Extension (iOS)/PhotoEditingViewController.swift

/*
 Copyright (C) 2016 Apple Inc. All Rights Reserved.
 See LICENSE.txt for this sample’s licensing information
 
 Abstract:
 This view controller provides the UI for the photo edting extension in iOS.
 */
 
import UIKit
import Photos
import PhotosUI
 
class PhotoEditingViewController: UIViewController, ContentEditingDelegate {
 
    @IBOutlet weak var previewImageView: UIImageView!
    @IBOutlet weak var backgroundImageView: UIImageView!
    @IBOutlet weak var collectionView: UICollectionView!
    @IBOutlet weak var livePhotoView: PHLivePhotoView!
 
    // Shared object to handle editing in both iOS and OS X
    lazy var editController = ContentEditingController()
 
    // ContentEditingDelegate callbacks to UI
    var preselectedFilterIndex: Int?
    var previewImage: CIImage?
    var previewLivePhoto: PHLivePhoto? {
        didSet {
            livePhotoView.livePhoto = previewLivePhoto
            livePhotoView.contentMode = .scaleAspectFit
        }
    }
 
    override func viewDidLoad() {
        super.viewDidLoad()
        editController.delegate = self
    }
 
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
 
        if let index = preselectedFilterIndex {
            let indexPath = IndexPath(row: index, section: 0)
            collectionView!.selectItem(at: indexPath, animated: true, scrollPosition: .centeredHorizontally)
            updateSelection(for: collectionView.cellForItem(at: indexPath)!)
        }
    }
}
 
// MARK: PHContentEditingController
extension PhotoEditingViewController: PHContentEditingController {
 
    // Forward all methods to shared implementation for both platforms.
 
    func canHandle(_ adjustmentData: PHAdjustmentData) -> Bool {
        return editController.canHandle(adjustmentData)
    }
    
    func startContentEditing(with contentEditingInput: PHContentEditingInput, placeholderImage: UIImage) {
 
        // Except here: show the image preview before forwarding.
        previewImageView.image = placeholderImage
        backgroundImageView.image = placeholderImage
        collectionView.reloadData()
 
        editController.startContentEditing(with: contentEditingInput)
    }
    
    func finishContentEditing(completionHandler: @escaping (PHContentEditingOutput?) -> Swift.Void) {
        editController.finishContentEditing(completionHandler: completionHandler)
    }
    
    var shouldShowCancelConfirmation: Bool {
        return editController.shouldShowCancelConfirmation
    }
    
    func cancelContentEditing() {
        editController.cancelContentEditing()
    }
 
}
 
// Cell class for collection view
class PhotoFilterCell: UICollectionViewCell {
    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet weak var filterNameLabel: UILabel!
}
 
// MARK: UICollectionViewDataSource
extension PhotoEditingViewController: UICollectionViewDataSource {
 
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return editController.filterNames.count
    }
 
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
 
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: String(describing: PhotoFilterCell.self), for: indexPath) as? PhotoFilterCell
            else { fatalError("unexpected cell in storyboard") }
 
        let filterName = editController.filterNames[indexPath.item]
        if filterName == editController.wwdcFilter {
            cell.filterNameLabel.text = editController.wwdcFilter
        } else {
            // Query Core Image for filter's display name.
            let filter = CIFilter(name: filterName)!
            let filterDisplayName = filter.attributes[kCIAttributeFilterDisplayName]! as! String
            cell.filterNameLabel.text = filterDisplayName
        }
        // Show the preview image defined by the editing controller.
        if let images = editController.previewImages {
            cell.imageView.image = UIImage(ciImage: images[indexPath.item])
        }
 
        return cell
    }
}
 
// MARK: UICollectionViewDelegate
extension PhotoEditingViewController: UICollectionViewDelegate {
 
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        updateSelection(for: collectionView.cellForItem(at: indexPath)!)
 
        let filterName = editController.filterNames[indexPath.item]
        editController.selectedFilterName = filterName
 
        // Edit controller has already defined preview images for all filters,
        // so just switch the big preview to the right one.
        if let images = editController.previewImages {
            previewImage = images[indexPath.item]
            previewImageView.image = UIImage(ciImage: previewImage!)
        }
 
        if #available(iOSApplicationExtension 10.0, *) {
            editController.updateLivePhotoIfNeeded() // applies filter, sets previewLivePhoto on completion
        }
    }
 
    func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
        updateSelection(for: collectionView.cellForItem(at: indexPath)!)
    }
 
    func updateSelection(for cell: UICollectionViewCell) {
        guard let cell = cell as? PhotoFilterCell else { fatalError("unexpected cell") }
 
        cell.imageView.layer.borderColor = view.tintColor.cgColor
        cell.imageView.layer.borderWidth = cell.isSelected ? 2 : 0
 
        cell.filterNameLabel.textColor = cell.isSelected ? view.tintColor : .white
    }
}


Copyright © 2016 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2016-09-13