Add GCReusableQueue

GCReusableQueue/GCReusableQueue.h

@@ -0,0 +1,27 @@
+//
+//  GCReusableQueue.h
+//  GCReusableQueue
+//
+//  Created by Glenn Chiu on 31-05-12.
+//  Copyright (c) 2012 Dot Square. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+/* Make sure that objects conform to this protocol and return -reuseIdentifier. */
+@protocol ReusableObject <NSObject>
+
+- (NSString *)reuseIdentifier;
+
+@end
+
+@interface GCReusableQueue : NSObject
+
+- (void)enqueueReusableObject:(id <ReusableObject>)obj;
+- (id <ReusableObject>)dequeueReusableObjectWithIdentifier:(NSString *)identifier;
+
+/* This method should not be used, as the queue will discard objects automatically
+   when memory gets tight. Use this method to discard objects manually. */
+- (void)clearQueue;
+
+@end

GCReusableQueue/GCReusableQueue.m

@@ -0,0 +1,94 @@
+//
+//  GCReusableQueue.m
+//  GCReusableQueue
+//
+//  Created by Glenn Chiu on 31-05-12.
+//  Copyright (c) 2012 Dot Square. All rights reserved.
+//
+
+#import "GCReusableQueue.h"
+#import <TargetConditionals.h>
+
+@implementation GCReusableQueue
+{
+    NSCache *_reusableObjects;
+    id _observer;
+}
+
+- (id)init
+{
+    self = [super init];
+    if (self)
+    {
+
+#if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
+
+        __weak GCReusableQueue *w_self = self;
+
+        self->_observer = [[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationDidReceiveMemoryWarningNotification 
+                                                                            object:nil 
+                                                                             queue:nil 
+                                                                        usingBlock:^(NSNotification *note) {
+                                                                            GCReusableQueue *s_self = w_self;
+
+                                                                            [s_self clearQueue];
+                                                                        }];
+
+#endif
+
+    }
+    return self;
+}
+
+- (void)dealloc
+{
+    [[NSNotificationCenter defaultCenter] removeObserver:self->_observer];
+}
+
+- (NSCache *)reusableObjects
+{
+    if (!self->_reusableObjects)
+    {
+        self->_reusableObjects = [NSCache new];
+    }
+
+    return self->_reusableObjects;
+}
+
+- (id <ReusableObject>)dequeueReusableObjectWithIdentifier:(NSString *)identifier
+{
+	NSParameterAssert(identifier);
+
+	NSMutableSet *objects = [[self reusableObjects] objectForKey:identifier];
+
+	id <ReusableObject> obj = [objects anyObject];
+
+	if (obj)
+	{
+		[objects removeObject:obj];
+	}
+
+	return obj;
+}
+
+- (void)enqueueReusableObject:(id <ReusableObject>)obj
+{	
+	NSMutableSet *objects = [[self reusableObjects] objectForKey:[obj reuseIdentifier]];
+
+	if (!objects)
+	{
+		objects = [NSMutableSet set];
+		[[self reusableObjects] setObject:objects forKey:[obj reuseIdentifier]];
+	}
+	else
+	{
+        [objects addObject:obj];
+	}
+}
+
+- (void)clearQueue
+{
+    [[self reusableObjects] removeAllObjects];
+}
+
+@end