iOS10, camera permission - black screen for "camera app" - ios

Question

Of course with iOS 10, you now have to do THIS
to use the phone's camera. On first launch, the user gets a question such as,
and all is well.
BUT we have a client app that is a "camera app": when you launch the app it simply immediately launches the camera, when the app is running the camera is running and is shown fullscreen. The code to do so is the usual way, see below.
The problem is - the first launch of the app on a phone, the user is asked the question; user says yes. But then, the camera is just black on devices we have tried. It does not crash (as it would if you forget the plist item) but it goes black and stays black.
If the user quits the app and launches it again - it's fine, everything works.
What the heck is the workflow for a "camera app"? I can't see a good solution, but there must be one for the various camera apps out there - which immediately go to fullscreen camera when you launch the app.
class CameraPlane:UIViewController
{
...
func cameraBegin()
{
captureSession = AVCaptureSession()
captureSession!.sessionPreset = AVCaptureSessionPresetPhoto
let backCamera = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
var error: NSError?
var input: AVCaptureDeviceInput!
do {
input = try AVCaptureDeviceInput(device: backCamera)
} catch let error1 as NSError
{
error = error1
input = nil
}
if ( error != nil )
{
print("probably on simulator? no camera?")
return;
}
if ( captureSession!.canAddInput(input) == false )
{
print("capture session problem?")
return;
}
captureSession!.addInput(input)
stillImageOutput = AVCaptureStillImageOutput()
stillImageOutput!.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]
if ( captureSession!.canAddOutput(stillImageOutput) == false )
{
print("capture session with stillImageOutput problem?")
return;
}
captureSession!.addOutput(stillImageOutput)
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer!.videoGravity = AVLayerVideoGravityResizeAspectFill
// or, AVLayerVideoGravityResizeAspect
fixConnectionOrientation()
view.layer.addSublayer(previewLayer!)
captureSession!.startRunning()
previewLayer!.frame = view.bounds
}

Answer 1

Note: it's likely OP's code was actually working correctly in terms of the new ISO10 permission string, and OP had another problem causing the black screen.
From the code you've posted, I can't tell why you experience this kind of behavior. I can only give you the code that is working for me.
This code also runs on iOS 9. Note that I am loading the camera in viewDidAppear to make sure that all constraints are set.
import AVFoundation
class ViewController : UIViewController {
//the view where the camera feed is shown
#IBOutlet weak var cameraView: UIView!
var captureSession: AVCaptureSession = {
let session = AVCaptureSession()
session.sessionPreset = AVCaptureSessionPresetPhoto
return session
}()
var sessionOutput = AVCaptureStillImageOutput()
var previewLayer = AVCaptureVideoPreviewLayer()
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let devices = AVCaptureDevice.devices(withMediaType: AVMediaTypeVideo) as? [AVCaptureDevice]
guard let backCamera = (devices?.first { $0.position == .back }) else {
print("The back camera is currently not available")
return
}
do {
let input = try AVCaptureDeviceInput(device: backCamera)
if captureSession.canAddInput(input){
captureSession.addInput(input)
sessionOutput.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]
if captureSession.canAddOutput(sessionOutput) {
captureSession.addOutput(sessionOutput)
captureSession.startRunning()
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
previewLayer.connection.videoOrientation = .portrait
cameraView.layer.addSublayer(previewLayer)
previewLayer.position = CGPoint(x: cameraView.frame.width / 2, y: cameraView.frame.height / 2)
previewLayer.bounds = cameraView.frame
}
}
} catch {
print("Could not create a AVCaptureSession")
}
}
}
If you want the camera to show fullscreen you can simply use view instead of cameraView. In my camera implementation the camera feed does not cover the entire view, there's still some navigation stuff.

Answer 2

What's happening is that on that first launch, you're activating the camera before it can check what the permissions are and display the appropriate UIAlertController. What you'd want to do is include this code inside an if statement to check the status of the camera permissions (AVAuthorizationStatus). Make sure that if it's not allowed to ask for permission before displaying the camera. See this question for more help.