我有一个应用程序，目前正在将图像上传到亚马逊S3。我一直在尝试将其从使用NSURLConnection切换到NSURLSession，以便在应用程序在后台时可以继续上传！但我似乎遇到了些问题。虽然创建了NSURLRequest并将其传递给NSURLSession，但是如果我将同样的请求传递给NSURLConnection，亚马逊会返回403 - 禁止响应，并且无法上传该文件。
这是创建响应的代码：
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];
然后这个标志着响应的结束（我想这是来自另一个SO答案）：
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"];
那么如果我使用这行代码：
[NSURLConnection connectionWithRequest:request delegate:self];
它能够正常工作并上传文件，但如果我使用：
NSURLSessionUploadTask *task = [self.session uploadTaskWithRequest:request fromFile:[NSURL fileURLWithPath:filePath]];
[task resume];
我收到了“禁止访问”错误..！？
有没有人试过使用这个方法上传到S3并遇到类似的问题？我想知道这是否与会话暂停和恢复上传的方式有关，或者它对请求做出了一些奇怪的操作..？
一个可能的解决方案是将文件上传到我控制的临时服务器，等待上传完成后再将其转发到S3...但这显然不是理想的解决方案！
非常感谢任何帮助！
谢谢！