How to determine if a string is a URL in Objective-C

Question

I'm new to iPhone development and Objective-C. Using the ZBar SDK I've developed a basic app which scans a QR image from the photo album and outputs what it translates to.

I want to know if there is a way to take this output, determine whether it is a URL and if so open it in a web browser.

Answer 1

NSURL's URLWithString returns nil if the URL passed is not valid. So, you can just check the return value to determine if the URL is valid.

UPDATE

Just using URLWithString: will usually not be enough, you probably also want to check if the url has a scheme and a host, otherwise, urls such as al:/dsfhkgdsk will pass the test.

So you probably want to do something like this:

NSURL *url = [NSURL URLWithString:yourUrlString];
if (url && url.scheme && url.host)
{
   //the url looks ok, do something with it
   NSLog(@"%@ is a valid URL", yourUrlString);
}

If you only want to accept http URLs you may want to add [url.scheme isEqualToString:@"http"].

Answer 2

Here is an alternative solution which I came across. You can do like this.

NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"yourstring"]];
bool valid = [NSURLConnection canHandleRequest:req];

Source : https://stackoverflow.com/a/13650542/2513947