清理缓存

//清理缓存
-(void) clearCache
{
    dispatch_async(
                   dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
                   , ^{
                       
                       NSString *cachPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0];
                       NSArray *files = [[NSFileManager defaultManager] subpathsAtPath:cachPath];

                       for (NSString *p in files) {
                           NSError *error;
                           NSString *path = [cachPath stringByAppendingPathComponent:p];
                           if ([[NSFileManager defaultManager] fileExistsAtPath:path]) {
                               [[NSFileManager defaultManager] removeItemAtPath:path error:&error];
                           }
                       }
                       [self performSelectorOnMainThread:@selector(clearCacheSuccess)
                                              withObject:nil waitUntilDone:YES];});
}