Open Radar

 
Summary:
It would be truly wonderful if we could set a global custom user-agent string that was used by NSURLConnection unless explicitly overridden in a custom NSURLRequest. Basically, this global value would be set to the request header whenever an NSURLRequest was created, allowing it to be one-off customized by the caller immediately afterwards as needed.

It might make sense to expose a global key-value request header store rather than solving the problem just for the user-agent. Setting to nil on a global or per-instance basis could restore the Apple default behavior, while setting to the empty string could deliberately submit a clear value.

Right now, developers must centralize all their NSURLRequest creation so that it contains a custom user-agent. Worse, though, is that there's little that can be done with third-party web service libraries in an app that can't be reached. In many cases, a solution like the one proposed here is the only option.

So the idea is:

[NSURLRequest setValue:@"MyApp v1.2 iOS" forHTTPHeaderField:@"User-Agent"]; // Class method; all NSURLRequests will now use this field value by default.

// ...

NSURLRequest *requestOne = [NSURLRequest requestWithURL:myURL]; // Preconfigured with the above UA

NSMutableURLRequest *customRequest = [NSMutableURLRequest requestWithURL:myURL]; // Also preconfigured

[customRequest setValue:@"AnotherUserAgent" forHTTPHeaderField:@"User-Agent"]; // Overrides global UA

[customRequest setValue:nil forHTTPHeaderField:@"User-Agent"]; // Falls back to the Apple default

Ideally, this would also affect requests by the Apple frameworks — AVPlayer and MPMoviePlayerController, for instance — but I'll log a separate bug for those just in case.