From ebf41a3b0107a768845d0352b1c5212503d07c03 Mon Sep 17 00:00:00 2001
From: zhongwuzw <zhongwuzw@qq.com>
Date: Tue, 19 Mar 2019 20:26:00 +0800
Subject: [PATCH] Consolidate cancel code

---
 SDWebImage/SDWebImagePrefetcher.m | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/SDWebImage/SDWebImagePrefetcher.m b/SDWebImage/SDWebImagePrefetcher.m
index ddf532e7..c40055ec 100644
--- a/SDWebImage/SDWebImagePrefetcher.m
+++ b/SDWebImage/SDWebImagePrefetcher.m
@@ -263,8 +263,9 @@
     @synchronized (self) {
         [self.prefetchOperations compact];
         for (id operation in self.prefetchOperations) {
-            SDAsyncBlockOperation *asyncBlockOperation = operation;
-            [asyncBlockOperation cancel];
+            if ([operation conformsToProtocol:@protocol(SDWebImageOperation)]) {
+                [operation cancel];
+            }
         }
         self.prefetchOperations.count = 0;