Front facing camera in UIImagePickerController

Question

I am developing the front facing camera app in iPad2 by using the UIImagePickerController.

When I capture the image it\'s shows as flipped from left to

Answer 1

It looks like AVCaptureDeviceDidStartRunningNotification is no longer available as a means of detecting camera device changes. Also, the cameraDevice property on UIImagePickerController doesn't work with KVO. However, it's still possible to detect camera device changes, as shown below (though long-term support for this solution isn't guaranteed as we're using KVO on a property that isn't explicitly marked as KVO-compliant).

import AVFoundation

var context = 0

override func viewDidLoad() {
    super.viewDidLoad()
    // Register for notifications
    let notificationCenter = NSNotificationCenter.defaultCenter()
    notificationCenter.addObserver(self, selector: #selector(handleCaptureSessionDidStartRunning(_:)), name: AVCaptureSessionDidStartRunningNotification, object: nil)
    notificationCenter.addObserver(self, selector: #selector(handleCaptureSessionDidStopRunning(_:)), name: AVCaptureSessionDidStopRunningNotification, object: nil)
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self)
}

func handleCaptureSessionDidStartRunning(notification: NSNotification) {
    guard let session = notification.object as? AVCaptureSession else { return }
    session.addObserver(self, forKeyPath: "inputs", options: [ .Old, .New ], context: &context)
}

func handleCaptureSessionDidStopRunning(notification: NSNotification) {
    guard let session = notification.object as? AVCaptureSession else { return }
    session.removeObserver(self, forKeyPath: "inputs")
}

override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer) {
    if context == &self.context {
        if let inputs = change?[NSKeyValueChangeNewKey] as? [AnyObject], captureDevice = (inputs.first as? AVCaptureDeviceInput)?.device {
            switch captureDevice.position {
            case .Back: print("Switched to back camera")
            case .Front: print("Switched to front camera")
            case .Unspecified: break
            }
        }
    } else {
        super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
    }
}

Swift 4+ version:

import AVFoundation

var context = 0

override func viewDidLoad() {
    super.viewDidLoad()
    // Register for notifications
    NotificationCenter.default.addObserver(forName: NSNotification.Name(rawValue: "AVCaptureSessionDidStartRunningNotification"), object: nil, queue: nil) { (notification) in
            self.handleCaptureSessionDidStartRunning(notification: notification)}
        
    NotificationCenter.default.addObserver(forName: NSNotification.Name(rawValue: "AVCaptureSessionDidStopRunningNotification"), object: nil, queue: nil) { (notification) in
            self.handleCaptureSessionDidStopRunning(notification: notification)}
}

deinit {
    NotificationCenter.default.removeObserver(self)
}

func handleCaptureSessionDidStartRunning(notification: Notification){
    guard let session = notification.object as? AVCaptureSession else { return }
    session.addObserver(self, forKeyPath: "inputs", options: [ .old, .new ], context: &context)
}

func handleCaptureSessionDidStopRunning(notification: Notification){
    guard let session = notification.object as? AVCaptureSession else { return }
    session.removeObserver(self, forKeyPath: "inputs")
}

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if context == &self.context {
        if let inputs = change?[NSKeyValueChangeKey.newKey] as? [AnyObject], let captureDevice = (inputs.first as? AVCaptureDeviceInput)?.device {
            switch captureDevice.position {
            case .back: print("Switched to back camera")
            case .front: print("Switched to front camera")
            case .unspecified: break
            }
        }
    } else {
        super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
    }
}