变字符特定位置的颜色

- (void)viewDidLoad {
    [super viewDidLoad];
    NSString *jtgz = @"11111111";
    
    NSString *strJTGZ = [NSString stringWithFormat:@"交通管制%d处 ",[jtgz intValue]];
    NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc]initWithString:strJTGZ];
    [attributedStr addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(4, jtgz.length)];
//    [mutableStr appendAttributedString:attributedStr];
    
    _test.attributedText = attributedStr;

}

效果：