iOS Swift：AWS SDK – 从S3下载文件 – 获取内容而不保存文件

func downloadImage(key: String){

    var completionHandler: AWSS3TransferUtilityDownloadCompletionHandlerBlock?

    //downloading image


    let S3BucketName: String = "your_s3_bucketName"
    let S3DownloadKeyName: String = key

    let expression = AWSS3TransferUtilityDownloadExpression()
    expression.downloadProgress = {(task: AWSS3TransferUtilityTask,bytesSent: Int64,@R_541_10586@lBytesSent: Int64,@R_541_10586@lBytesExpectedToSend: Int64) in
        dispatch_async(dispatch_get_main_queue(),{
            let progress = Float(@R_541_10586@lBytesSent) / Float(@R_541_10586@lBytesExpectedToSend)
            //self.progressview.progress = progress
            //   self.statusLabel.text = "Downloading..."
            NSLog("Progress is: %f",progress)
        })
    }



    completionHandler = { (task,LOCATIOn,data,error) -> Void in
        dispatch_async(dispatch_get_main_queue(),{
            if ((error) != nil){
                NSLog("Failed with error")
                NSLog("Error: %@",error!);
                //   self.statusLabel.text = "Failed"
            }
                /*
                else if(self.progressview.progress != 1.0) {
                //    self.statusLabel.text = "Failed"
                NSLog("Error: Failed - Likely due to invalid region / filename")
                }   */
            else{
                //    self.statusLabel.text = "success"
                self.collectionImages[S3DownloadKeyName] = UIImage(data: data!)
                //reload the collectionView data to include new picture
                self.colView.reloadData()
            }
        })
    }

    let transferUtility = AWSS3TransferUtility.defaultS3TransferUtility()

    transferUtility.downloadToURL(nil,bucket: S3BucketName,key: S3DownloadKeyName,expression: expression,completionHander: completionHandler).conTinueWithBlock { (task) -> AnyObject! in
        if let error = task.error {
            NSLog("Error: %@",error.localizedDescription);
            //  self.statusLabel.text = "Failed"
        }
        if let exception = task.exception {
            NSLog("Exception: %@",exception.description);
            //  self.statusLabel.text = "Failed"
        }
        if let _ = task.result {
            //    self.statusLabel.text = "StarTing Download"
            //NSLog("Download StarTing!")
            // Do something with uploadTask.
            /*
            dispatch_async(dispatch_get_main_queue(),{
                self.colView.reloadData()
            })
            */

        }
        return nil;
    }

}