视频缩略图需要10-15秒才能显示 [英] Video thumbnail taking 10-15 secs to display

问题描述

我正在使用DKImagePickerController从图库中选择视频并尝试显示它的缩略图。不知道为什么，但显示图像需要10-15秒。任何帮助表示赞赏。

I am using DKImagePickerController to select the video from gallery and trying to show a thumbnail of it. Don't know why, but it's taking 10-15 sec to display the image. Any help is appreciated.

以下是代码：

tempDkAsset.fetchAVAssetWithCompleteBlock { (tempVideo, info) in

    tempImageView.image = self.thumbnailForVideoAtURL(tempVideo!)  
}





func thumbnailForVideoAtURL(_ asset : AVAsset) -> UIImage? {

    let assetImageGenerator = AVAssetImageGenerator(asset: asset)

    var time = asset.duration
    time.value = min(time.value, 2)

    do {
        let imageRef = try assetImageGenerator.copyCGImage(at: time, actualTime: nil)
        return UIImage(cgImage: imageRef)
    } catch {
        print("error")
        return nil
    }
}

推荐答案

问题是您在后台线程上调用 thumbnailForVideoAtURL 。你需要在主线程上，因为你正在与界面交谈。

The problem is that you are calling thumbnailForVideoAtURL on a background thread. You need to be on the main thread because you are talking to the interface.

tempDkAsset.fetchAVAssetWithCompleteBlock { (tempVideo, info) in
    DispatchQueue.main.async {
        tempImageView.image = self.thumbnailForVideoAtURL(tempVideo!)
    }
}  

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