比较两个NSURL或一个NSURL和一个NSString的可靠方法?

I recently had a problem when comparing two NSURLs and compare one NSURL with an NSString(which is a URL address), the situation is I got an NSURLRequest from somewhere, I may or may not know the URL address it points to, and I have an URL NSString, say "https://m.google.com", now I need to check if the URL in that NSURLRequest is the same as the URL string I had:I recently had a problem when comparing two NSU