您可以在您的应用中制作注册表单.但是您绝对不能在您的应用程序中显示具有其他付款方式的网站.Apple 将拒绝该应用.

You can make a registration form in your app. But you definately cannot show a website with other payment methods inside your app. Apple will reject the app.

***对苹果隐藏其他付款方式.

It is best to hide other payment methods from apple alltogether.

至于免费下载部分.这是允许的，苹果不能阻止你向你的客户提供免费的东西.在外部网站上授权的登录就可以了.但只要他们看不到您使用其他付款方式:)

As for the free downloads part. It's allowed, apple can't stop you from giving free stuff to your customers. A login authorizing at the external website is just fine. But as long as they can't see your using other payment methods :).