UITableView scrollToRowAtIndexPath

问题描述

我正在尝试让我的表格视图记住它的最后位置，以便在应用程序再次运行后，它将滚动到该位置。要做到这一点，在我的 viewWillDisappear：方法中，我得到第一个可见的行号并将其保存到 NSUserDefaults 。然后在我的viewDidAppear中，我尝试通过向表视图发送 scrollToRowAtIndexPath 来滚动到该行。但是我得到 NSRangeException ：

I'm trying to make my table view remember it's last position, so that after the app is run again, it will scroll to that position. to do this, in my viewWillDisappear: method, I get the first visible row number and save it to NSUserDefaults. then in my viewDidAppear I try to scroll to that row by sending scrollToRowAtIndexPath to the table view. However I get a NSRangeException:

任何帮助表示赞赏。以下是代码：

any help appreciated. Here is the code:

- (void)viewDidAppear:(BOOL)animated
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

    if ([userDefaults valueForKey:@"content_row"] != nil)
    {
        int rowToHighlight = [[userDefaults valueForKey:@"content_row"] intValue];
        NSIndexPath * ndxPath= [NSIndexPath indexPathForRow:rowToHighlight inSection:0];
        [contentTableView scrollToRowAtIndexPath:ndxPath atScrollPosition:UITableViewScrollPositionTop  animated:YES];
    }
}

-(void) viewWillDisappear:(BOOL)animated
{
    NSIndexPath *selectedRowPath = [[contentTableView indexPathsForVisibleRows] objectAtIndex:0];
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setInteger:selectedRowPath.row forKey:@"content_row"];
}

推荐答案

在调用scrollToRowAtIndexPath之前重新加载TableView数据。

Reload TableView data before calling scrollToRowAtIndexPath.

[contentTableView reloadData];

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