IOS marks all characters in a string of characters

    nsmutablestring * Mutstr = [nsmutablestring stringwithstring:@ "AAABBBBAAACCC"];    NSString * str = @ "a";    Nsrange range = {0,mutstr.length};    [Mutstr replaceoccurrencesofstring:@ "" withstring:@ "" Options:nsliteralsearch Range:range];        [Mutstr replaceoccurrencesofstring:@ "\ n" withstring:@ "" Options:nsliteralsearch Range:range];    nsmutableattributedstring * attr = [[nsmutableattributedstring alloc]initwithstring:mutstr];    Nserror * ERROR; Nsregularexpression * Express = [nsregularexpression regularexpressionwithpattern:str options:    Nsregularexpressioncaseinsensitive error:&error];    Nsarray<nstextcheckingresult *> * result = [Express matchesinstring:mutstr options:0 Range:range];        For (Nstextcheckingresult * match in result) {Nsrange range = [Match range];    [attr addattribute:nsforegroundcolorattributename Value:[uicolor Redcolor] range:range];    } UILabel * lbl = [[UILabel alloc]initwithframe:cgrectmake (100, 100, 200, 40)]; [SELf.view ADDSUBVIEW:LBL];    Lbl.textcolor = [Uicolor Bluecolor]; Lbl.attributedtext = attr;

　　

IOS marks all characters in a string of characters