totalBytesExpectedToWrite is -1 in NSURLSessionDownloadTask

Question

I faced with a strange problem. I load file from the Internet using NSURLSession and NSURLSessionDownloadTask. Here is the code

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Answer 1

The web service may not be providing the total size in the header field Content-Length.

If the total size is not provided there is no way for your app to know the length and this provide a progress bar.

Check what is coming from the web server with a analyzer such as Charles Proxy.