Extracting a URL from within a string

Question

My app receives numerous text strings which may or may not contain a URL anywhere within the string. What would be the best method to extract a URL from within a string? Thank you.

zonble · Accepted Answer · 2010-03-15 03:16:18Z

8

If you are working on a Mac application, Mac OS X 10.6 offers a new API to let you detect URLs with the spell checker. You may do it this way.

NSString *s = @"http://example.com"
NSInteger wordCount = 0;
NSOrthography *orthography = nil;
NSArray *checkResults = [[NSSpellChecker sharedSpellChecker] checkString:s range:NSMakeRange(0, [s length]) types:NSTextCheckingTypeLink options:nil inSpellDocumentWithTag:0 orthography:&orthography wordCount:&wordCount];
for (NSTextCheckingResult *result in checkResults) {
    NSRange range = result.range;
    NSURL *URL = result.URL;
}

answered Mar 15, 2010 at 3:16

zonble

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2 Comments

Mike Abdullah Over a year ago

This is definitely preferable to bringing in a dedicated framework if you can. Note that you don't actually care about word count of orthography usually when searching for links, so just pass in a NULL pointer for efficiency.

Mike Abdullah Over a year ago

I've also implemented this in our open source KSFileUtilities code: github.com/karelia/KSFileUtilities/commit/…

Peter Hosey · Accepted Answer · 2010-03-14 21:35:19Z

3

The BSD-licensed AutoHyperlinks framework provides classes to scan text for URLs and either return them to you or mark them up as links in an attributed string.

I don't think it builds out of the box for the iPhone, but you could always add preprocessor directives to cut out any AppKit-dependent code. The scan-and-return interface should just work, once you get it to build. (Make sure to run the tests.)

Mike Abdullah wrote a patch for iPhone support. You might try that.

edited Mar 14, 2010 at 21:35

answered Mar 14, 2010 at 20:39

Peter Hosey

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3 Comments

RunLoop Over a year ago

Thanks, I tried this but judging by the number of errors and warnings generated, it will require a significant amount work to get this working on the iPhone -

Peter Hosey Over a year ago

JK: That can be misleading. A single line of code can produce a lot of errors if it's sufficiently uncompilable, but it's still only one line of code. I think the AppKit-dependent parts of AutoHyperlinks are isolated enough that you could conditionalize them out fairly easily.

RunLoop Over a year ago

Thanks Peter. I'll give the patch a try tomorrow.

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