我有一个应用程序，目前正在将图像上传到亚马逊S3。我一直在尝试将它从使用NSURLConnection切换到NSURLSession，以便在应用程序处于后台时上传可以继续！我似乎遇到了一些问题。创建NSURLRequest并将其传递给NSURLSession，但亚马逊发回403禁止响应，如果我将相同的请求传递给NSURLConnection，则它会完美地上传文件。
以下是创建响应的代码：
NSString *requestURLString = [NSString stringWithFormat:@"http://%@.%@/%@/%@", BUCKET_NAME, AWS_HOST, DIRECTORY_NAME, filename];
NSURL *requestURL = [NSURL URLWithString:requestURLString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:requestURL
cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData
timeoutInterval:60.0];
// Configure request
[request setHTTPMethod:@"PUT"];
[request setValue:[NSString stringWithFormat:@"%@.%@", BUCKET_NAME, AWS_HOST] forHTTPHeaderField:@"Host"];
[request setValue:[self formattedDateString] forHTTPHeaderField:@"Date"];
[request setValue:@"public-read" forHTTPHeaderField:@"x-amz-acl"];
[request setHTTPBody:imageData];
然后这标志着回应（我认为这来自另一个SO回答）：
NSString *contentMd5 = [request valueForHTTPHeaderField:@"Content-MD5"];
NSString *contentType = [request valueForHTTPHeaderField:@"Content-Type"];
NSString *timestamp = [request valueForHTTPHeaderField:@"Date"];
if (nil == contentMd5) contentMd5 = @"";
if (nil == contentType) contentType = @"";
NSMutableString *canonicalizedAmzHeaders = [NSMutableString string];
NSArray *sortedHeaders = [[[request allHTTPHeaderFields] allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
for (id key in sortedHeaders)
{
NSString *keyName = [(NSString *)key lowercaseString];
if ([keyName hasPrefix:@"x-amz-"]){
[canonicalizedAmzHeaders appendFormat:@"%@:%@\n", keyName, [request valueForHTTPHeaderField:(NSString *)key]];
}
}
NSString *bucket = @"";
NSString *path = request.URL.path;
NSString *query = request.URL.query;
NSString *host = [request valueForHTTPHeaderField:@"Host"];
if (![host isEqualToString:@"s3.amazonaws.com"]) {
bucket = [host substringToIndex:[host rangeOfString:@".s3.amazonaws.com"].location];
}
NSString* canonicalizedResource;
if (nil == path || path.length < 1) {
if ( nil == bucket || bucket.length < 1 ) {
canonicalizedResource = @"/";
}
else {
canonicalizedResource = [NSString stringWithFormat:@"/%@/", bucket];
}
}
else {
canonicalizedResource = [NSString stringWithFormat:@"/%@%@", bucket, path];
}
if (query != nil && [query length] > 0) {
canonicalizedResource = [canonicalizedResource stringByAppendingFormat:@"?%@", query];
}
NSString* stringToSign = [NSString stringWithFormat:@"%@\n%@\n%@\n%@\n%@%@", [request HTTPMethod], contentMd5, contentType, timestamp, canonicalizedAmzHeaders, canonicalizedResource];
NSString *signature = [self signatureForString:stringToSign];
[request setValue:[NSString stringWithFormat:@"AWS %@:%@", self.S3AccessKey, signature] forHTTPHeaderField:@"Authorization"];
然后，如果我使用这行代码：
[NSURLConnection connectionWithRequest:request delegate:self];
它工作并上传文件，但如果我使用：
NSURLSessionUploadTask *task = [self.session uploadTaskWithRequest:request fromFile:[NSURL fileURLWithPath:filePath]];
[task resume];
我得到了禁止的错误..！？
有没有人尝试使用此功能上传到S3并遇到类似问题？我想知道是否与会话暂停和恢复上传的方式有关，或者它是否对请求做了一些有趣的事情。？
一种可能的解决方案是将文件上传到我控制的临时服务器，并在完成后将其转发到S3 ......但这显然不是理想的解决方案！
非常感谢任何帮助!!
谢谢！
答案 0 :(得分：8)
我根据Zeev Vax回答了它。我想对遇到的问题提供一些见解，并提供一些小的改进。
建立一个普通的PutRequest，例如
S3PutObjectRequest* putRequest = [[S3PutObjectRequest alloc] initWithKey:keyName inBucket:bucketName];
putRequest.credentials = credentials;
putRequest.filename = theFilePath;
现在我们需要做一些S3Client通常为我们做的工作
// set the endpoint, so it is not null
putRequest.endpoint = s3Client.endpoint;
// if you are using session based authentication, otherwise leave it out
putRequest.securityToken = messageTokenDTO.securityToken;
// sign the request (also computes md5 checksums etc.)
NSMutableURLRequest *request = [s3Client signS3Request:putRequest];
现在将所有这些复制到新请求中。亚马逊使用自己的NSUrlRequest类，这会导致异常
NSMutableURLRequest* request2 = [[NSMutableURLRequest alloc]initWithURL:request.URL];
[request2 setHTTPMethod:request.HTTPMethod];
[request2 setAllHTTPHeaderFields:[request allHTTPHeaderFields]];
现在我们可以开始实际转移了
NSURLSession* backgroundSession = [self backgroundSession];
_uploadTask = [backgroundSession uploadTaskWithRequest:request2 fromFile:[NSURL fileURLWithPath:theFilePath]];
[_uploadTask resume];
这是创建后台会话的代码：
- (NSURLSession *)backgroundSession {
static NSURLSession *session = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfiguration:@"com.example.my.unique.id"];
session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
});
return session;
}
我花了一段时间才弄清楚会话/任务委托需要处理auth挑战（我们实际上是对s3的身份验证）。所以只需实施
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler {
NSLog(@"session did receive challenge");
completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
}
答案 1 :(得分：5)
这里的答案有点过时，我花了很多时间试图在Swift和新的AWS SDK中完成这项工作。所以这里是如何使用新的AWSS3PreSignedURLBuilder（版本2.0.7 +中）在Swift中完成的：
class S3BackgroundUpload : NSObject {
// Swift doesn't support static properties yet, so have to use structs to achieve the same thing.
struct Static {
static var session : NSURLSession?
}
override init() {
super.init()
// Note: There are probably safer ways to store the AWS credentials.
let configPath = NSBundle.mainBundle().pathForResource("appconfig", ofType: "plist")
let config = NSDictionary(contentsOfFile: configPath!)
let accessKey = config.objectForKey("awsAccessKeyId") as String?
let secretKey = config.objectForKey("awsSecretAccessKey") as String?
let credentialsProvider = AWSStaticCredentialsProvider .credentialsWithAccessKey(accessKey!, secretKey: secretKey!)
// AWSRegionType.USEast1 is the default S3 endpoint (use it if you don't need specific endpoints such as s3-us-west-2.amazonaws.com)
let configuration = AWSServiceConfiguration(region: AWSRegionType.USEast1, credentialsProvider: credentialsProvider)
// This is setting the configuration for all AWS services, you can also pass in this configuration to the AWSS3PreSignedURLBuilder directly.
AWSServiceManager.defaultServiceManager().setDefaultServiceConfiguration(configuration)
if Static.session == nil {
let configIdentifier = "com.example.s3-background-upload"
var config : NSURLSessionConfiguration
if NSURLSessionConfiguration.respondsToSelector("backgroundSessionConfigurationWithIdentifier:") {
// iOS8
config = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(configIdentifier)
} else {
// iOS7
config = NSURLSessionConfiguration.backgroundSessionConfiguration(configIdentifier)
}
// NSURLSession background sessions *need* to have a delegate.
Static.session = NSURLSession(configuration: config, delegate: self, delegateQueue: nil)
}
}
func upload() {
let s3path = "/some/path/some_file.jpg"
let filePath = "/var/etc/etc/some_file.jpg"
// Check if the file actually exists to prevent weird uncaught obj-c exceptions.
if NSFileManager.defaultManager().fileExistsAtPath(filePath) == false {
NSLog("file does not exist at %@", filePath)
return
}
// NSURLSession needs the filepath in a "file://" NSURL format.
let fileUrl = NSURL(string: "file://\(filePath)")
let preSignedReq = AWSS3GetPreSignedURLRequest()
preSignedReq.bucket = "bucket-name"
preSignedReq.key = s3path
preSignedReq.HTTPMethod = AWSHTTPMethod.PUT // required
preSignedReq.contentType = "image/jpeg" // required
preSignedReq.expires = NSDate(timeIntervalSinceNow: 60*60) // required
// The defaultS3PreSignedURLBuilder uses the global config, as specified in the init method.
let urlBuilder = AWSS3PreSignedURLBuilder.defaultS3PreSignedURLBuilder()
// The new AWS SDK uses BFTasks to chain requests together:
urlBuilder.getPreSignedURL(preSignedReq).continueWithBlock { (task) -> AnyObject! in
if task.error != nil {
NSLog("getPreSignedURL error: %@", task.error)
return nil
}
var preSignedUrl = task.result as NSURL
NSLog("preSignedUrl: %@", preSignedUrl)
var request = NSMutableURLRequest(URL: preSignedUrl)
request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
// Make sure the content-type and http method are the same as in preSignedReq
request.HTTPMethod = "PUT"
request.setValue(preSignedReq.contentType, forHTTPHeaderField: "Content-Type")
// NSURLSession background session does *not* support completionHandler, so don't set it.
let uploadTask = Static.session?.uploadTaskWithRequest(request, fromFile: fileUrl)
// Start the upload task:
uploadTask?.resume()
return nil
}
}
}
extension S3BackgroundUpload : NSURLSessionDelegate {
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
NSLog("did receive data: %@", NSString(data: data, encoding: NSUTF8StringEncoding))
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
NSLog("session did complete")
if error != nil {
NSLog("error: %@", error!.localizedDescription)
}
// Finish up your post-upload tasks.
}
}
答案 2 :(得分：3)
我还不太了解NSURLSessionUploadTask，但我可以告诉你如何调试它。
我会使用像Charles这样的工具来查看我的应用程序发出的HTTP（S）请求。问题可能是NSURLSessionUploadTask忽略了您设置的标头，或者它使用的方法与Amazon的S3期望的文件上载不同。这可以通过拦截代理轻松验证。
此外，当Amazon S3返回403之类的错误时，它实际上会发回一个XML文档，其中包含有关错误的更多信息。也许有NSURLSession的委托方法可以检索响应正文？如果没有，那么查尔斯肯定会给你更多的见解。
答案 3 :(得分：2)
这是我运行任务的代码：
AmazonS3Client *s3Client = [[AmazonS3Client alloc] initWithAccessKey:accessKey withSecretKey:secretKey];
S3PutObjectRequest *s3PutObjectRequest = [[S3PutObjectRequest alloc] initWithKey:[url lastPathComponent] inBucket:bucket];
s3PutObjectRequest.cannedACL = [S3CannedACL publicRead];
s3PutObjectRequest.endpoint = s3Client.endpoint;
s3PutObjectRequest.contentType = fileMIMEType([url absoluteString]);
[s3PutObjectRequest configureURLRequest];
NSMutableURLRequest *request = [s3Client signS3Request:s3PutObjectRequest];
NSMutableURLRequest *request2 = [[NSMutableURLRequest alloc]initWithURL:request.URL];
[request2 setHTTPMethod:request.HTTPMethod];
[request2 setAllHTTPHeaderFields:[request allHTTPHeaderFields]];
NSURLSessionUploadTask *task = [[self backgroundURLSession] uploadTaskWithRequest:request2 fromFile:url];
[task resume];
我开源上传了我的S3后台https://github.com/genadyo/S3Uploader/
答案 4 :(得分：2)
对于后台上传/下载，您需要使用NSURLSession和后台配置。 从AWS SDK 2.0.7开始，您可以使用预先签名的请求：
PreSigned URL Builder ** - SDK现在包含对预签名的支持 亚马逊简单存储服务（S3）URL。您可以使用这些URL 使用NSURLSession类执行后台传输。
初始化后台NSURLSession和AWS服务
- (void)initBackgroundURLSessionAndAWS
{
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:AWSS3BackgroundSessionUploadIdentifier];
self.urlSession = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
AWSServiceConfiguration *configuration = [AWSServiceConfiguration configurationWithRegion:DefaultServiceRegionType credentialsProvider:credentialsProvider];
[AWSServiceManager defaultServiceManager].defaultServiceConfiguration = configuration;
self.awss3 = [[AWSS3 alloc] initWithConfiguration:configuration];
}
实施上传文件功能
- (void)uploadFile
{
AWSS3GetPreSignedURLRequest *getPreSignedURLRequest = [AWSS3GetPreSignedURLRequest new];
getPreSignedURLRequest.bucket = @"your_bucket";
getPreSignedURLRequest.key = @"your_key";
getPreSignedURLRequest.HTTPMethod = AWSHTTPMethodPUT;
getPreSignedURLRequest.expires = [NSDate dateWithTimeIntervalSinceNow:3600];
//Important: must set contentType for PUT request
getPreSignedURLRequest.contentType = @"your_contentType";
[[[AWSS3PreSignedURLBuilder defaultS3PreSignedURLBuilder] getPreSignedURL:getPreSignedURLRequest] continueWithBlock:^id(BFTask *task) {
if (task.error)
{
NSLog(@"Error BFTask: %@", task.error);
}
else
{
NSURL *presignedURL = task.result;
NSLog(@"upload presignedURL is: \n%@", presignedURL);
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:presignedURL];
request.cachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
[request setHTTPMethod:@"PUT"];
[request setValue:contentType forHTTPHeaderField:@"Content-Type"];
// Background NSURLSessions do not support the block interfaces, delegate only.
NSURLSessionUploadTask *uploadTask = [self.session uploadTaskWithRequest:request fromFile:@"file_path"];
[uploadTask resume];
}
return nil;
}];
}
NSURLSession委托功能：
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
if (error)
{
NSLog(@"S3 UploadTask: %@ completed with error: %@", task, [error localizedDescription]);
}
else
{
// AWSS3GetPreSignedURLRequest does not contain ACL property, so it has to be set after file was uploaded
AWSS3PutObjectAclRequest *aclRequest = [AWSS3PutObjectAclRequest new];
aclRequest.bucket = @"your_bucket";
aclRequest.key = @"yout_key";
aclRequest.ACL = AWSS3ObjectCannedACLPublicRead;
[[self.awss3 putObjectAcl:aclRequest] continueWithBlock:^id(BFTask *bftask) {
dispatch_async(dispatch_get_main_queue(), ^{
if (bftask.error)
{
NSLog(@"Error putObjectAcl: %@", [bftask.error localizedDescription]);
}
else
{
NSLog(@"ACL for an uploaded file was changed successfully!");
}
});
return nil;
}];
}
}
答案 5 :(得分：0)
最近亚马逊已将AWS api更新为2.2.4。 此更新的特点是，它支持后台上传，您不必使用NSURLSession上传视频非常简单，您可以使用以下源块来测试它，我已经测试过使用我的旧版本，它比以前的版本快30-40％
在AppDelegate.m中的didFinishLaunchingWithOptions方法 //〜GM~为AWS V2配置设置cognito
AWSStaticCredentialsProvider *staticProvider = [[AWSStaticCredentialsProvider alloc] initWithAccessKey:@"xxxx secretKey:@"xxxx"];
AWSServiceConfiguration *configuration = [[AWSServiceConfiguration alloc] initWithRegion:AWSRegionUSWest2 credentialsProvider:staticProvider];
AWSServiceManager.defaultServiceManager.defaultServiceConfiguration = configuration;
[AWSS3TransferUtility interceptApplication:application
handleEventsForBackgroundURLSession:identifier
completionHandler:completionHandler];
在上传课程
NSURL *fileURL = // The file to upload.
AWSS3TransferUtilityUploadExpression *expression = [AWSS3TransferUtilityUploadExpression new];
expression.uploadProgress = ^(AWSS3TransferUtilityTask *task, int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend) {
dispatch_async(dispatch_get_main_queue(), ^{
// Do something e.g. Update a progress bar.
});
};
AWSS3TransferUtilityUploadCompletionHandlerBlock completionHandler = ^(AWSS3TransferUtilityUploadTask *task, NSError *error) {
dispatch_async(dispatch_get_main_queue(), ^{
// Do something e.g. Alert a user for transfer completion.
// On failed uploads, `error` contains the error object.
});
};
AWSS3TransferUtility *transferUtility = [AWSS3TransferUtility defaultS3TransferUtility];
[[transferUtility uploadFile:fileURL
bucket:@"YourBucketName"
key:@"YourObjectKeyName"
contentType:@"text/plain"
expression:expression
completionHander:completionHandler] continueWithBlock:^id(AWSTask *task) {
if (task.error) {
NSLog(@"Error: %@", task.error);
}
if (task.exception) {
NSLog(@"Exception: %@", task.exception);
}
if (task.result) {
AWSS3TransferUtilityUploadTask *uploadTask = task.result;
// Do something with uploadTask.
}
return nil;
}];
更多参考资料：https://aws.amazon.com/blogs/mobile/amazon-s3-transfer-utility-for-ios/