如何从AmazonS3-iOS下载

我试图从我的AmazonS3存储桶（v2）下载一个图像，但我想不出来。我一直从[transferManager下载：downloadRequest]获取空值

已填写所有帐户详细信息/密钥。感谢您的帮助

-(void) startApp:(NSDictionary *)launchOptions {
// create credentials
AWSCognitoCredentialsProvider *credentialsProvider = [AWSCognitoCredentialsProvider credentialsWithRegionType:AWSRegionUSEast1
                                                                                                accountId:@"xxxx-xxxx-xxxx"
                                                                                               identityPoolId: @"us-east-1:xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx"
                                                                                                unauthRoleArn:@"Cognito_AppUnauth_DefaultRole"
                                                                                                  authRoleArn:nil];
AWSServiceConfiguration *configuration = [AWSServiceConfiguration configurationWithRegion:AWSRegionUSEast1
                                                                      credentialsProvider:credentialsProvider];
[AWSServiceManager defaultServiceManager].defaultServiceConfiguration = configuration;
}

- (instancetype) init {
AWSS3TransferManagerDownloadRequest *downloadRequest = [AWSS3TransferManagerDownloadRequest new];
downloadRequest.bucket = @"mybucket.s3.amazonaws.com";
downloadRequest.key = @"XXXXXXXXXXXXXXX";
downloadRequest.downloadingFileURL = [NSURL URLWithString:@"https://s3.amazonaws.com/MYBUCKET/hello.png"];
[self download:downloadRequest];

return self;
}
- (BFTask *)download:(AWSS3TransferManagerDownloadRequest *)downloadRequest {
NSLog(@"Download request: %@", downloadRequest);
AWSS3TransferManager *transferManager = [AWSS3TransferManager defaultS3TransferManager];
NSLog(@"%@", [transferManager download:downloadRequest]);
return nil;
}

---

首先，您误用了

AWSS3TransferManagerDownloadRequest

的

downloadingFileURL

属性

downloadingFileURL

不应该指向您正在获取的S3位置；相反，它应该是指将文件写入的磁盘位置，例如：

一旦该文件完成下载，它将显示在该文件路径上

不过，为了知道文件何时准备就绪，我建议在如下块中执行下载请求：

[[transferManager download:downloadRequest]continueWithExecutor
    [BFExecutor mainThreadExecutor] withBlock:^id(BFTask *task) {
    if (task.result) {
        AWSS3TransferManagerDownloadOutput *downloadOutput = task.result;
        self.fetchedImage = [UIImage imageWithContentsOfFile:downloadingFilePath];
    } else if (task.error) {
        NSLog(@"Error: %@", task.error);
    }
}];

---

您在代码中的何处检查下载的文件？

[[transferManager download:downloadRequest]continueWithExecutor
    [BFExecutor mainThreadExecutor] withBlock:^id(BFTask *task) {
    if (task.result) {
        AWSS3TransferManagerDownloadOutput *downloadOutput = task.result;
        self.fetchedImage = [UIImage imageWithContentsOfFile:downloadingFilePath];
    } else if (task.error) {
        NSLog(@"Error: %@", task.error);
    }
}];