推荐使用富文本，比较快，先说button的title文字颜色,如下图所示
Snip20170518_5.png
UIButton *loginRegisteBtn = [UIButton buttonWithType:UIButtonTypeCustom];
loginRegisteBtn.frame = CGRectMake(20, 100, 300, 50);
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"还没有联盟账号？点击注册"];
[str addAttribute:NSForegroundColorAttributeName value:[UIColor grayColor] range:NSMakeRange(0,6)];
[str addAttribute:NSForegroundColorAttributeName value:[UIColor yellowColor] range:NSMakeRange(7,3)];
[loginRegisteBtn setAttributedTitle:str forState:UIControlStateNormal];
[self.view addSubview:loginRegisteBtn];
label 中文字的颜色
NSMutableAttributedString *companyStr = [[NSMutableAttributedString alloc] initWithString:string];
NSRange range1 = [[companyStr string]rangeOfString:redString];
[companyStr addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:range1];
applyLabel.attributedText = companyStr;
