给label text 上色 && 给textfiled placeholder 上色

NSInteger stringLength = 0;   
        stringLength = model.ToUserNickName.length;
        NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:string];
        NSLog(@"textLength is %u", model.ToUserNickName.length);
        [str addAttribute:NSForegroundColorAttributeName value:[UIColor grayColor] range:NSMakeRange(2,stringLength)];
        self.CommentContent.attributedText = str;     // self.CommentContent.attributedText  是一个 label

textField.placeholder = @"username is in here!";  
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];  
[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"]; 


// 转自 http://blog.csdn.net/woaifen3344/article/details/38352015