Add nullability specificiers.

Mobile Buy SDK/Mobile Buy SDK/Payment Providers/BUYApplePayPaymentProvider.h

@@ -27,7 +27,9 @@
 @import UIKit;
 #import "BUYPaymentProvider.h"
 
-extern NSString *const _Nonnull BUYApplePayPaymentProviderId;
+NS_ASSUME_NONNULL_BEGIN
+
+extern NSString *const BUYApplePayPaymentProviderId;
 
 @class BUYClient;
 
@@ -41,20 +43,20 @@ extern NSString *const _Nonnull BUYApplePayPaymentProviderId;
  *
  *  @return an instance of `BUYApplePayPaymentProvider`
  */
-- (instancetype _Nullable)initWithClient:(BUYClient * _Nonnull)client merchantID:(NSString * _Nonnull)merchantID NS_DESIGNATED_INITIALIZER;
-- (instancetype _Nullable)init NS_UNAVAILABLE;
+- (instancetype)initWithClient:(BUYClient *)client merchantID:(NSString *)merchantID NS_DESIGNATED_INITIALIZER;
+- (instancetype)init NS_UNAVAILABLE;
 
 /**
  *  The supported credit card payment networks.  Default values:
  *  iOS 8.3: PKPaymentNetworkAmex, PKPaymentNetworkMasterCard, PKPaymentNetworkVisa.
  *  iOS 9.0: PKPaymentNetworkAmex, PKPaymentNetworkDiscover, PKPaymentNetworkMasterCard, PKPaymentNetworkVisa.
  */
-@property (nonatomic, copy) NSArray * _Nonnull supportedNetworks;
+@property (nonatomic, copy) NSArray * supportedNetworks;
 
 /**
  *  The merchant ID required for Apple Pay
  */
-@property (nonatomic, copy, readonly) NSString * _Nonnull merchantID;
+@property (nonatomic, copy, readonly) NSString * merchantID;
 
 /**
  *  If the merchantId is set and the device support Apple Pay but no credit card is present this allows the user to add a payment pass to the Wallet.
@@ -73,3 +75,5 @@ extern NSString *const _Nonnull BUYApplePayPaymentProviderId;
 - (BOOL)canShowApplePaySetup;
 
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Payment Providers/BUYClient+Checkout.h

@@ -26,8 +26,12 @@
 
 #import <Buy/Buy.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface BUYClient (Checkout)
 
 - (NSURLSessionDataTask *)handleCheckout:(BUYCheckout *)checkout completion:(BUYDataCheckoutBlock)completion;
 
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Payment Providers/BUYPaymentController.h

@@ -27,6 +27,8 @@
 @import Foundation;
 #import "BUYPaymentProvider.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface BUYPaymentController : NSObject
 
 /**
@@ -50,7 +52,7 @@
  *
  *  @return The payment provider matching the given identifier
  */
-- (id <BUYPaymentProvider>)providerForType:(NSString *)type;
+- (id <BUYPaymentProvider> _Nullable)providerForType:(NSString *)type;
 
 /**
  *  Start a checkout
@@ -61,3 +63,5 @@
 - (void)startCheckout:(BUYCheckout *)checkout withProviderType:(NSString *)typeIdentifier;
 
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Payment Providers/BUYPaymentProvider.h

@@ -28,6 +28,8 @@
 
 #import "BUYClient.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class BUYCheckout;
 @protocol BUYPaymentProvider;
 
@@ -86,7 +88,7 @@ extern NSString *const BUYPaymentProviderDidCompleteCheckoutNotificationKey;
  *  @param provider   the `BUYPaymentProvider`
  *  @param error    the optional `NSError`
  */
-- (void)paymentProvider:(id <BUYPaymentProvider>)provider didFailCheckoutWithError:(NSError *)error;
+- (void)paymentProvider:(id <BUYPaymentProvider>)provider didFailCheckoutWithError:(NSError * _Nullable)error;
 
 /**
  *  Called when the checkout has completed
@@ -139,3 +141,5 @@ extern NSString *const BUYPaymentProviderDidCompleteCheckoutNotificationKey;
 @property (nonatomic, weak) id <BUYPaymentProviderDelegate> delegate;
 
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Payment Providers/BUYWebCheckoutPaymentProvider.h

@@ -27,9 +27,11 @@
 #import <Foundation/Foundation.h>
 #import "BUYPaymentProvider.h"
 
-extern NSString * _Nonnull BUYSafariCallbackURLNotification;
-extern NSString * _Nonnull BUYURLKey;
-extern NSString * _Nonnull const BUYWebPaymentProviderId;
+NS_ASSUME_NONNULL_BEGIN
+
+extern NSString * BUYSafariCallbackURLNotification;
+extern NSString * BUYURLKey;
+extern NSString * const BUYWebPaymentProviderId;
 
 @interface BUYWebCheckoutPaymentProvider : NSObject <BUYPaymentProvider>
 
@@ -40,7 +42,9 @@ extern NSString * _Nonnull const BUYWebPaymentProviderId;
  *
  *  @return an instance of `BUYWebCheckoutPaymentProvider`
  */
-- (instancetype _Nullable)initWithClient:(BUYClient * _Nonnull)client NS_DESIGNATED_INITIALIZER;
-- (instancetype _Nullable)init NS_UNAVAILABLE;
+- (instancetype)initWithClient:(BUYClient *)client NS_DESIGNATED_INITIALIZER;
+- (instancetype)init NS_UNAVAILABLE;
 
 @end
+
+NS_ASSUME_NONNULL_END