ADD: add an image cache util.

Author: tangqiaoboy

TQImageCache/TQImageCache.h

@@ -0,0 +1,22 @@
+//
+//  TQImageCAche.h
+//
+//
+//  Created by Tang Qiao on 12-5-9.
+//  Copyright (c) 2012年 blog.devtang.com. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@interface TQImageCache : NSObject
+
+@property (nonatomic, assign) NSInteger maxMemoryCacheNumber;
+
+
+- (id) initWithCachePath:(NSString*)path andMaxMemoryCacheNumber:(NSInteger)maxNumber;
+
+- (void) putImage:(NSData *) imageData withName:(NSString*)imageName ;
+- (NSData *) getImage:(NSString *)imageName;
+- (void)clear;
+
+@end

TQImageCache/TQImageCache.m

@@ -0,0 +1,124 @@
+//
+//  TQImageCache.m
+//
+//
+//  Created by Tang Qiao on 12-5-9.
+//  Copyright (c) 2012年 blog.devtang.com. All rights reserved.
+//
+
+#import "TQImageCache.h"
+
+@interface TQImageCache()
+
+@property (nonatomic, retain) NSString * cachePath;
+@property (nonatomic, retain) NSFileManager * fileManager;
+@property (nonatomic, retain) NSMutableDictionary * memoryCache;
+@property (nonatomic, retain) NSMutableArray *memoryCacheKeys;
+
+@end
+
+@implementation TQImageCache;
+
+@synthesize maxMemoryCacheNumber;
+@synthesize cachePath;
+@synthesize fileManager;
+@synthesize memoryCache;
+@synthesize memoryCacheKeys;
+
+static BOOL debugMode = YES;
+
+#ifdef DEBUG
+#define debugLog(...) NSLog(__VA_ARGS__)
+#define debugMethod() NSLog(@"%s", __func__)
+#else
+#define debugLog(...)
+#define debugMethod()
+#endif
+
+- (id) init {
+    return [self initWithCachePath:@"TQImageCache" andMaxMemoryCacheNumber:50];
+}
+
+- (id) initWithCachePath:(NSString*)path andMaxMemoryCacheNumber:(NSInteger)maxNumber {
+    if ([path hasPrefix:NSTemporaryDirectory()]) {
+        self.cachePath = path;
+    } else {
+        if ([path length] != 0) {
+            self.cachePath = [NSTemporaryDirectory() stringByAppendingPathComponent:path];
+        } else {
+            return nil;
+        }
+    }
+    self.maxMemoryCacheNumber = maxNumber;
+
+    if (self = [super init]) {
+        self.fileManager = [NSFileManager defaultManager];
+        if ([self.fileManager fileExistsAtPath:self.cachePath isDirectory:nil] == NO) {
+            // create the directory
+            BOOL res = [self.fileManager createDirectoryAtPath:self.cachePath withIntermediateDirectories:YES attributes:nil error:nil];
+            if (!res) {
+                debugLog(@"file cache directory create failed! The path is %@", self.cachePath);
+                return nil;
+            }
+        }
+        self.memoryCache = [[[NSMutableDictionary alloc] initWithCapacity:maxMemoryCacheNumber] autorelease];
+        self.memoryCacheKeys = [[[NSMutableArray alloc] initWithCapacity:maxMemoryCacheNumber] autorelease];
+        return self;
+    }
+    return self;
+}
+
+- (void)clear {
+    self.memoryCache = [[[NSMutableDictionary alloc] initWithCapacity:maxMemoryCacheNumber] autorelease];
+    self.memoryCacheKeys = [[[NSMutableArray alloc] initWithCapacity:maxMemoryCacheNumber] autorelease];
+
+    // remove all the file in temporary
+    NSArray * files = [self.fileManager contentsOfDirectoryAtPath:self.cachePath error:nil];
+    for (NSString * file in files) {
+        if (debugMode) {
+            debugLog(@"remove cache file: %@", file);
+        }
+        [self.fileManager removeItemAtPath:file error:nil];
+    }
+}
+
+- (void) putImage:(NSData *) imageData withName:(NSString*)imageName {
+    [self.memoryCache setObject:imageData forKey:imageName];
+    [self.memoryCacheKeys addObject:imageName];
+    if ([self.memoryCache count] > self.maxMemoryCacheNumber) {
+        // Retain the `key` varible otherwise
+        // it maybe dealloc after it is removed from memoryCahceKyes array
+        NSString * key = [[self.memoryCacheKeys objectAtIndex:0] retain];
+        [self.memoryCache removeObjectForKey:key];
+        [self.memoryCacheKeys removeObjectAtIndex:0];
+        if (debugMode) {
+            debugLog(@"remove oldest cache from memory: %@", key);
+        }
+        [key release];
+    }
+    NSString * path = [self.cachePath stringByAppendingPathComponent:imageName];
+    [imageData writeToFile:path atomically:YES];
+    if (debugMode) {
+        debugLog(@"TQImageCache put cache image to %@", path);
+    }
+}
+
+- (NSData *) getImage:(NSString *)imageName {
+    NSData * data = [self.memoryCache objectForKey:imageName];
+    if (data != nil) {
+        if (debugMode) {
+            debugLog(@"TQImageCache hit cache from memory: %@", imageName);
+        }
+        return data;
+    }
+    NSString * path = [self.cachePath stringByAppendingPathComponent:imageName];
+    if ([self.fileManager fileExistsAtPath:path]) {
+        if (debugMode) {
+            debugLog(@"TQImageCache hit cache from file %@", path);
+        }
+        return [NSData dataWithContentsOfFile:path];
+    }
+    return nil;
+}
+
+@end