Fix/fetch product concurrency

[cipolleschi]

This PR Fixes #344 (outside of the main thread) and fixes #468.

[cipolleschi]

updated.

[cipolleschi]

I have some trouble making the test work with the CI.
Locally, they work perfectly: the execution is paused, waiting for the thread to signal the completion of the chunk of work and verify the expectation afterward.
Anyway, once executed by Travis, it looks like that the execution is not paused, and so the test fails.

Do you know how to fix this?

[Sam-Spencer]

I'm under the impression that OSSpinLock is deprecated in favor of os_unfair_lock. Is there a reason you use this here but not in tests and vice versa?

[RamyaThirunavukkarasu]

I am getting crashes while fetching the promotional code discount price details (localizedPrice and priceLocale.currencyCode) in iOS 12.5 and 13.5 but iOS 14 is working fine .

Price is coming fine but while trying to fetch localizedPrice or priceLocale.currencyCode app getting crash

I am using the latest version of SwiftyStoreKit(0.16.4)

My Xcode version is 13.1

static func getProductOfferDetails(_ productDiscount: SKProductDiscount?) -> InAppProductDiscount? {
guard let productDiscount = productDiscount else { return nil }

    var inAppProductDiscunt = InAppProductDiscount()
    inAppProductDiscunt.price = productDiscount.localizedPrice ?? String()
    inAppProductDiscunt.currency_code = productDiscount.priceLocale.currencyCode
    inAppProductDiscunt.numberOfPeriods = productDiscount.numberOfPeriods
    inAppProductDiscunt.numberOfUnits = productDiscount.subscriptionPeriod.numberOfUnits
    inAppProductDiscunt.localizedSubscriptionPeriod = productDiscount.localizedSubscriptionPeriod
    inAppProductDiscunt.unit = InAppProduct.getSubscriptionPeriodUnit(productDiscount.subscriptionPeriod.unit.rawValue)
    inAppProductDiscunt.paymentMode = inAppProductDiscunt.getPaymentMode(productDiscount.paymentMode.rawValue)
    if #available(iOS 12.2, *) {
        inAppProductDiscunt.type = inAppProductDiscunt.getType(productDiscount.type.rawValue)
        inAppProductDiscunt.identifier = productDiscount.identifier
    }
    return inAppProductDiscunt
}