swift - 如何快速实现 AVAssetImageGenerator.copyCGImageAtTime

Question

到目前为止，我有以下内容

  let assetUrl = NSURL.URLWithString(self.targetVideoString)
  let asset: AVAsset = AVAsset.assetWithURL(assetUrl) as AVAsset
  let imageGenerator = AVAssetImageGenerator(asset: asset);
  let time : CMTime = CMTimeMakeWithSeconds(1.0, 1)
  let actualTime : CMTime
  let myImage: CGImage =imageGenerator.copyCGImageAtTime(requestedTime: time, actualTime:actualTime, error: <#NSErrorPointer#>)

最后一行是我迷路的地方......我只是想在 1.0 秒的时间抓取一张图像

Answer 1

函数声明为

func copyCGImageAtTime(requestedTime: CMTime, actualTime: UnsafeMutablePointer<CMTime>, error outError: NSErrorPointer) -> CGImage!

并且您必须使用 & 将(初始化的)CMTime 和 NSError? 变量作为“in-out 表达式”传递:

let assetUrl = NSURL(string: ...)
let asset: AVAsset = AVAsset.assetWithURL(assetUrl) as AVAsset
let imageGenerator = AVAssetImageGenerator(asset: asset);
let time = CMTimeMakeWithSeconds(1.0, 1)

var actualTime : CMTime = CMTimeMake(0, 0)
var error : NSError?
let myImage = imageGenerator.copyCGImageAtTime(time, actualTime: &actualTime, error: &error)

还要注意你的第一行

let assetUrl = NSURL.URLWithString(self.targetVideoString)

不再使用当前的 Xcode 6.1 进行编译。