer.addSublayer(previewLayer!)
captureSession?.startRunning()
}
}
}
}

Answer 1

The body of catch is executed only if an error has occurred. so since your code is inside the catch block, it won't execute as it doesn't find any error.
So remove the code from the catch block and put it outside as suggested by #penatheboss.

Answer 2

Don't put code in the catch. That is if something goes wrong.
do {
input = try AVCaptureDeviceInput(device: backCamera)
} catch let error as NSError? {
print(error)
return//Stop rest of code
}
if (captureSession?.canAddInput(input))!{
captureSession?.addInput(input)
videoOutput = AVCaptureVideoDataOutput()
//videoOutput?.outputSettings = [AVVideoCodecKey : AVVideoCodecKey]
if ((captureSession?.canAddOutput(videoOutput)) != nil){
captureSession?.addOutput(videoOutput)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer?.videoGravity = AVLayerVideoGravityResizeAspect
previewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.Portrait
cameraView.layer.addSublayer(previewLayer!)
captureSession?.startRunning()
}
}