I have been trying to use Amazon Pinpoint to run push notification campaign for iOS using the sample app to no avail. For Android, it was successful though. I tried pushing using APNS directly and Amazon SNS, both were successful.
I am suspecting that there are some certification issues relating to iOS. I used this documentation guide to obtain the .p12 certificate to upload to 'Manage - Channel' section of the Pinpoint interface and also for Amazon SNS.
http://docs.aws.amazon.com/mobile-hub/latest/developerguide/ios-appid-setup.html
The devices were detected but the messages weren't delivered to iOS. In the screenshot below, the delivered count is for Android device (2 iOS device, 1 Android).
Any help will be greatly appreciated. Thanks!!