Activity 指标在 PHPhotoLibrary.sharedPhotoLibrary().performChanges 内部动作缓慢

Question

我正在删除一些照片资产，我想在资产被删除时显示一个 activity 指示器，并在资产被删除但我的代码运行缓慢时停止它，你知道吗错了吗？

PHPhotoLibrary.sharedPhotoLibrary().performChanges({
            PHAssetChangeRequest.deleteAssets(enumeration)
            self.activityIndicator.startAnimating()
            UIApplication.sharedApplication().beginIgnoringInteractionEvents()
            }, completionHandler: {success, error in
                if success {
                    self.activityIndicator.stopAnimating()
                    UIApplication.sharedApplication().endIgnoringInteractionEvents()
                    println("Success")
                } else {
                    self.activityIndicator.stopAnimating()
                    UIApplication.sharedApplication().endIgnoringInteractionEvents()
                    println("Error")
                }
        })

Answer 1

我自己解决了，这里是答案：

PHPhotoLibrary.sharedPhotoLibrary().performChanges({
            PHAssetChangeRequest.deleteAssets(enumeration)

            let delay = 1 * Double(NSEC_PER_SEC)
            let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
            dispatch_after(time, dispatch_get_main_queue()) {
                self.activityIndicator.startAnimating()
            }
            }, completionHandler: {success, error in

                UIApplication.sharedApplication().beginIgnoringInteractionEvents()

                if success {
                    println("good")
                    dispatch_async(dispatch_get_main_queue()){
                        self.activityIndicator.stopAnimating()
                        self.navigationController?.popToRootViewControllerAnimated(true)
                    }
                    UIApplication.sharedApplication().endIgnoringInteractionEvents()
                } else {
                    println("bad")
                    dispatch_async(dispatch_get_main_queue()){
                        self.activityIndicator.stopAnimating()
                    }
                    UIApplication.sharedApplication().endIgnoringInteractionEvents()
                }
        })

只需添加：

dispatch_async(dispatch_get_main_queue()){
     self.activityIndicator.stopAnimating()
}