我想将大量文件(~50MB)上传到服务器,并且请求必须要流式传输. (否则app会因内存压力而崩溃)
我已尝试过各种方法在AFNetworking 2.0中做到这一点而没有任何成功.
这就是我目前正在做的事情：
NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:baseServiceUrl parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
int imageIndex = 0;
for (NSURL *tempFileUrl in tempFilesUrlList) {
NSString* fileName = [NSString stringWithFormat:@"image%d",imageIndex];
NSError *appendError = nil;
[formData appendPartWithFileURL:tempFileUrl name:fileName error:&appendError];
imageIndex++;
}
} error:&error];
AFHTTPRequestOperation *requestOperation = nil;
requestOperation = [manager HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation,id responSEObject) {
DLog(@"Uploading files completed: %@\n %@",operation,responSEObject);
} failure:^(AFHTTPRequestOperation *operation,NSError *error) {
DLog(@"Error: %@",error);
}];
[requestOperation setUploadProgressBlock:^(NSUInteger bytesWritten,long long totalBytesWritten,long long totalBytesExpectedToWrite) {
double percentDone = (double)totalBytesWritten / (double)totalBytesExpectedToWrite;
DLog(@"progress updated(percentDone) : %f",percentDone);
}];
[requestOperation start];
这工作正常,但它不流.如果请求太大,它准备内存中的请求可能会崩溃.我曾尝试使用原生套接字和流,但Apple表示他们可能因此而拒绝该应用.
我尝试过的另一种方法是：
AFHTTPSessionManager* manager = [AFHTTPSessionManager manager];
NSString *appID = [[NSBundle mainBundle] bundleIdentifier];
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration backgroundSessionConfiguration:appID];
NSURL* serviceUrl = [NSURL URLWithString:baseServiceUrl];
manager = [manager initWithBaseURL:serviceUrl sessionConfiguration:configuration];
NSURLSessionDataTask *uploadFilesTask = [manager POST:baseServiceUrl parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
int imageIndex = 0;
for (NSURL *tempFileUrl in tempFilesUrlList) {
NSString* fileName = [NSString stringWithFormat:@"image%d",imageIndex];
NSError *appendError = nil;
[formData appendPartWithFileURL:tempFileUrl name:fileName error:&appendError];
imageIndex++;
}
} success:^(NSURLSessionDataTask *task,id responSEObject) {
DLog(@"Files uploaded successfully: %@\n %@",task,responSEObject);
} failure:^(NSURLSessionDataTask *task,error);
}];
[progressBar setProgressWithUploadProgressOfTask:uploadFilesTask animated:true];
但这给了我运行时错误说：
Terminating app due to uncaught exception ‘NSGenericException’,
reason: ‘Upload tasks in background sessions must be from a file’
*** First throw call stack: ( 0 CoreFoundation 0x02cc75e4 __exceptionPreprocess + 180 1 libobjc.A.dylib
0x02a4a8b6 objc_exception_throw + 44 2 CFNetwork
0x0459eb6c -[__NSCFBackgroundSessionBridge
uploadTaskForRequest:uploadFile:bodyData:completion:] + 994 3
CFNetwork 0x045f2f37 -[__NSCFURLSession
uploadTaskWithStreamedRequest:] + 73
(必须是流媒体,并且能够在后台继续)
解决方法
我建议使用AFNetworking等网络库.它将使您免于执行之前已解决的单调任务.
为了在后台真正发送请求,您需要将整个请求写入文件,然后使用NSURLSession将其传输到服务器. (这是接受的答案 – 下面的链接)因此,您需要将请求写入磁盘而不将整个文件读入内存.
How to upload task in background using afnetworking
NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:@"http://example.com/upload" parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
[formData appendPartWithFileURL:[NSURL fileURLWithPath:@"file://path/to/image.jpg"] name:@"file" fileName:@"filename.jpg" mimeType:@"image/jpeg" error:nil];
} error:nil];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
NSProgress *progress = nil;
NSURLSessionUploadTask *uploadTask = [manager uploadTaskWithStreamedRequest:request progress:&progress completionHandler:^(NSURLResponse *response,id responSEObject,NSError *error) {
if (error) {
NSLog(@"Error: %@",error);
} else {
NSLog(@"%@ %@",response,responSEObject);
}
enter code here
}];
[uploadTask resume];
http://cocoadocs.org/docsets/AFNetworking/2.5.0/
注意：一个简单的解决方案是请求您的应用在后台运行的时间.当你的app delegate上调用applicationDidEnterBackground：时,你可以调用[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler：]来请求一些时间在后台运行. ([[UIApplication sharedApplication] endBackgroundTask：];说你已经完成了.)你问的有什么缺点？您将获得有限的时间. “如果你没有在时间到期之前调用endBackgroundTask：对于每个任务,系统会杀死应用程序.如果你在handler参数中提供一个块对象,系统会在时间到期之前调用你的处理程序,让你有机会结束任务. “
进展
您可以使用子/父关系跟踪多个NSProgress对象的进度.您可以创建一个NSProgress * overallProgress对象,然后调用[overallProgress becomeCurrentWithPendingUnitCount：< unit size>];在创建新请求和[overallProgress resignCurrent]之前;然后.您的overallProgress对象将反映所有孩子的进度.
