Merge pull request #558 from yanyin1986/master

init _cacheQueue when AVCacheManager init.

Author: zapcannon87

AVOS/AVOSCloud/Cache/AVCacheManager.m

@@ -34,6 +34,14 @@ + (AVCacheManager *)sharedInstance {
     return _sharedInstance;
 }
 
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        _cacheQueue = dispatch_queue_create("avos.paas.cacheQueue", DISPATCH_QUEUE_SERIAL);
+    }
+    return self;
+}
+
 #pragma mark - Accessors
 + (NSString *)path {
     return [AVPersistenceUtils avCacheDirectory];
@@ -46,13 +54,6 @@ - (NSString *)diskCachePath {
     return _diskCachePath;
 }
 
-- (dispatch_queue_t)cacheQueue {
-    if (!_cacheQueue) {
-        _cacheQueue = dispatch_queue_create("avos.paas.cacheQueue", DISPATCH_QUEUE_SERIAL);
-    }
-    return _cacheQueue;
-}
-
 - (NSString *)pathForKey:(NSString *)key {
     return [self.diskCachePath stringByAppendingPathComponent:key];
 }