Creating a Custom Camera View - sammanthp007/Linux-Kernel-Development GitHub Wiki

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 session: AVCaptureSession?
var stillImageOutput: AVCapturePhotoOutput?
var videoPreviewLayer: AVCaptureVideoPreviewLayer?

Step 5: Create a viewWillAppear Method

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

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

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

Step 6: Setup Session

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

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

session = AVCaptureSession()
session!.sessionPreset = AVCaptureSessionPresetPhoto

• NOTE: If you plan to upload your photo to Parse, you will likely need to change your preset to AVCaptureSessionPresetHigh or AVCaptureSessionPresetMedium 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.

let backCamera = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)

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.

var error: NSError?
var input: AVCaptureDeviceInput!
do {
  input = try AVCaptureDeviceInput(device: backCamera)
} catch let error1 as NSError {
  error = error1
  input = nil
  print(error!.localizedDescription)
}

Step 9: Attach the Input

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

if error == nil && session!.canAddInput(input) {
  session!.addInput(input)
  // ...
  // The remainder of the session setup will go here...
}

Step 10: Configure the Output

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

• Create a new AVCaptureStillImageOutput object.
• Set the output data setting to use JPEG format.

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

Step 11: Attach the Output

If the session is able to accept our output, then we will attach the output to the session.

if session!.canAddOutput(stillImageOutput) {
  session!.addOutput(stillImageOutput)
  // ...
  // Configure the Live Preview here... 
}

Step 12: 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!

videoPreviewLayer = AVCaptureVideoPreviewLayer(session: session)
videoPreviewLayer!.videoGravity = AVLayerVideoGravityResizeAspect
videoPreviewLayer!.connection?.videoOrientation = AVCaptureVideoOrientation.Portrait
previewView.layer.addSublayer(videoPreviewLayer!)
session!.startRunning()

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

• Create a viewDidAppear method. just like with the viewWillAppear method, we will want to call the super. of the viewDidAppear method.
• Within the viewDidAppear method, set the size and origin of the Preview Layer to fit inside the Preview View. We will do this using the bounds property.

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

Step 14: 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.

Snap a Photo

Step 1: Get the Connection

• Get the connection from the stillImageOutput.

if let videoConnection = stillImageOutput!.connectionWithMediaType(AVMediaTypeVideo) {
  // ...
  // Code for photo capture goes here...
}

Step 2: Capture the Photo

• Call the captureStillImageAsynchronouslyFromConnection function on the stillImageOutput.
• The sampleBuffer represents the data that is captured.

stillImageOutput?.captureStillImageAsynchronouslyFromConnection(videoConnection, completionHandler: { (sampleBuffer, error) -> Void in
  // ...
  // Process the image data (sampleBuffer) here to get an image file we can put in our captureImageView
})

Step 3: Process the Image Data

• We will need to to take a few steps to process the image data found in sampleBuffer in order to end up with a UIImage that we can insert into our captureImageView and easily use elsewhere in our app.

if sampleBuffer != nil {
  let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(sampleBuffer)
  let dataProvider = CGDataProviderCreateWithCFData(imageData)
  let cgImageRef = CGImageCreateWithJPEGDataProvider(dataProvider, nil, true, CGColorRenderingIntent.RenderingIntentDefault)
  let image = UIImage(CGImage: cgImageRef!, scale: 1.0, orientation: UIImageOrientation.Right)
  // ...
  // Add the image to captureImageView here...
}

ATTENTION: pay attention here. We are generating a rotated UIImage instance, but the backed CGImage will still be rotated in the wrong way.

Step 4: Add the Image to the ImageView

• Finally, add the image to captureImageView.

self.captureImageView.image = image

Step 5: 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 and the ability to "Snap" a photo and see the still image within your captureImageView.
• NOTE: We are just adding the image to the captureImageView to illustrate the technique of capturing a still image. Once you have the still image you can do all kinds of cool things, like save it into your photo library, or upload it to Parse for use elsewhere in your app.