Is it allowed to ask users to enter credit card details for own payment method?

It seems to me Apple won't allow this, but I need to make sure.

For an app we're building, we want to ask the user to enter payment information (including credit card details) to pay for tickets. The transaction will be completed by calling a webservice of our service provider. The application we're developing will be a front-end for the services of our service provider.

Please Note: We wouldn't be using Apple's in-app purchasing (IAP) system for this transaction.

I'm concerned about the following point from Apple's developer license agreement:

11.2 
Apps utilizing a system other than the In App Purchase API (IAP) to purchase 
content, functionality,开发者_高级运维 or services in an app will be rejected.

I've seen apps use webviews to complete payments and that seems to be allowed. We'd like to use native controls for users to enter payment details.

That only applies to content for an app, functionality for an app, or services related to the app. You'll be fine (though, you should make sure you let users known that you're using SSL, etc). The problem'll be that your users probably won't trust you, since they probably only trust a browser telling them they're using a https connection.