Am I allowed to offer payments with a 3rd party payment gateway, for my iPhone app?

Question

So I have a RESTful Api service which has free and pay'ed stuff. Anyone can create an iPhone/Andriod/MSPhone app that leverages our api.

Bad analogy: imagine we're creating a chat api service for Steam .. and you can pay for more people in your friends list, instead of getting them via steam-experience/steam-levels. So now anyone can create a chat client (on any platform) .. and they use our REST api.

So, for anyone creating an iPhone app, are we allowed to accept credit card details and HTTPS POST them to our webserver .. where we call another payment gateway (eg. Stripe, paypal, etc.) to do the processing.

WE NEVER STORE ANYTHING ** (besides the receipt from Stripe, etc.)

Are well allowed to program this into our iPhone app? Or is that illegal? Can we also offer bitcoins as a payment option?

(Note: we're not really using Stripe .. but they are a well known payment processor, which helps explain this question).

Answer 1

Below news is a big win for iOS developers. If it comes to effect then nothing like it.

https://in.pcmag.com/iphone-apps/144790/judge-apple-must-let-ios-apps-include-third-party-payment-options

Judge: Apple Must Let iOS Apps Include Third-Party Payment Options. The injunction, which takes effect in 90 days, threatens to upend Apple’s control over the iOS ecosystem.

As per this rule, no matter what you are selling from iOS apps, developers should be allowed to use 3rd party payment gateways.

Answer 2

1. For real goodies you can not use IAP.
2. For virtual goodies consumed into your app you are allowed to integrate 3rd party payment gateway as long as you also implement IAP. Also note the price for your product through the IAP shall not be higher then through 3rd party payment gateway.
3. Also thing about your product, if it is non-consumable you need to provide mechanism to restore the purchase.