Created verifyPayment alternative function to return Promise

[faboyds]

Created an alternative method for verifyPayment that uses promises instead of callbacks.

Should fix #68

[ronkorving]

This removes the callback-style API from the library. In other words, while your new function works, the old one is gone (overwritten).

I would love Promise support, so I think you're on the right track here, but we need a solid solution that we can apply to all APIs, while still supporting callback-style. I think it's possible. Please reconsider a solution.

[faboyds]

Ok, I understand and I agree with you. I will take a deeper look into this when I have more time, and I'll try to deliver a more complete solution.

[superandrew213]

@faboyds have a look how I did it here: https://github.com/superandrew213/react-native-in-app-utils/blob/listen-for-purchase-event/index.js

You end up with a single method that you can call like this if you want to use callbacks:

method(arg1, arg2, (error, res) => {})

or like this if you want to use Promises:

method(arg1, arg2).then(res => {}).catch(error => {})

[justinpage]

@faboyds An alternative way you could handle this issue is through bluebird promisfy all:

http://bluebirdjs.com/docs/api/promise.promisifyall.html

Simply wrap the existing package:

const iap: any = Bluebird.promisifyAll(require("iap"));

And then you can do something like:

// Verify payment from iap service
let responseFromApple = await iap.verifyPaymentAsync(
	"apple", subscriptionWithSharedSecret
)
.catch(e => {
	logger.error(
		"Receipt.validateApplePurchase: failed to validate apple " +
		"receipt",
		{ message: e.message, subscription }
	);

	return Err("ValidationError", e.message);
});

if (isError(responseFromApple)) {
	return responseFromApple;
}

[faboyds]

@faboyds have a look how I did it here: https://github.com/superandrew213/react-native-in-app-utils/blob/listen-for-purchase-event/index.js

You end up with a single method that you can call like this if you want to use callbacks:

method(arg1, arg2, (error, res) => {})

or like this if you want to use Promises:

method(arg1, arg2).then(res => {}).catch(error => {})

I followed this implementation. Please check if the code is now meeting the requirements.
And thank you for your suggestions! 😄

[artur-ma]

Can u merge it please? @ronkorving

[ronkorving]

Done, cheers 👍

[SeanDunford]

Could we get this released on npm?

Relevant issue here #81