[ios, osx] Invalidate packs upon reload

platform/darwin/src/MGLOfflinePack_Private.h

@@ -33,7 +33,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 /**
  Invalidates the pack and ensures that no future progress update can ever
- revalidate it.
+ revalidate it. This method must be called before the pack is deallocated.
  */
 - (void)invalidate;
 

platform/darwin/src/MGLOfflineStorage.mm

@@ -195,6 +195,9 @@ NSString * const MGLOfflinePackMaximumCountUserInfoKey = @"MaximumCount";
 
 - (void)reloadPacks {
     [self getPacksWithCompletionHandler:^(NS_ARRAY_OF(MGLOfflinePack *) *packs, __unused NSError * _Nullable error) {
+        for (MGLOfflinePack *pack in self.packs) {
+            [pack invalidate];
+        }
         self.packs = [packs mutableCopy];
         
         for (MGLOfflinePack *pack in packs) {