Creating a Custom Camera View

Accessing the Built in Image Picker Controller is a quick and easy way to get image and video capture into your app. However, when you need style and functionality that goes beyond the stock Image Picker Controller you will need to create a Custom Camera View.

Live Camera Preview

Step 1: Set Up Views In Storyboard

Add the following view elements to the ViewController in Storyboard:

• UIView This will serve as the "view finder" of your camera.
• UIImageView This will hold the captured still image after you take a picture.
• UIButton This button will "take a picture".

Step 2: Import AVFoundation

At the top of your ViewController file, import AVFoundation

Step 3: Create Outlets and Actions

Create Outlets for the UIView and UIImageView.

• Name the UIView, previewView.
• Name the UIImageView, captureImageView.

Create an Action for the UIButton.

• Name the method, didTakePhoto.

Step 4: Define Instance Variables

Above the viewDidLoad method, where you create variables you want to be accessible anywhere in the ViewController file, create the following Instance Variables.

var captureSession: AVCaptureSession!
var stillImageOutput: AVCapturePhotoOutput!
var videoPreviewLayer: AVCaptureVideoPreviewLayer!

@interface CameraViewController ()
@property (nonatomic) AVCaptureSession *captureSession;
@property (nonatomic) AVCapturePhotoOutput *stillImageOutput;
@property (nonatomic) AVCaptureVideoPreviewLayer *videoPreviewLayer;
@end

Step 5: Create a viewDidAppear Method

The bulk of the camera setup will happen in the viewDidAppear.

• NOTE: Make sure to call super.viewDidAppear(animated) also.

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    // Setup your camera here...
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];    
    // Setup your camera here...
}

Step 6: Setup Session

The session will coordinate the input and output data from the devices camera.
Still in viewDidAppear

• Create a new session
• Configure the session for high resolution still photo capture. We'll use a convenient preset to that.

captureSession = AVCaptureSession()
captureSession.sessionPreset = .medium

self.captureSession = [AVCaptureSession new];
self.captureSession.sessionPreset = AVCaptureSessionPresetPhoto;

• NOTE: If you plan to upload your photo to Parse, you will likely need to change your preset to AVCaptureSession.Preset.High or AVCaptureSession.Preset.medium to keep the size under the 10mb Parse max.

Step 7: Select Input Device

In this example, we will be using the rear camera. The front camera and microphone are additional input devices at your disposal. Printing debug comment incase the fetching the rear camera fails. Still in viewDidAppear

guard let backCamera = AVCaptureDevice.default(for: AVMediaType.video)
    else {
        print("Unable to access back camera!")
        return
}

AVCaptureDevice *backCamera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (!backCamera) {
    NSLog(@"Unable to access back camera!");
    return;
}

Step 8: Prepare the Input

We now need to make an AVCaptureDeviceInput. The AVCaptureDeviceInput will serve as the "middle man" to attach the input device, backCamera to the session.

• We will make a new AVCaptureDeviceInput and attempt to associate it with our backCamera input device.
• There is a chance that the input device might not be available, so we will set up a try catch to handle any potential errors we might encounter. In Objective C, errors will be using the traditional NSError pattern. Still in viewDidAppear

do {
    let input = try AVCaptureDeviceInput(device: backCamera)
    //Step 9
}
catch let error  {
    print("Error Unable to initialize back camera:  \(error.localizedDescription)")
}

NSError *error;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:backCamera
                                                                    error:&error];
if (!error) {
    //Step 9
}
else {
    NSLog(@"Error Unable to initialize back camera: %@", error.localizedDescription);
}

Step 9: Configure the Output

Just like we created an AVCaptureDeviceInput to be the "middle man" to attach the input device, we will use AVCapturePhotoOutput to help us attach the output to the session.

• Create a new AVCapturePhotoOutput object.

stillImageOutput = AVCapturePhotoOutput()

self.stillImageOutput = [AVCapturePhotoOutput new];

Step 10: Attach the Input and Output

If there are no errors from our last step and the session is able to accept input and output, the go ahead and add input add output to the Session.

stillImageOutput = AVCapturePhotoOutput()

if captureSession.canAddInput(input) && captureSession.canAddOutput(stillImageOutput) {
    captureSession.addInput(input)
    captureSession.addOutput(stillImageOutput)
    setupLivePreview()
}

self.stillImageOutput = [AVCapturePhotoOutput new];

if ([self.capturesSession canAddInput:input] && [self.capturesSession canAddOutput:self.stillImageOutput]) {
    
    [self.capturesSession addInput:input];
    [self.capturesSession addOutput:self.stillImageOutput];
    [self setupLivePreview];
}

Step 11: Configure the Live Preview

Now that the input and output are all hooked up with our session, we just need to get our Live Preview going so we can actually display what the camera sees on the screen in our UIView, previewView.

• Create an AVCaptureVideoPreviewLayer and associate it with our session.
• Configure the Layer to resize while maintaining it's original aspect.
• Fix the orientation to portrait
• Add the preview layer as a sublayer of our previewView
• Finally, start the session!

func setupLivePreview() {
    
    videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    
    videoPreviewLayer.videoGravity = .resizeAspect
    videoPreviewLayer.connection?.videoOrientation = .portrait
    previewView.layer.addSublayer(videoPreviewLayer)
    
    //Step12
}

- (void)setupLivePreview {
    
    self.videoPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.capturesSession];
    if (self.videoPreviewLayer) {
        
        self.videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspect;
        self.videoPreviewLayer.connection.videoOrientation = AVCaptureVideoOrientationPortrait;
        [self.previewView.layer addSublayer:self.videoPreviewLayer];
        
        //Step12
    }
}

Step 12: Start the Session on the background thread

We need to call -startRunning on the session to start the live view. However -startRunning is a blocking method which means it will block the UI if it's running on the main thread. If the session takes a while to start, users would want the UI to be responsive and cancel out of the camera view.

DispatchQueue.global(qos: .userInitiated).async { //[weak self] in
    self.captureSession.startRunning()
    //Step 13
}

dispatch_queue_t globalQueue =  dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
dispatch_async(globalQueue, ^{
    [self.capturesSession startRunning];
    //Step 13
});

Step 13: Size the Preview Layer to fit the Preview View

Once the live view starts let's set the Preview layer to fit, but we must return to the main thread to do so!

DispatchQueue.main.async {
    self.videoPreviewLayer.frame = self.previewView.bounds
}

dispatch_async(dispatch_get_main_queue(), ^{
    self.videoPreviewLayer.frame = self.previewView.bounds;
});

Step 14: Taking the picture

Let's create an IBAction of the Take photo Button and capture a JPEG by calling our instance of AVCapturePhotoOutput or stillImageOut the method func capturePhoto(with:, delegate:) or -capturePhotoWithSettings:delegate:. This method requires us to provide it with a setting and a deleget to deliver the capturedPhoto to. This delegate will be this ViewController so we also need to conform to the protocol AVCapturePhotoCaptureDelegate

class CameraViewControllerSwift: UIViewController, AVCapturePhotoCaptureDelegate {
    ....
    @IBAction func didTakePhoto(_ sender: Any) {
        
        let settings = AVCapturePhotoSettings(format: [AVVideoCodecKey: AVVideoCodecType.jpeg])
        stillImageOutput.capturePhoto(with: settings, delegate: self)
    }
}

//CameraViewController.h
@interface CameraViewController : UIViewController <AVCapturePhotoCaptureDelegate>

//CameraViewController.m
- (IBAction)didTakePhoto:(id)sender {
    
    AVCapturePhotoSettings *settings = [AVCapturePhotoSettings photoSettingsWithFormat:@{AVVideoCodecKey: AVVideoCodecTypeJPEG}];

    [self.stillImageOutput capturePhotoWithSettings:settings delegate:self];
}

Step 15: Process the captured photo!

The AVCapturePhotoOutput will deliver the captured photo to the assigned delegate which is our current ViewController by a delegate method called photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?). The photo is delivered to us as an AVCapturePhoto which is easy to transform into Data/NSData and than into UIImage.

func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
    
    guard let imageData = photo.fileDataRepresentation()
        else { return }
    
    let image = UIImage(data: imageData)
    captureImageView.image = image
}

- (void)captureOutput:(AVCapturePhotoOutput *)output didFinishProcessingPhoto:(AVCapturePhoto *)photo error:(nullable NSError *)error {
    
    NSData *imageData = photo.fileDataRepresentation;
    if (imageData) {
        UIImage *image = [UIImage imageWithData:imageData];
        // Add the image to captureImageView here...
        self.captureImageView.image = image;
    }
}

Step 16: Clean up when the user leaves!

Let's not forget to stop the session when we leave the camera view!

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    self.captureSession.stopRunning()
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self.capturesSession stopRunning];
}

Step 17: Run Your App ON A REAL DEVICE!!!

NOTE: The simulator does NOT have a camera so you need to run your app on an Actual Device to see the magic!

• At this point, you should see a live "video" stream of your phone camera's input within your previewView.