How to get matches in iOS using regular expression?

Question

I got a string like \'stackoverflow.html\' and in the regular expression \'stack(.).html\' I would like to have the value in (.).

I could only find NSPredic

Answer 1

You want the RegexKitLite library in order to perform regular expression matches:

http://regexkit.sourceforge.net/RegexKitLite/

After that it's almost exactly like you do it in PHP.

I'll add some code to help you with it:

NSString *string     = @"stackoverflow.html";
NSString *expression = @"stack(.*)\\.html";
NSString *matchedString = [string stringByMatching:expression capture:1];

matchedString is @"overflow", which should be exactly what you need.

Answer 2

in iOS 4.0+, you can use NSRegularExpression:

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"stack(.*).html" options:0 error:NULL];
NSString *str = @"stackoverflow.html";
NSTextCheckingResult *match = [regex firstMatchInString:str options:0 range:NSMakeRange(0, [str length])];
// [match rangeAtIndex:1] gives the range of the group in parentheses
// [str substringWithRange:[match rangeAtIndex:1]] gives the first captured group in this example