1、设置TextField的占位符显示placeholder_attributedPlaceholder

    // 文字属性
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    // NSAttributedString : 带有属性的文字(富文本技术)
    NSAttributedString *placeholder = [[NSAttributedString alloc] initWithString:@"手机号" attributes:attrs];
    self.phoneField.attributedPlaceholder = placeholder;

//    NSMutableAttributedString *placehoder = [[NSMutableAttributedString alloc] initWithString:@"手机号"];
//    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]} range:NSMakeRange(0, 1)];
//    [placehoder setAttributes:@{
//                                NSForegroundColorAttributeName : [UIColor yellowColor],
//                                NSFontAttributeName : [UIFont systemFontOfSize:30]
//                                } range:NSMakeRange(1, 1)];
//    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor redColor]} range:NSMakeRange(2, 1)];
//    self.phoneField.attributedPlaceholder = placehoder;