regex - Balancing Group In Objective-C -

does regular expression in objc support balancing group? if not, there other solution fix it?

i find pattern syntax supported specified icu in apple developer , icu tells nothing balancing group.

a simple test balancing group,

(?'group'1)2(?'-group'3)(?(group)?!) 

i test both in xcode search field , using nsregularexpression.

here code , error:

nserror* error; re = [nsregularexpression regularexpressionwithpattern:@"(?'group'1)2(?'-group'3)(?(group)?!)" options:nsregularexpressioncaseinsensitive error:&error]; nslog(error); 

error:

error domain=nscocoaerrordomain code=2048 "the value “(?'group'1)2(?'-group'3)(?(group)?!)” invalid." userinfo=0x1003b85b0 {nsinvalidvalue=(?'group'1)2(?'-group'3)(?(group)?!)}