Multiple protocols

I'm declaring that my app delegate conforms to the protocols

<UIApplicationDelegate, SKPaymentTransactionObserver>

in the app delegate header file (i.e. the app delegate interface).

The compiler tells me at numer开发者_如何学编程ous places in my code that:

warning: type 'id <UIApplicationDelegate>' does not conform to the 'SKPaymentTransactionObserver' protocol

What's up?

---

You're probably doing something like [[SKPaymentQueue defaultQueue] addTransactionObserver:[[UIApplication sharedApplication] delegate]]. Since -[UIApplication delegate] is declared as returning id<UIApplicationDelegate>, the compiler has no way of knowing that the object returned will implement the SKPaymentTransactionObserver protocol. Try assigning the delegate to a variable that's statically typed as your delegate class and pass that to the method you're trying to call and the compiler should be happy.

---

Your ApplicationDelegate seems to be missing some of the required delegates, for example:

- (void)applicationWillResignActive:(UIApplication *)application

Check what delegate methods SKPaymentTransactionObserver requires, and add them to your AppDelegate.m

Also, check over the SKPaymentTransactionObserver Protocol Reference