iPhone项目需要"上拉刷新"功能

Question

许多iPhone项目使用"Pull-to-Refresh"模式来加载更多结果(通常是来自服务器的新数据).

在我的项目中,我想做的恰恰相反:"拉起来刷新".我想从服务器加载旧数据,但我需要用户请求提取UITableView的数据.

我该怎么做？有谁能够帮我？

Answer 1

这是我一直在使用的:

首先,您有一个视图,其中包含"拉起刷新消息",并将其分配给:

[pullUpView setFrame:CGRectMake(0, [tableView rectForFooterInSection:0].origin.y, [tableView bounds].size.width,pullUpView.frame.height)];

然后设置两个委托方法,如下所示,以跟踪拖动.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {    
    if (scrollView.isDragging) {
        CGFloat thresholdToRelease = [pullUpView frame].origin.y - [scrollView bounds].size.height;
        CGFloat thresholdToLoad = thresholdToRelease + [pullUpView frame].size.height;

        if (([scrollView contentOffset].y >= thresholdToRelease) && ([scrollView contentOffset].y < thresholdToLoad)) {
            [pullUpView reset];
        } else if ([scrollView contentOffset].y >= thresholdToLoad) {
            [pullUpView indicateThresholdRearched];
        }
    }
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    CGFloat thresholdToAction = [pullUpView frame].origin.y + [pullUpView frame].size.height - [scrollView bounds].size.height;

    if ([scrollView contentOffset].y >= thresholdToAction) {
        if (!performingAction) {

            [pullUpView startLoading];

            [UIView beginAnimations:nil context:NULL];
            [UIView setAnimationDuration:0.5];
            [tableView setContentInset:UIEdgeInsetsMake(0, 0, [pullUpView frame].size.height, 0)];
            [UIView commitAnimations];

            /* do your things here */
            performingAction = YES;
        }
    }
}

最后还原tableView的contentInset以隐藏pullUpView.