NSURLSession UploadTask suspend is not working

Question

I am trying to upload a file and while doing so when I suspend the upload operation, the method:

- URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:

doesn't excute, which is expected. But still it continues to send the complete file to the server.

I tried uploading ~200MB file, and I suspended the operation around 10%. And when I see the server side, I could see data coming.

Below is the code:

NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *documentsURL =[[fileManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]lastObject];
NSURL *urlPath=[documentsURL URLByAppendingPathComponent:@"video2.mp4"];
NSURLSessionConfiguration *backgroundSessionConfigObject = [NSURLSessionConfiguration  backgroundSessionConfiguration:@"ud" ];
//backgorundSession is NSURLSession
self.backgroundSession =[NSURLSession sessionWithConfiguration:backgroundSessionConfigObject delegate:self delegateQueue:[NSOperationQueue mainQueue]];
NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://localhost:5000/upload/"]];
request1.HTTPMethod=@"POST";

uploadTask=[backgroundSession uploadTaskWithRequest:request fromFile:urlPath];
[uploadTask resume];

I am not able to suspend the task. Though it stops the execution of below method. But it still pushes the data to the server.

- URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:

Network

1.3k

Posted by

utsavdusad

Reply

Add a Comment

Answer 1

NSURLSession’s suspend and resume support is not really designed to implement a user-level ‘pause the transfer’ feature. Rather, it’s there to allow you to temporarily disable callbacks as part of some sort of concurrency control system. That's because, as you’ve noticed, a suspended task can still be active on the wire; all that the suspend does is prevent it from making progress internally, issuing callbacks, and so on.

If you’re implementing a user-level pause feature, my recommendation is as follows:

For downloads, you should call
```
-cancelByProducingResumeData:
```
and then resume with
```
-downloadTaskWithResumeData:
```
. This is supported by most servers.
For uploads, things get much trickier. Does your server explicitly support the ability to stop and resume the upload?

Share and Enjoy
—
Quinn "The Eskimo!"
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Add a Comment

Answer 2

Below is the code:

NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *documentsURL =[[fileManager URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]lastObject];
NSURL *urlPath=[documentsURL URLByAppendingPathComponent:@"video2.mp4"];
NSURLSessionConfiguration *backgroundSessionConfigObject = [NSURLSessionConfiguration  backgroundSessionConfiguration:@"ud" ];
//backgorundSession is NSURLSession
self.backgroundSession =[NSURLSession sessionWithConfiguration:backgroundSessionConfigObject delegate:self delegateQueue:[NSOperationQueue mainQueue]];
NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://localhost:5000/upload/"]];
request1.HTTPMethod=@"POST";

uploadTask=[backgroundSession uploadTaskWithRequest:request fromFile:urlPath];
[uploadTask resume];

I am not able to suspend the task. Though it stops the execution of below method. But it still pushes the data to the server.

- URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:

Posted by

utsavdusad

Add a Comment

Answer 3

NSURLSession’s suspend and resume support is not really designed to implement a user-level ‘pause the transfer’ feature. Rather, it’s there to allow you to temporarily disable callbacks as part of some sort of concurrency control system. That's because, as you’ve noticed, a suspended task can still be active on the wire; all that the suspend does is prevent it from making progress internally, issuing callbacks, and so on.

If you’re implementing a user-level pause feature, my recommendation is as follows:

For downloads, you should call
```
-cancelByProducingResumeData:
```
and then resume with
```
-downloadTaskWithResumeData:
```
. This is supported by most servers.
For uploads, things get much trickier. Does your server explicitly support the ability to stop and resume the upload?

Share and Enjoy
—
Quinn "The Eskimo!"
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Add a Comment

NSURLSession UploadTask suspend is not working

Accepted Reply

Replies