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;