My team and I are going to write an app for an organisation where the user can donate to this organisation. The app itself is not the problem, but we don't really know how we can handle this.
Our first thought was that we could make the donations like if you purchase an item in a game for real money. But there are 2 problems:
Our second thought was that we implement a webthingy (don't know how the element is called atm) in our app, which simply works like Safari and we direct them to the donation page or something, but how does the organisation know that the donations are from our app then?
Is there any other way we can handle this? I think people will be able to donate via credit cards and PayPal.
Edit, I found this:
21.1 Apps that include the ability to make donations to recognized charitable organizations must be free
21.2 The collection of donations must be done via a web site in Safari or an SMS
The app will be free, and it is fine if it has to be via SMS or Safari, but HOW does the organisation know the donations coming in, are from the app?
Update:
US non-profits can accept donations via Apple Pay:
Starting November 14, 2016, nonprofits based in the United States can use Apple Pay to provide a simple and secure way to accept donations from within their app and website. Similar to using Apple Pay to buy goods and services, users can donate without entering their billing, shipping, or contact details.
The App Store guidelines go on to say:
Acceptable
...
Approved nonprofits may fundraise directly within their own apps or third-party apps, provided those fundraising campaigns adhere to all App Review Guidelines and offer Apple Pay support. These apps must disclose how the funds will be used, abide by all required local and federal laws, and ensure appropriate tax receipts are available to donors. Additional information shall be provided to App Review upon request. Nonprofit platforms that connect donors to other nonprofits must ensure that every nonprofit listed in the app has also gone through the nonprofit approval process. Learn more about becoming an approved nonprofit.
Unacceptable
...
Unless you are an approved nonprofit or otherwise permitted under Section 3.2.1 (vi) above, collecting funds within the app for charities and fundraisers. Apps that seek to raise money for such causes must be free on the App Store and may only collect funds outside of the app, such as via Safari or SMS.
My old answer, below, predated this revision in the charitable giving policy.
As you note, section 21 of the App Store Review Guidelines says:
21.Charities and contributions
21.1 Apps that include the ability to make donations to recognized charitable organizations must be free
21.2 The collection of donations must be done via a web site in Safari or an SMS
You ask how you know if they're from your app: For Safari use a unique URL or include a HTTP parameter that you append to the URL when you invoke Safari, which their web server code will capture. As other have suggested, you might want to log the initiation of the transaction for your own reconciliation purposes, too. For SMS, I assume you'd have a dedicated SMS number for app donations.