Helper class to ask for the user to pick/take a photo.

GSPhotoPicker.swift

//
//  GSPhotoPicker.swift
//  TeamKnect
//
//  Created by Scott Grosch on 10/18/14.
//  Copyright (c) 2014 Gargoyle Software, LLC. All rights reserved.
//

import UIKit

final class GSPhotoPicker: NSObject {
    private let onImagePicked: (UIImage?) -> Void
    
    private weak var presentingViewController: UIViewController?
    private weak var presentingView: UIView?
    
    init(view: UIView, viewController: UIViewController, onImagePicked: (UIImage?) -> Void) {
        self.onImagePicked = onImagePicked
        presentingViewController = viewController
        presentingView = view
    }
    
    func showImagePicker() {
        let camera = UIImagePickerController.isSourceTypeAvailable(.Camera)
        let library = UIImagePickerController.isSourceTypeAvailable(.PhotoLibrary)
        
        if library && camera {
            let sheet = UIAlertController(title: nil, message: nil, preferredStyle: .ActionSheet)
            
            sheet.addAction(UIAlertAction(title: NSLocalizedString("TAKE_PHOTO", comment: "Action button to take photo"), style: .Default) {
                [unowned self] _ in
                self.presentImagePicker(.Camera)
                })
            
            sheet.addAction(UIAlertAction(title: NSLocalizedString("CHOOSE_PHOTO", comment: "Action button to choose existing photo"), style: .Default) {
                [unowned self] _ in
                self.presentImagePicker(.PhotoLibrary)
                })
            
            sheet.addAction(UIAlertAction(title: NSLocalizedString("Cancel", comment: "The cancel button"), style: .Cancel, handler: nil))
            
            presentingViewController?.presentViewController(sheet, animated: true, completion: nil)
        } else if camera {
            presentImagePicker(.Camera)
        } else if library {
            presentImagePicker(.PhotoLibrary)
        }
    }
    
    private func presentImagePicker(sourceType: UIImagePickerControllerSourceType) {
        if let presentingView = presentingView, presentingViewController = presentingViewController {
            let camera = UIImagePickerController()
            camera.sourceType = sourceType
            camera.delegate = self
            camera.allowsEditing = true
            
            if sourceType == .PhotoLibrary {
                // Documentation says picking from photo library on iPad must use popover.
                if let popover = camera.popoverPresentationController {
                    camera.modalPresentationStyle = .Popover
                    
                    popover.permittedArrowDirections = .Any
                    popover.sourceView = presentingView
                    popover.sourceRect = presentingView.frame
                }
            } else if sourceType == .Camera && UIImagePickerController.isCameraDeviceAvailable(.Front) {
                camera.cameraDevice = .Front
            }
            
            presentingViewController.presentViewController(camera, animated: true, completion: nil)
        }
    }
}

// MARK: - UIImagePickerControllerDelegate
extension GSPhotoPicker: UINavigationControllerDelegate, UIImagePickerControllerDelegate {
    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
        presentingViewController?.dismissViewControllerAnimated(true, completion: nil)
        
        let image = (info[UIImagePickerControllerEditedImage] ?? info[UIImagePickerControllerOriginalImage]) as! UIImage
        
        onImagePicked(image)
    }
    
    func imagePickerControllerDidCancel(picker: UIImagePickerController) {
        presentingViewController?.dismissViewControllerAnimated(true, completion: nil)
        onImagePicked(nil)
    }
}