NSURLSession cancelByProducingResumeData vs. 302 redirects

Question

jackpal OP

Created Aug ’15

Replies 3

Boosts 0

Participants 2

The documentation for NSURLSession cancelByProducingResumeData states:

A download can be resumed only if the following conditions are met:

The resource has not changed since you first requested it
The task is an HTTP or HTTPS GET request
The server provides either the ETag or Last-Modified header (or both) in its response
The server supports byte-range requests
The temporary file hasn’t been deleted by the system in response to disk space pressure

What if the original URL request responds with a 302 (temporary redirect)?

In my testing, it seems that if my server responds a 302 (temporary redirect), then NSURLSession cancelByProducingResumeData does not produce resume data.

Is this the expected behavior?

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Answer 1

DTS Engineer OP

Apple

Aug ’15

In my testing, it seems that if my server responds a 302 (temporary redirect), then NSURLSession cancelByProducingResumeData does not produce resume data.

Does this happen in a background session, a standard session, or both?

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

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

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Answer 2

jackpal OP

Aug ’15

I am only using background sessions. The problem seems to reproduce in iOS 8.2. (Tested in an iPhone 4s simulator.)

The good news (for me) is that I just noticed that I _am_ receiving resume data for 302 redirects on iOS 9.0 b4 on both simulator and a real iPhone 6 device.

So perhaps it's a limitation of older versions of iOS that's fixed in more recent versions of iOS.

0

Answer 3

DTS Engineer OP

Apple

Aug ’15

So perhaps it's a limitation of older versions of iOS that's fixed in more recent versions of iOS.

Sounds likely.

You may be able to work around this on pre-iOS 9 systems by issuing the initial request in a standard session, stopping that request once you get the redirect, and then issuing the redirected request in your background session. This will work as long as the server that issues the redirect doesn't have some sort of timeout on the redirect.

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

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

0