How can I use the number of matches with a NSDataDetector for better recognition of a URL?

Question

I'm using a function that fixes URLs that can't be loaded directly into a WKWebView.

I rely on the NSDataDetector for checking whether the URL is valid or not.

NSError *error = NULL;

NSDataDetector *detector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink error:&error];

NSUInteger numberOfMatches = [detector numberOfMatchesInString:URLString options:0 range:NSMakeRange(0, URLString.length)];

if (!error && numberOfMatches > 0) {

    // Valid URL
}
else {

    // Invalid URL

    // Custom code runs here to fix it...
}

Here's the example where it doesn't work:

"/d.scdn.com/images/photo.jpg" ---> "http://stockimages.com/d.scdn.com/images/photo.jpg"

This is how the conversion should be done but instead it recognizes

"/d.scdn.com/images/photo.jpg"

As a valid URL and the fix code doesn't execute.

As you can see the problem with the example above is that a domain name is nested inside the string which I want to fix fooling the NSDataDetector for an actual URL.

Is there a way to take advantage of the numberOfMatches to solve this problem? Is there something like a minimum number of matches for a URL to be valid in relationship with the original string?