ios - 在 swift spritekit 场景中淡化视频

Question

我正在将陈列室应用程序从 as3/starling 移植到本地 swift iPad 应用程序。

我有两个问题:

1. 如何在我的 spritekit 内容上淡化视频(从 alpha 0 到 1)。

2. 如何在不显示 iOS 屏幕音量通知图形的情况下使用单个 UI 元素控制 iPad 音量。

Answer 1

我的第一个答案回答了您最初的问题，这个答案是针对评论中发布的后续问题量身定制的。我觉得这两个答案对社区都有用，而不是合并成一个我认为会造成混淆的答案。

在这里，我实现了一个音量 slider 和一个控制 VideoNode 的 AVPlayer 对象的滑动 slider 。您可以获得 AVPlayer 的全部功能，但具有 SKVideoNode 的便利性。另外，播放视频的音量是可以控制的，无需调整系统音量和随后的灰色弹窗:

import SpriteKit
import MediaPlayer


class GameScene: SKScene {

  let seekSlider = UISlider(frame: CGRect(x: 0, y: 0, width: 200, height: 15))
  let volSlider  = UISlider(frame: CGRect(x: 0, y: 0, width: 200, height: 15))

  // Because it takes time for us to load the video, we don't know it's duration,
  // hence we don't know what the `.maximumValue` should be for the seekSlider
  let defaultMax = Float(0.123456789)

  var player: AVPlayer!
  var videoNode: SKVideoNode!

  func seekSliderChangedValue(sender: UISlider) {
    // Wait for file to finish loading so we can get accurate end duration:
      if sender.maximumValue == defaultMax {
      if CMTimeGetSeconds(player.currentItem!.duration).isNaN { return }
      else { sender.maximumValue = Float(CMTimeGetSeconds(player.currentItem!.duration)) }
    }

    let value = CMTimeMake(Int64(seekSlider.value), 1)
    player.seek(to: value)
    player.play()
  }

  func volSliderChangedValue(sender: UISlider) {
    player.volume = sender.value
  }

  override func didMove(to view: SKView) {
    removeAllChildren()  // Delete this in your actual project.

    // Add some labels:
    let seekLabel = SKLabelNode(text: "Seek")
    seekLabel.setScale(3)
    seekLabel.verticalAlignmentMode = .center
    seekLabel.position = CGPoint(x: frame.minX + seekLabel.frame.width/2,
                                 y: frame.maxY - seekLabel.frame.height)
    let volLabel  = SKLabelNode(text: "Volume")
    volLabel.setScale(3)
    volLabel.verticalAlignmentMode = .center
    volLabel.position = CGPoint(x: frame.minX + volLabel.frame.width/2,
                                y: frame.minY + volLabel.frame.height + volSlider.frame.height)

    // Make player and node:
    let url = Bundle.main.url(forResource: "sample", withExtension: "mp4")!
    player = AVPlayer(url: url)
    videoNode = SKVideoNode(avPlayer: player!)

    //Configure seek slider:
    seekSlider.addTarget(self, action: #selector(seekSliderChangedValue), for: UIControlEvents.valueChanged)
    seekSlider.maximumValue = defaultMax
    let seekOrigin = convertPoint(toView: CGPoint(x: seekLabel.frame.minX, y: seekLabel.frame.minY))
    seekSlider.frame = CGRect(origin: seekOrigin, size: CGSize(width: 200, height: 15))

    //Configure vol slider:
    volSlider.addTarget(self, action: #selector(volSliderChangedValue), for: UIControlEvents.valueChanged)
    volSlider.value = 1
    let volOrigin = convertPoint(toView: CGPoint(x: volLabel.frame.minX, y: volLabel.frame.minY))
    volSlider.frame = CGRect(origin: volOrigin, size: CGSize(width: 200, height: 15))

    //Scene stuff:
    view.addSubview(seekSlider)
    view.addSubview(volSlider)
    addChild(seekLabel)
    addChild(volLabel)
    addChild(videoNode)

    // Start video and animation:
    videoNode.alpha = 0
    videoNode.play()
    videoNode.run(.fadeIn(withDuration: 5))
  }
}