It said that "PaymentWithProduct" is obsolete, and to "Use FromProduct (SKProduct) instead." at https://developer.xamarin.com/api/member/MonoTouch.StoreKit.SKPayment.PaymentWithProduct/p/MonoTouch.StoreKit.SKProduct/
Would you please help to let me know the details how to call FromProduct? And why the obsolete api is still be used in https://github.com/xamarin/ios-samples/blob/0b1bda6a7105060a4d01ffa7f9064ca4564059ac/StoreKit/SharedCode/PurchaseManager.cs
The problem is that sometimes the obsolete iOS APIs (Xamarin Studio warns) does not work really as Xamarin Studio said, but some APIs still work, like PaymentWithProduct.