Question

Is there a reliable way to detect iPhone 4 (as opposed to iPhone 3 or iPad)? extra points if you can do it with .browser files or WURFL

Answer 1

Checkout 51degress.mobi on codeplex. It is active and I have had good experience with it in past.

There is another codeplex project too but its no longer active: Mobile Device Browser File

To detect iPhone 4 specifically, use:

string strUserAgent = Request.UserAgent.ToString().ToLower();
if (Request.Browser.IsMobileDevice == true && strUserAgent.Contains("iphone OS 4")) 
{
    // code for iPhone 4
}

iPhone user agents look like (n stands for version like 4_3_3)

Mozilla/5.0 (iPhone; U; CPU iPhone OS
4_n_n like Mac OS X; en-us)
AppleWebKit/532.9 (KHTML, like Gecko)
Version/4.0.5 Mobile/8A293
Safari/6531.22.7