Define STOREKIT_REVIEW_AVAILABLE flag to indicate whether SKStokeReviewController exists for lower versions of XCode.
Boolean flag useSKStoreReviewControllerIfAvailable is also removed because without SKStokeReviewController this is flag is meaningless.
Define
STOREKIT_REVIEW_AVAILABLE
flag to indicate whetherSKStokeReviewController
exists for lower versions of XCode. Boolean flaguseSKStoreReviewControllerIfAvailable
is also removed because withoutSKStokeReviewController
this is flag is meaningless.