监听一个对象的值和熟悉的改变 先构造出这个对象， _pass = [[PassGuardTextFieldalloc] initWithFrame:CGRectZero]; _pass.leftView = view2; _pass.leftViewMode =UITextFieldViewModeAlways; _pass.placeholder =@"输 Other 2023-11-16 78 点赞 1 评论 118 浏览
