我正在制作iPhone应用程序并使用S3存储图像,现在我想下载它们并在我的应用程序中显示它们。问题是我在显示图像之前就进行了AWSS3TransferManagerDownloadRequest。问题出在这里:我第一次想要显示图像时,它并没有显示出来,大概是因为下载请求还没有完成。之后,每当我重新运行我的项目时,图像都显示正常,大概是因为它已经存储在本地。那么我该如何让图像立刻显示出来。这是相关的功能。
- (void)makeImageWithBucket:(NSString *)bucket withKey:(NSString *)key atLocation:(NSString *)location{
AWSS3TransferManager *transferManager = [AWSS3TransferManager defaultS3TransferManager];
// Construct the NSURL for the download location.
NSString *downloadingFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:location];
NSURL *downloadingFileURL = [NSURL fileURLWithPath:downloadingFilePath];
// Construct the download request.
AWSS3TransferManagerDownloadRequest *downloadRequest = [AWSS3TransferManagerDownloadRequest new];
downloadRequest.bucket = bucket;
downloadRequest.key = key;
downloadRequest.downloadingFileURL = downloadingFileURL;
// Download the file.
[[transferManager download:downloadRequest] continueWithExecutor:[AWSExecutor mainThreadExecutor]
withBlock:^id(AWSTask *task) {
if (task.error){
if ([task.error.domain isEqualToString:AWSS3TransferManagerErrorDomain]) {
switch (task.error.code) {
case AWSS3TransferManagerErrorCancelled:
case AWSS3TransferManagerErrorPaused:
break;
default:
NSLog(@"Error: %@", task.error);
break;
}
} else {
// Unknown error.
NSLog(@"Error: %@", task.error);
}
}
if (task.result) {
AWSS3TransferManagerDownloadOutput *downloadOutput = task.result;
//File downloaded successfully.
}
return nil;
}];
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 375, 667)];
imageView.image = [UIImage imageWithContentsOfFile:downloadingFilePath];
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame: self.view.frame];
scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
scrollView.contentSize = CGSizeMake(375,imageView.frame.size.height);
[scrollView addSubview:imageView];
[self.view addSubview:scrollView];}
答案 0 :(得分:1)
您可以通过'继续'来更新用户界面。块。因此,如果您显示的图片是nil
,则可以在代码段的这一部分进行更新:
if (task.result) {
AWSS3TransferManagerDownloadOutput *downloadOutput = task.result;
//File downloaded successfully.
//Display the downloaded image here.
}