I have a strong feeling that when your local station's pledge drive begins, the app will use your location data to generate notifications about donating, which you'll be able to do through the app.
At least, that's how I would do it. NPR is missing out on a big donation opportunity by not taking advantage of an app store's built-in in-app purchase/donation infrastructure.
Unfortunately Apple's ToS explicitly forbid charitable donations inside of apps, which is exactly what an IAP donation would be. Public radio's hands are tied unless Apple changes it's policies.
It already includes a donation link under the station name. Right now it just sends you an email with donation info. Hopefully they can streamline that in the future.
At least, that's how I would do it. NPR is missing out on a big donation opportunity by not taking advantage of an app store's built-in in-app purchase/donation infrastructure.