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iosswiftalamofire

Alamofire does not set `If-None-Match` header automatically

I have an iOS app that making API calls to 2 different servers (server A and server B) using Alamofire 5.2.2. Based on my understanding and what I read on StackOverflow, Alamofire should automatically set the If-None-Match request header as long as the cache policy is set to .useProtocolCachePolicy, and return status code 200 to the app if the server responded with status code 304.

I am able to make an API call to server A and Alamofire is setting the If-None-Match header as expected. However, by using the same set of code, Alamofire is not setting the If-None-Match header when I make API call to server B.

One thing I notice is that server A is using a strong validation:

Etag: "7266bc2f1b245365bb1a74da5185bca6"

Whereas, server B is using a weak validation:

ETag: W/"6672-pKPf8kg1eUMH8msoW0et1yskcQQ"

I also tried to manually set the If-None-Match header when calling server B and the server responded with status code 304. I was expecting Alamofire to return status code 200 to my app, instead, it returns status code 304.

Any idea why Alamofire does not automatically set the If-None-Match when making API call to server B? Is that an Alamofire bug or just a server config issue? Anything I can do to get the same behavior as making API call to server A?

Thanks in advance.

Solution

  • Apparently, the reason for my problem is because server B has the response header Cache-Control = no-store and Alamofire is respecting this header and ignore the given Etag.