How to capture a still image with AVFoundation and display the image in another view controller using Swift

Question

GOAL: I am using AVFoundation to a create custom camera that acts similar to Facebook, Instagram, and Snapchats camera image capturing sequence.

Below is my controller with the ideal UX:

User presses plus sign button
app segues/transitions to custom camera View Controller using AVCaptureSession and AVCaptureVideoPreviewLayer, shown as purple area
User presses Take button to capture image
app segues to a still/image View controller of the picture they just took so the user can edit or whatever else must happen
user presses Use button
app saves the image and pops to the root ViewController

Here is my Swift Storyboard of the above

PROBLEM: I am able to get a live video feed to using AVCapturePreviewLayer however once I capture my picture I am unable to transfer the captured UIImage to the second ViewController. I am using a segue that I trigger at the end captureStillImageAsynchronouslyFromConnection completion callback.

Here is the MasterViewController?

class AddPhotoViewController: UIViewController {


@IBOutlet var previewLayerView: UIView!


var captureSession: AVCaptureSession?
var previewLayer: AVCaptureVideoPreviewLayer?
var stillImageOutput: AVCaptureStillImageOutput?
var imageDetail: UIImage?


@IBAction func cancelCameraBtn(sender: AnyObject) {

    self.navigationController?.popToRootViewControllerAnimated(true)

}



@IBAction func takePhotoBtn(sender: AnyObject) {


    if let videoConnection = stillImageOutput!.connectionWithMediaType(AVMediaTypeVideo) {


        videoConnection.videoOrientation = AVCaptureVideoOrientation.Portrait

        stillImageOutput?.captureStillImageAsynchronouslyFromConnection(videoConnection, completionHandler: {(sampleBuffer, error) in

            if (sampleBuffer != nil) {
                let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(sampleBuffer)
                let dataProvider = CGDataProviderCreateWithCFData(imageData)
                let cgImageRef = CGImageCreateWithJPEGDataProvider(dataProvider, nil, true, CGColorRenderingIntent.RenderingIntentDefault)

                self.imageDetail = UIImage(CGImage: cgImageRef!, scale: 1.0, orientation: UIImageOrientation.Right)

                self.performSegueWithIdentifier("captureSessionDetailSegue", sender: self)
            }
        })
    }
}



override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

override func viewWillDisappear(animated: Bool) {
    captureSession!.stopRunning()
    self.navigationController?.setNavigationBarHidden(false, animated: false)

}

override func viewWillAppear(animated: Bool) {

    super.viewWillAppear(animated)

    // display properties
    self.navigationController?.setNavigationBarHidden(true, animated: false)

    captureSession = AVCaptureSession()
    captureSession!.sessionPreset = AVCaptureSessionPresetPhoto

    let backCamera = AVCaptureDevice.defaultDeviceWithMediaType(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 && captureSession!.canAddInput(input) {
        captureSession!.addInput(input)

        stillImageOutput = AVCaptureStillImageOutput()
        stillImageOutput!.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]

        if captureSession!.canAddOutput(stillImageOutput) {
            captureSession!.addOutput(stillImageOutput)

            previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)


            previewLayer!.videoGravity = AVLayerVideoGravityResizeAspectFill
            previewLayer!.connection?.videoOrientation = AVCaptureVideoOrientation.Portrait



            previewLayerView.layer.addSublayer(previewLayer!)
            //previewLayerView.layer.removeAllAnimations()


            captureSession!.startRunning()
        }
    }

}
override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    previewLayer!.frame = previewLayerView.bounds
}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}



// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.

    //if segue.identifier == "captureSessionDetailSegue" {

    let destination = segue.destinationViewController as! CaptureSessionDetailViewController
    destination.capturedImage.image = self.imageDetail

    // returns nil propertyfrom here
    //destination.navigationController!.setNavigationBarHidden(true, animated: false)
    //}
}


}

Here is the DetailViewController?

class CaptureSessionDetailViewController: UIViewController {

@IBOutlet var capturedImage: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}
*/

}

My current code yields fatal error: unexpectedly found nil while unwrapping an Optional value. I think its because of my prepareForSegue method setting something that is not present yet but I do not know how to get the image to the desired DetailViewController.

How can I achieve my desired results?

Dharmesh Kheni · Accepted Answer

Don't assign image Directly like:

destination.capturedImage.image = self.imageDetail

But declare another instance which will hold your image into CaptureSessionDetailViewController like shown below:

var capturedImageRef = UIImage()

Now you can assign image to CaptureSessionDetailViewController from AddPhotoViewController this way into your Segue method:

destination.capturedImageRef = self.imageDetail

Now in viewDidLoad of CaptureSessionDetailViewController you can assign that image to imageView:

capturedImage.image = capturedImageRef

How to capture a still image with AVFoundation and display the image in another view controller using Swift

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