From 9617a344082b67b760ef1e97abc0668a342d11dd Mon Sep 17 00:00:00 2001
From: zhongwuzw <zhongwuzw@qq.com>
Date: Thu, 11 Oct 2018 17:44:18 +0800
Subject: [PATCH 1/2] Fix background download operation

FIx background download

Add task check when operation will deallocated && tidy code

Tidy code further

Tidy further
---
 SDWebImage/SDWebImageDownloaderOperation.m | 49 +++++++++++-----------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/SDWebImage/SDWebImageDownloaderOperation.m b/SDWebImage/SDWebImageDownloaderOperation.m
index 427d939e..399cbd0e 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.m
+++ b/SDWebImage/SDWebImageDownloaderOperation.m
@@ -65,6 +65,11 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 @synthesize executing = _executing;
 @synthesize finished = _finished;
 
+- (void)dealloc {
+    // Edge case if user call [SDWebImageDownloaderOperation start] directly and deallocated it.
+    [self cancel];
+}
+
 - (nonnull instancetype)init {
     return [self initWithRequest:nil inSession:nil options:0];
 }
@@ -88,6 +93,9 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
         _unownedSession = session;
         _callbacksLock = dispatch_semaphore_create(1);
         _coderQueue = dispatch_queue_create("com.hackemist.SDWebImageDownloaderOperationCoderQueue", DISPATCH_QUEUE_SERIAL);
+#if SD_UIKIT
+        _backgroundTaskId = UIBackgroundTaskInvalid;
+#endif
     }
     return self;
 }
@@ -141,14 +149,7 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
             __weak __typeof__ (self) wself = self;
             UIApplication * app = [UIApplicationClass performSelector:@selector(sharedApplication)];
             self.backgroundTaskId = [app beginBackgroundTaskWithExpirationHandler:^{
-                __strong __typeof (wself) sself = wself;
-
-                if (sself) {
-                    [sself cancel];
-
-                    [app endBackgroundTask:sself.backgroundTaskId];
-                    sself.backgroundTaskId = UIBackgroundTaskInvalid;
-                }
+                [wself cancel];
             }];
         }
 #endif
@@ -212,18 +213,6 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
         [self done];
         return;
     }
-
-#if SD_UIKIT
-    Class UIApplicationClass = NSClassFromString(@"UIApplication");
-    if(!UIApplicationClass || ![UIApplicationClass respondsToSelector:@selector(sharedApplication)]) {
-        return;
-    }
-    if (self.backgroundTaskId != UIBackgroundTaskInvalid) {
-        UIApplication * app = [UIApplication performSelector:@selector(sharedApplication)];
-        [app endBackgroundTask:self.backgroundTaskId];
-        self.backgroundTaskId = UIBackgroundTaskInvalid;
-    }
-#endif
 }
 
 - (void)cancel {
@@ -262,11 +251,23 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
     SD_LOCK(self.callbacksLock);
     [self.callbackBlocks removeAllObjects];
     SD_UNLOCK(self.callbacksLock);
-    self.dataTask = nil;
     
-    if (self.ownedSession) {
-        [self.ownedSession invalidateAndCancel];
-        self.ownedSession = nil;
+    @synchronized (self) {
+        self.dataTask = nil;
+        
+        if (self.ownedSession) {
+            [self.ownedSession invalidateAndCancel];
+            self.ownedSession = nil;
+        }
+        
+#if SD_UIKIT
+        if (self.backgroundTaskId != UIBackgroundTaskInvalid) {
+            // If backgroundTaskId != UIBackgroundTaskInvalid, sharedApplication is always exist
+            UIApplication * app = [UIApplication performSelector:@selector(sharedApplication)];
+            [app endBackgroundTask:self.backgroundTaskId];
+            self.backgroundTaskId = UIBackgroundTaskInvalid;
+        }
+#endif
     }
 }
 

From de74bdca80679a2316befd4f0a377ab9f10cae2f Mon Sep 17 00:00:00 2001
From: zhongwuzw <zhongwuzw@qq.com>
Date: Wed, 26 Dec 2018 20:29:09 +0800
Subject: [PATCH 2/2] Remove edge case check

---
 SDWebImage/SDWebImageDownloaderOperation.m | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/SDWebImage/SDWebImageDownloaderOperation.m b/SDWebImage/SDWebImageDownloaderOperation.m
index 399cbd0e..65d568bd 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.m
+++ b/SDWebImage/SDWebImageDownloaderOperation.m
@@ -65,11 +65,6 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 @synthesize executing = _executing;
 @synthesize finished = _finished;
 
-- (void)dealloc {
-    // Edge case if user call [SDWebImageDownloaderOperation start] directly and deallocated it.
-    [self cancel];
-}
-
 - (nonnull instancetype)init {
     return [self initWithRequest:nil inSession:nil options:0];
 }