From 30d077b0a649fabccd4324ba219250c2ddb96cae Mon Sep 17 00:00:00 2001
From: zhongwuzw <zhongwuzw@qq.com>
Date: Fri, 10 Aug 2018 22:53:13 +0800
Subject: [PATCH] Make callbacks of download more readable

---
 SDWebImage/SDWebImageDownloaderOperation.m | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/SDWebImage/SDWebImageDownloaderOperation.m b/SDWebImage/SDWebImageDownloaderOperation.m
index 2690beab..a6c13fa7 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.m
+++ b/SDWebImage/SDWebImageDownloaderOperation.m
@@ -105,15 +105,10 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 
 - (nullable NSArray<id> *)callbacksForKey:(NSString *)key {
     LOCK(self.callbacksLock);
-    NSArray<SDCallbacksDictionary *> *callbackBlocks = [self.callbackBlocks copy];
+    NSMutableArray<id> *callbacks = [[self.callbackBlocks valueForKey:key] mutableCopy];
     UNLOCK(self.callbacksLock);
-    NSMutableArray<id> *callbacks = [NSMutableArray arrayWithCapacity:callbackBlocks.count];
-    for (SDCallbacksDictionary *callbacksDic in callbackBlocks) {
-        id callback = callbacksDic[key];
-        if (callback) {
-            [callbacks addObject:callback];
-        }
-    }
+    // We need to remove [NSNull null] because there might not always be a progress block for each callback
+    [callbacks removeObjectIdenticalTo:[NSNull null]];
     return [callbacks copy]; // strip mutability here
 }