简单而又少的数据缓存策略

+ (void)cacheDictionary:(NSDictionary *)dictionary FileName:(NSString *)fileName{

    

    NSArray *cachePath = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);

    NSString * pathStr = cachePath.firstObject;／／存在这里 删除程序缓存就没了 

//    NSString *path = NSTemporaryDirectory();存在这里程序从后台关掉就没有缓存了

    NSString* file = [pathStr stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@",fileName]];

    NSData* cacheData = [NSKeyedArchiver archivedDataWithRootObject:dictionary];

    [cacheData writeToFile:file atomically:YES];

}

+ (NSDictionary *)dictionaryWithFileName:(NSString *)fileName{

    NSArray *cachePath = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);

    NSString * path = cachePath.firstObject;

//    NSString *path = NSTemporaryDirectory();

    NSString* file = [path stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@",fileName]];

    NSData* data = [NSData dataWithContentsOfFile:file];

    NSDictionary* dic = [NSKeyedUnarchiver unarchiveObjectWithData:data];

    return dic;

}