From b6819711167889944497f3144e465f46f8b12514 Mon Sep 17 00:00:00 2001
From: Evan Long <evan@scribd.com>
Date: Thu, 15 Sep 2011 00:58:41 -0700
Subject: [PATCH] The allocation for the shared client could occur twice
 resulting in a leak. Two threads could pass the nil check. One would acquire
 the lock and create the sharedClient. The second thread would eventually get
 the lock and also acquire a sharedClient.

---
 Example/Classes/AFGowallaAPIClient.m | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/Example/Classes/AFGowallaAPIClient.m b/Example/Classes/AFGowallaAPIClient.m
index 9875d7913d..d8ee3118a4 100644
--- a/Example/Classes/AFGowallaAPIClient.m
+++ b/Example/Classes/AFGowallaAPIClient.m
@@ -32,11 +32,10 @@
 @implementation AFGowallaAPIClient
 
 + (id)sharedClient {
-    if (_sharedClient == nil) {
-        @synchronized(self) {
-            _sharedClient = [[self alloc] init];
-        }
-    }
+    static dispatch_once_t oncePredicate;
+    dispatch_once(&oncePredicate, ^{
+        _sharedClient = [[self alloc] init];
+    });
     
     return _sharedClient;
 }