最近公司项目增加了个需求：为了更好的用户体验，节省用户流量，需要实现离线缓存功能
针对这个需求临时创建了一个简易的缓存管理类，负责管理缓存，其可对数据进行缓存或从缓存中取出或删除缓存。
创建缓存目录：
- (id)init
{
if ((self = [super init])) {
// 创建缓存目录
NSString* cachesDirectory = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];
_directory = [[[cachesDirectory stringByAppendingPathComponent:[[NSBundle mainBundle] bundleIdentifier]] stringByAppendingPathComponent:@"XXXXXX"] copy];
[[NSFileManager defaultManager]createDirectoryAtPath:_directory withIntermediateDirectories:YES attributes:nil error:NULL];
// 获取后台优先级的、并发的、全局的线程队列
_diskQueue = dispatch_queue_create("com.XXXXXX.cache", DISPATCH_QUEUE_SERIAL);
dispatch_queue_t priority = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
dispatch_set_target_queue(priority, _diskQueue);
}
return self;
}
把数据写入缓存：
- (void)setObject:(id)anObject forKey:(NSString*)key
{
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:anObject];
NSString* cachePath = cachePathForKey(_directory, key);
dispatch_async(_diskQueue, ^{
[data writeToFile:cachePath atomically:YES];
});
}
从缓存中取出数据:
- (id<NSCoding>)objectForKey:(NSString*)key{
if([self hasCacheForKey:key]) {
NSData *data = [NSData dataWithContentsOfFile:cachePathForKey(_directory, key) options:0 error:NULL];
return [NSKeyedUnarchiver unarchiveObjectWithData:data];
}else {
return nil;
}
}
清除缓存数据：
- (void)clearAllCache{
dispatch_sync(_diskQueue, ^{
NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:_directory];
NSString *fileName;
while (fileName= [dirEnum nextObject]) {
[[NSFileManager defaultManager] removeItemAtPath: [NSString stringWithFormat:@"%@/%@",_directory, fileName] error:NULL]; }
});
}
