uitableview 下上滚动

uitableview 上下滚动
    table = [[PullToRefreshTableView alloc] initWithFrame:CGRectMake(0, 45, 320, 480)];
    [table setContentSize:CGSizeMake(320, 960)];
    //table.contentSize = CGRectMake(0, 0, 320, 960);
    table.delegate = self;
    table.dataSource = self;
    table.backgroundColor = [UIColor clearColor];
    [self.view addSubview:table];