JewelBox

JewelBox.h

//
//  JewelBox.h
//  Clomp
//
//  Created by Andrei on 8/12/12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface JewelBox : NSObject

@property (nonatomic, retain) NSFileManager *fileManager;

+ (JewelBox *)box;

- (BOOL)hasJewelFromURL:(NSString *)url;
- (id)jewelForURL:(NSString *)url;

- (UIImage *)imageForURL:(NSString *)url;

- (void)storeJewel:(NSData *)jewel forURL:(NSString *)url;
- (void)storeImage:(UIImage *)image forURL:(NSString *)url;

- (void)throwAwayOldJewels;
- (void)throwAwayAllJewels;

// JewelBox helpers
- (NSString *)cachesPath;
- (NSString *)pathForURL:(NSString *)url;

@end

JewelBox.m

//
//  JewelBox.m
//  Clomp
//
//  Created by Andrei on 8/12/12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import "JewelBox.h"
#import "NGUtils.h"

#define TenDaysInSeconds (60 * 60 * 24 * 10)

@implementation JewelBox

@synthesize fileManager;

+ (JewelBox *)box {
    static JewelBox *box = nil;
    if (box == nil) {
        box = [JewelBox new];        
    }
    return box;
}

- (id)init {
    if (self = [super init]) {
        self.fileManager = [[[NSFileManager alloc] init] autorelease];
    }
    return self;
}

- (NSString *)cachesPath {
    static NSString *cachesPath = nil;
    if (cachesPath == nil) {
        NSArray *urls = [self.fileManager URLsForDirectory:NSCachesDirectory 
                                                 inDomains:NSUserDomainMask];
        cachesPath = [[(NSURL *)[urls lastObject] path] retain];
    }
    return cachesPath;
}

- (NSString *)pathForURL:(NSString *)url {
    if (url) {
        return [[self cachesPath] stringByAppendingPathComponent:[url simpleHash]];
    }
    return nil;
}

- (BOOL)hasJewelFromURL:(NSString *)url {
    return [self.fileManager fileExistsAtPath:[self pathForURL:url]];
}

- (id)jewelForURL:(NSString *)url {
    return [NSData dataWithContentsOfFile:[self pathForURL:url]];
}

- (UIImage *)imageForURL:(NSString *)url {
    return [UIImage imageWithContentsOfFile:[self pathForURL:url]];
}

- (void)storeJewel:(NSData *)jewel forURL:(NSString *)url {
    NSLog(@"saving file ...");
    [jewel writeToFile:[self pathForURL:url] 
            atomically:YES];
}

- (void)storeImage:(UIImage *)image forURL:(NSString *)url {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
        NSData *jewel = UIImagePNGRepresentation(image);
        [self storeJewel:jewel forURL:url];
    });
}

- (void)throwAwayJewlsOlderThan:(double)seconds {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
        // NSFileManager is not thread safe 
        NSFileManager *fileManeger = [[NSFileManager alloc] init];
        
        NSMutableArray *oldJewels = [NSMutableArray array];

        NSDirectoryEnumerator *dirEnum = [fileManeger enumeratorAtPath:[self cachesPath]];
        NSURL *url = nil;
        NSDate *currentDate = [NSDate date];
        while ((url = [dirEnum nextObject])) {
            NSDate *modDate = [[dirEnum fileAttributes] objectForKey:NSFileModificationDate];
            if (modDate && 
                [currentDate compare:[modDate dateByAddingTimeInterval:seconds]] == NSOrderedDescending) {
                [oldJewels addObject:url];
            }
        }                
        
        for (NSString *path in oldJewels) {
            [fileManeger removeItemAtPath:[[self cachesPath] stringByAppendingPathComponent:path] 
                           error:NULL];
        }
        
        [fileManeger release];
    });     
}

- (void)throwAwayOldJewels {
    [self throwAwayJewlsOlderThan:TenDaysInSeconds];
}

- (void)throwAwayAllJewels {
    [self throwAwayJewlsOlderThan:0];
}

- (void)dealloc {
    self.fileManager = nil;
    
    [super dealloc];
}

@end