iOS 清除系统缓存

######  直接调用这个方法就可以
// 显示缓存大小
-(float)filePath {
    NSString * cachPath = [ NSSearchPathForDirectoriesInDomains ( NSCachesDirectory , NSUserDomainMask , YES ) firstObject ];
    return [ self folderSizeAtPath :cachPath];
}
//1:首先我们计算一下 单个文件的大小

- (long long) fileSizeAtPath:( NSString *) filePath {
    
    NSFileManager * manager = [ NSFileManager defaultManager ];
    if ([manager fileExistsAtPath :filePath]){
        return [[manager attributesOfItemAtPath :filePath error : nil ] fileSize ];
    }
    return 0 ;
    
}
//2:遍历文件夹获得文件夹大小，返回多少 M（提示：你可以在工程界设置（)m）

- (float) folderSizeAtPath:( NSString *) folderPath{
    
    NSFileManager * manager = [ NSFileManager defaultManager ];
    
    if (![manager fileExistsAtPath :folderPath]) return 0 ;
    
    NSEnumerator *childFilesEnumerator = [[manager subpathsAtPath :folderPath] objectEnumerator ];
    
    NSString * fileName;
    
    long long folderSize = 0 ;
    while ((fileName = [childFilesEnumerator nextObject ]) != nil ){
        NSString * fileAbsolutePath = [folderPath stringByAppendingPathComponent :fileName];
        folderSize += [ self fileSizeAtPath :fileAbsolutePath];
    }
    return folderSize / ( 1024.0 * 1024.0 );
    
}

// 清理缓存

- (void)clearFile{
    NSString * cachPath = [ NSSearchPathForDirectoriesInDomains ( NSCachesDirectory , NSUserDomainMask , YES ) firstObject ];
    
    NSArray * files = [[ NSFileManager defaultManager ] subpathsAtPath :cachPath];
    
    NSLog ( @"cachpath = %@" , cachPath);
    
    for ( NSString * p in files) {
        
        NSError * error = nil ;
        
        NSString * path = [cachPath stringByAppendingPathComponent :p];
        
        if ([[ NSFileManager defaultManager ] fileExistsAtPath :path]) {
            
            [[ NSFileManager defaultManager ] removeItemAtPath :path error :&error];
            
        }
        
    }
    
    [ self performSelectorOnMainThread : @selector (clearCachSuccess) withObject : nil waitUntilDone : YES ];
    
}

-(void)clearCachSuccess{
    NSLog ( @"清理成功" );
    NSIndexPath *index=[NSIndexPath indexPathForRow:0 inSection:0];//刷新
    [_tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:index,nil] withRowAnimation:UITableViewRowAnimationNone];
}