Question

我正在尝试实现多行项目（例如如下所示的Final Cut Pro或Adobe Premiere Pro中的视频编辑序列）。

虽然我总是可以使用UIScrollView来实现它并手动放置自定义视图，但是这特别繁琐，特别是在重新排序项目和动画更改以及使用捏合手势缩放时间轴上。是否可以使用UICollectionViewCompositionalLayout和UICollectionViewDiffableDataSource使用UICollectionView来实现它？从WWDC视频中，似乎几乎可以使用合成布局来实现所有功能，但尚不清楚是否可以使用它来实现时间表。也许UICollectionView不是这种用例的正确范例，应该使用UIScrollView吗？即使我使用UIScrollView，也要管理诸如拖动和重新排序项目，为数据源更改设置动画效果，修剪项目，缩放内容之类的问题。是否有任何指向实现这些功能的现有代码库的指针？

Answer 1

这是我的游乐场代码，它是一个简单的空iOS Playground文件的部分答案。它应该给您一个基本的想法，如何使用SpriteKit来实现它。我没有添加任何动画，到目前为止，场景具有固定的宽度，并且“相机”也已固定，尚不允许缩放。但是我想给你一些东西，以便您可以决定这是否是适合您的解决方案。

import UIKit
import SpriteKit
import PlaygroundSupport

class MyViewController: UIViewController {
    
    override func loadView() {
        
        // Setting up a basic UIView as parent
        let parentView = UIView()
        parentView.frame = CGRect(x: 0, y: 0, width: 600, height: 600)
        parentView.backgroundColor = .black
        
        // Defining the SKView
        let tracksSKView = SKView(frame: parentView.frame)
        
        tracksSKView.ignoresSiblingOrder = false
        
        // Options to debug visually
//      tracksSKView.showsNodeCount = true
//      tracksSKView.showsPhysics = true
//      tracksSKView.showsFields = true
//      tracksSKView.showsLargeContentViewer = true
        
        // Defining our subclassed SKScene
        let scene = GameScene(size: tracksSKView.bounds.size)
        
        // Presenting and adding views and sceens
        tracksSKView.presentScene(scene)
        parentView.addSubview(tracksSKView)
        self.view = parentView
    }
    
}

//MARK: - Custom SKScene

class GameScene: SKScene {
    
    let trackSize = CGSize(width: 2048, height: 120)
    let tracksCount = 4
        
    
    // Hardcoded clips, use your data source and update when a clip has been moved in any way.
    let clips: [Clip] = [
        Clip(name: "SongA", track: 1, xPosition: 0, lengh: 245),
        Clip(name: "SongB", track: 2, xPosition: 200, lengh: 166, color: .blue),
        Clip(name: "SongC", track: 3, xPosition: 200, lengh: 256, color: .red)
    ]
        
    var touchingClip = false
    var touchedClip = SKNode()
    
    // Bacically like loadView or viewDidLoad
    override func didMove(to view: SKView) {
        
        physicsWorld.contactDelegate = self
        
        self.size = CGSize(width: 1024, height: 768)
        self.name = "scene"
        
        addTracks(amount: tracksCount)
        addClips(clips: clips)
    }
    
    // Adding x amount of tracks.
    func addTracks(amount: Int) {
        for n in 0..<amount {
            
            let trackNode = SKSpriteNode(color: n%2 == 0 ? .systemGray : .systemGray2, size: trackSize)
            
            // Setting up physical propeties of the border of the track
            trackNode.physicsBody = SKPhysicsBody(edgeLoopFrom: trackNode.frame)
            trackNode.physicsBody?.restitution = 0.2
            trackNode.physicsBody?.allowsRotation = false
            trackNode.physicsBody?.affectedByGravity = false
            trackNode.physicsBody?.isDynamic = false
            
            // Positioning the track
            trackNode.zPosition = -1
            trackNode.position.y = frame.minY + trackSize.height / 2 + CGFloat(n) * trackSize.height
            
            addChild(trackNode)
        }
    }
    
    // Adding the Clip objects stored in an array.
    func addClips(clips: [Clip]) {
        for clip in clips {
            let clipNode = SKSpriteNode(color: clip.color, size: CGSize(width: clip.lengh, height: Int(trackSize.height) - 20))
            
            clipNode.position.x = clip.xPosition + CGFloat(clip.lengh / 2)
            clipNode.position.y = frame.minY + (trackSize.height * CGFloat(clip.track)) + 1
            clipNode.zPosition = 1
            
            clipNode.physicsBody = SKPhysicsBody(rectangleOf: clipNode.frame.size)
            clipNode.physicsBody?.affectedByGravity = true
            clipNode.physicsBody?.allowsRotation = false
            clipNode.physicsBody?.restitution = 0.2
            
            addChild(clipNode)
        }
        
    }
    
    //MARK: - User interaction
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        for touch in touches {
            let location = touch.location(in: self)
            
            // getting all nodes the user touched (visible and hidden below others.
            let tappedNodes = nodes(at: location)
            
            //getting the top node
            if let node = tappedNodes.first {
                touchedClip = node
                touchingClip = true
            }
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        guard touchingClip else { return }
        
        // Moving the clip (node) based on the movement of the touch. It's very basic and can look jittery. Using the animate methods would create better results.
        for touch in touches {
            let location = touch.location(in: self)
            
            touchedClip.position = location
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        touchingClip = false
    }
    
}

//MARK: - Interaction in between object like collisions etc.

extension GameScene: SKPhysicsContactDelegate {
    // handle different contact cases here
}

//MARK: - Clip object

struct Clip {
    var name: String
    var track: Int
    var xPosition: CGFloat
    var lengh: Int
    var color: UIColor = .green
}


PlaygroundPage.current.liveView = MyViewController()

我添加了一个手势识别器，可以长按以移动剪辑，而触摸和平移不会调整剪辑的大小。这是新代码：

import UIKit
import SpriteKit
import PlaygroundSupport

PlaygroundPage.current.liveView = MyViewController()

class MyViewController: UIViewController {
    
    override func loadView() {
        
        // Setting up a basic UIView as parent
        let parentView = UIView()
        parentView.frame = CGRect(x: 0, y: 0, width: 600, height: 600)
        parentView.backgroundColor = .black
        
        // Defining the SKView
        let tracksSKView = SKView(frame: parentView.frame)
        
        tracksSKView.ignoresSiblingOrder = false
        
        // Options to debug visually
        tracksSKView.showsNodeCount = true
        tracksSKView.showsPhysics = true
        tracksSKView.showsFields = true
        tracksSKView.showsLargeContentViewer = true
        
        // Defining our subclassed SKScene
        let scene = GameScene(size: tracksSKView.bounds.size)
        
        // Presenting and adding views and sceens
        tracksSKView.presentScene(scene)
        parentView.addSubview(tracksSKView)
        self.view = parentView
    }
}

//MARK: - Custom SKScene

class GameScene: SKScene {
    
    let trackSize = CGSize(width: 2048, height: 120)
    let tracksCount = 4
    
    // Hardcoded clips, use your data source and update when a clip has been moved in any way.
    let clips: [Clip] = [
        Clip(name: "SongA", track: 1, xPosition: 0, lengh: 245),
        Clip(name: "SongB", track: 2, xPosition: 200, lengh: 166, color: .blue),
        Clip(name: "SongC", track: 3, xPosition: 200, lengh: 256, color: .red)
    ]
    
    // Different interactions, I used a sepperate variable for each interaction instead of one to be able to add more later.
    var touchingClip = false
    var movingClip = false
    var resizingClip = true
    
    var touchedClip = SKNode()
    var location = CGPoint()
    
    // Bacically like loadView or viewDidLoad
    override func didMove(to view: SKView) {
        
        physicsWorld.contactDelegate = self
        
        // Using the UI gesture recognizer in the case of a long press seemed easier than trying to figure out the gestures in the touches methods.
        let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(GameScene.longPress))
        self.view!.addGestureRecognizer(longPressRecognizer)
        
        // Adding tracks and clips
        addTracks(amount: tracksCount)
        addClips(clips: clips)
    }
    
    // Method that handles the long press
    @objc func longPress(sender: UILongPressGestureRecognizer) {
        if sender.state == .began || sender.state == .changed {
            movingClip = true
            resizingClip = false
        } else {
            movingClip = false
            resizingClip = true
        }
        location = sender.location(in: self.view)
    }
    
    //MARK: - Setting up the tracks and clips
    
    // Adding x amount of tracks.
    func addTracks(amount: Int) {
        for n in 0..<amount {
            
            let trackNode = SKSpriteNode(color: n%2 == 0 ? .systemGray : .systemGray2, size: trackSize)
            
            // Setting up physical propeties of the border of the track
            trackNode.physicsBody = SKPhysicsBody(edgeLoopFrom: trackNode.frame)
            trackNode.physicsBody?.restitution = 0.2
            trackNode.physicsBody?.allowsRotation = false
            trackNode.physicsBody?.affectedByGravity = false
            trackNode.physicsBody?.isDynamic = false
            
            // Positioning the track
            trackNode.zPosition = -1
            trackNode.position.y = frame.minY + trackSize.height / 2 + CGFloat(n) * trackSize.height
            
            addChild(trackNode)
        }
    }
    
    // Adding the Clip objects stored in an array.
    func addClips(clips: [Clip]) {
        for clip in clips {
            let clipNode = SKSpriteNode(color: clip.color, size: CGSize(width: clip.lengh, height: Int(trackSize.height) - 20))
            clipNode.name = clip.name
            clipNode.position.x = clip.xPosition + CGFloat(clip.lengh / 2)
            clipNode.position.y = frame.minY + (trackSize.height * CGFloat(clip.track)) + 1
            clipNode.zPosition = 1
            
            clipNode.physicsBody = SKPhysicsBody(rectangleOf: clipNode.frame.size)
            clipNode.physicsBody?.affectedByGravity = true
            clipNode.physicsBody?.allowsRotation = false
            clipNode.physicsBody?.restitution = 0.2
            clipNode.physicsBody?.isDynamic = true
            
            addChild(clipNode)
        }
    }
    
    //MARK: - User interaction
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        guard touches.first != nil else { return }
        
        for touch in touches {
            let location = touch.location(in: self)
            touchedClip = atPoint(location) as! SKSpriteNode
            if clips.contains(where: { $0.name == touchedClip.name }) {
                touchingClip = true
            }
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        guard touchingClip else { return }
        
        for touch in touches {
            
            if resizingClip {
                let resizeValue = touch.location(in: touchedClip).x - touch.previousLocation(in: touchedClip).x
                
                // Checking that we're only adding width to the clip or trimming no more then the remaining width.
                if resizeValue > 0 || (resizeValue < 0 && abs(resizeValue) < touchedClip.frame.size.width) {
                    let action = SKAction.resize(byWidth: resizeValue, height: 0, duration: 0.0)
                    action.timingMode = .linear
                    touchedClip.run(action)
                }
            }
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        touchingClip = false
        resizingClip = true
        movingClip = false
    }
    
    //MARK: - Scene update
    
    // Runs as long as scene is active once per frame (target of 60 frames per second)
    override func update(_ currentTime: TimeInterval) {
        
        // The moving needs to be done in the update method, the touches methods are unresponsive while the gesture recognizer is active.
        if movingClip && touchingClip {
            let newLocation = convertPoint(fromView: location)
            let action = SKAction.move(to: newLocation, duration: 0.1)
            action.timingMode = .easeInEaseOut
            touchedClip.run(action)
        }
        
        // The physics body does not change when the clip node is resized. I'm updating it here.
        if resizingClip && touchingClip {
            touchedClip.physicsBody = SKPhysicsBody(rectangleOf: touchedClip.frame.size)
            touchedClip.physicsBody?.affectedByGravity = true
            touchedClip.physicsBody?.allowsRotation = false
            touchedClip.physicsBody?.restitution = 0.2
            touchedClip.physicsBody?.isDynamic = true
        }
    }
}

//MARK: - Interaction in between object like collisions etc.

extension GameScene: SKPhysicsContactDelegate {
    // handle different contact cases here
}

//MARK: - Clip object

struct Clip {
    var name: String
    var track: Int
    var xPosition: CGFloat
    var lengh: Int
    var color: UIColor = .green
}

来源：

www.udemy.com/course/dive-into-spritekit（很好，但不是很好）

designcode.io（不推荐）

stackoverflow.com/questions/30337608/detect-long-touch-in-sprite-kit

以及更多的SO和Apple Dev：）

UICollectionView用于非网格或半网格布局

1 个答案: