Allow products to be fetched even if purchases are restricted (#123)

Restricting IAPs doesn't prevent us from fetching product information. A better way to handle this is to check canMakePayments method and show appropriate message on the payment screen.

Update README to include canMakePayments

Also add note about calling canMakePayments before purchaseProduct to show a better error message to users.

Author: akshetpandey

InAppUtils/InAppUtils.m

@@ -191,15 +191,11 @@ - (void)paymentQueueRestoreCompletedTransactionsFinished:(SKPaymentQueue *)queue
 RCT_EXPORT_METHOD(loadProducts:(NSArray *)productIdentifiers
                   callback:(RCTResponseSenderBlock)callback)
 {
-    if([SKPaymentQueue canMakePayments]){
-        SKProductsRequest *productsRequest = [[SKProductsRequest alloc]
-                                              initWithProductIdentifiers:[NSSet setWithArray:productIdentifiers]];
-        productsRequest.delegate = self;
-        _callbacks[RCTKeyForInstance(productsRequest)] = callback;
-        [productsRequest start];
-    } else {
-        callback(@[@"not_available"]);
-    }
+    SKProductsRequest *productsRequest = [[SKProductsRequest alloc]
+                                          initWithProductIdentifiers:[NSSet setWithArray:productIdentifiers]];
+    productsRequest.delegate = self;
+    _callbacks[RCTKeyForInstance(productsRequest)] = callback;
+    [productsRequest start];
 }
 
 RCT_EXPORT_METHOD(canMakePayments: (RCTResponseSenderBlock)callback)

Readme.md

@@ -61,6 +61,18 @@ InAppUtils.loadProducts(products, (error, products) => {
 
 **Troubleshooting:** If you do not get back your product(s) then there's a good chance that something in your iTunes Connect or Xcode is not properly configured. Take a look at this [StackOverflow Answer](http://stackoverflow.com/a/11707704/293280) to determine what might be the issue(s).
 
+### Checking if payments are allowed
+
+```javascript
+InAppUtils.canMakePayments((canMakePayments) => {
+   if(!canMakePayments) {
+      Alert.alert('Not Allowed', 'This device is not allowed to make purchases. Please check restrictions on device');
+   }
+})
+```
+
+**NOTE:** canMakePayments may return false because of country limitation or parental contol/restriction setup on the device.
+
 ### Buy product
 
 ```javascript
@@ -76,6 +88,8 @@ InAppUtils.purchaseProduct(productIdentifier, (error, response) => {
 
 **NOTE:** Call `loadProducts` prior to calling `purchaseProduct`, otherwise this will return `invalid_product`. If you're calling them right after each other, you will need to call `purchaseProduct` inside of the `loadProducts` callback to ensure it has had a chance to complete its call.
 
+**NOTE:** Call `canMakePurchases` prior to calling `purchaseProduct` to ensure that the user is allowed to make a purchase. It is generally a good idea to inform the user that they are not allowed to make purchases from their account and what they can do about it instead of a cryptic error message from iTunes.
+
 **NOTE:** `purchaseProductForUser(productIdentifier, username, callback)` is also available.
 https://stackoverflow.com/questions/29255568/is-there-any-way-to-know-purchase-made-by-which-itunes-account-ios/29280858#29280858