CODEWITHSUNDEEP
iosobjective-cregex
seguedestination
seguedestination

Reputation: 419

How can I know which part of regex is matched of Objective-c

I have declare a NSRegularExpression. For example like [0-9]{1,4}|abc|ABC . And I input a NSString: @"123". If I check the NSTextCheckingResult, it is not nil. So I know the string match the Regex. However, can I know more about which part is matched? For this scenario, I know Regex [0-9]{1,4} is matched. How can I do this? Thanks!

Upvotes: 0

Views: 129

Answers (2)

Martin R
Martin R

Reputation: 539685

If I understand your question correctly, you have to use capture groups (...):

NSString *pattern = @"([0-9]{1,4})|(abc)|(ABC)";

If the string matches the first capture group in the pattern then 

[result rangeAtIndex:1]

will be the range of matching substring, while

[result rangeAtIndex:2]
[result rangeAtIndex:3]

have range.location == NSNotFound. Example:

NSString *pattern = @"([0-9]{1,4})|(abc)|(ABC)";
NSRegularExpression *regex = [[NSRegularExpression alloc] initWithPattern:pattern options:0 error:nil];

NSString *str = @"123";
NSTextCheckingResult *result = [regex firstMatchInString:str options:0 range:NSMakeRange(0, str.length)];

NSLog(@"%@", NSStringFromRange([result rangeAtIndex:1])); // {0, 3}
NSLog(@"%@", NSStringFromRange([result rangeAtIndex:2])); // {9223372036854775807, 0}
NSLog(@"%@", NSStringFromRange([result rangeAtIndex:3])); // {9223372036854775807, 0}

Upvotes: 2

vadian
vadian

Reputation: 285069

Press ⇧⌘0 and type NSTextCheckingResult or ⌥-click on the symbol to get the class definition.

There are properties range, resultType, numberOfRanges and many more.

Or call rangeOfFirstMatchInString:options:range on the NSRegularExpression instance to get the range directly.

Upvotes: 0

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