From ee20fd8fd8912faa7662e4ea61aaaf9368af4048 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Minh=20Nguye=CC=82=CC=83n?= <mxn@1ec5.org>
Date: Thu, 10 Mar 2016 16:04:18 -0800
Subject: [PATCH] [ios, osx] Avoid unregistering observer for invalid task

---
 platform/darwin/src/MGLOfflineTask.mm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/platform/darwin/src/MGLOfflineTask.mm b/platform/darwin/src/MGLOfflineTask.mm
index 4698a492f..d105218ed 100644
--- a/platform/darwin/src/MGLOfflineTask.mm
+++ b/platform/darwin/src/MGLOfflineTask.mm
@@ -66,8 +66,10 @@ private:
 }
 
 - (void)dealloc {
-    mbgl::DefaultFileSource *mbglFileSource = [[MGLOfflineStorage sharedOfflineStorage] mbglFileSource];
-    mbglFileSource->setOfflineRegionObserver(*_mbglOfflineRegion, nullptr);
+    if (_mbglOfflineRegion && _state != MGLOfflineTaskStateInvalid) {
+        mbgl::DefaultFileSource *mbglFileSource = [[MGLOfflineStorage sharedOfflineStorage] mbglFileSource];
+        mbglFileSource->setOfflineRegionObserver(*_mbglOfflineRegion, nullptr);
+    }
 }
 
 - (id <MGLOfflineRegion>)region {