Re-add property and mark as deprecated

Mobile Buy SDK/Mobile Buy SDK/Models/BUYCheckout.h

@@ -149,6 +149,11 @@
 @property (nonatomic, strong) BUYShippingRate *shippingRate;
 
 /**
+*  Shipping rate identifier
+*/
+@property (nonatomic, readonly) NSString *shippingRateId DEPRECATED_MSG_ATTRIBUTE("Use shippingRate.shippingRateIdentifier");
+
+/**
  *  A discount added to the checkout
  *  Only one discount can be added to a checkout. Call `updateCheckout:completion:`
  *  after adding a discount to apply the discount code to the checkout.

Mobile Buy SDK/Mobile Buy SDK/Models/BUYCheckout.m

@@ -155,6 +155,11 @@
 	self.sourceIdentifier = dictionary[@"source_identifier"];
 }
 
+- (NSString *)shippingRateId
+{
+	return self.shippingRate.shippingRateIdentifier;
+}
+
 - (id)jsonValueForValue:(id)value
 {
 	id newValue = value;