From 5b2859675acf0a704793c289a6a3dc2ee48cc097 Mon Sep 17 00:00:00 2001
From: Alexander Borsuk <me@alex.bio>
Date: Thu, 29 Apr 2021 23:38:16 +0200
Subject: [PATCH] [ios] Fixed observer modification crash

Signed-off-by: Alexander Borsuk <me@alex.bio>
---
 iphone/CoreApi/CoreApi/Storage/MWMStorage.mm | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/iphone/CoreApi/CoreApi/Storage/MWMStorage.mm b/iphone/CoreApi/CoreApi/Storage/MWMStorage.mm
index 12c58c8400..b5f70bbbf1 100644
--- a/iphone/CoreApi/CoreApi/Storage/MWMStorage.mm
+++ b/iphone/CoreApi/CoreApi/Storage/MWMStorage.mm
@@ -40,7 +40,10 @@ using namespace storage;
 
     GetFramework().GetStorage().Subscribe(
       [observers](CountryId const & countryId) {
-        for (id<MWMStorageObserver> observer in observers) {
+        // A copy is created, because MWMMapDownloadDialog is unsubscribed inside this notification with
+        // NSGenericException', reason: '*** Collection <NSConcreteHashTable> was mutated while being enumerated.'
+        NSHashTable *observersCopy = [observers copy];
+        for (id<MWMStorageObserver> observer in observersCopy) {
           [observer processCountryEvent:@(countryId.c_str())];
         }
       },