self.User = [[LTView alloc]initWithFrame:CGRectMake(10, 100, 295, 40)];
_User.textFiled.placeholder = @"Please Input Your Name";
核心代码
[_User.textFiled setValue:[UIColor grayColor] forKeyPath:@"_placeholderLabel.textColor"];
[_User.textFiled setValue:[UIFont boldSystemFontOfSize:15] forKeyPath:@"_placeholderLabel.font"];
_User.lable.text = @"Name";
[self addSubview:_User];
[_User release];