UITableView的scrollToRowAtIndexPath:atScrollPosition:animated的崩溃

来源：互联网发布：怎么解锁windows驱动器编辑：程序博客网时间：2024/06/06 14:10

reason: '-[UITableView _contentOffsetForScrollingToRowAtIndexPath:atScrollPosition:]: row (0) beyond bounds (0) for section (0).

这个错误是传入的IndexPath已经越界了。需要在调用之前加入判断语句，不影响性能的情况下，在调用之前要先reloadDate

代码示例：

- (void)scrollToBottomAnimated:(BOOL)animated

{    if ([_messageList count] > 0 ) {        NSInteger lastSectionIndex = [self.tableView numberOfSections] - 1;        NSInteger lastRowIndex = [self.tableView numberOfRowsInSection:lastSectionIndex] - 1;        if (lastSectionIndex > 0 && lastRowIndex > 0) {            NSIndexPath *lastIndexPath = [NSIndexPath indexPathForRow:lastRowIndex inSection:lastSectionIndex];            [self.tableView scrollToRowAtIndexPath:lastIndexPath atScrollPosition: UITableViewScrollPositionBottom animated:animated];        }    }}

Update:

上面的代码有BUG，当section = 1时，永远不会滚动。当section = 0时，

[self.tableView numberOfRowsInSection:lastSectionIndex]

会有崩溃，正确代码段：

@implementation UITableView (ScrollToTopOrBottom)- (void)scrollToTopWithAnimated:(BOOL)animated{    if ([self numberOfSections] > 0 && [self numberOfRowsInSection:0] > 0) {        [self scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:animated];    }}- (void)scrollToBottomWithAnimated:(BOOL)animated{    if ([self numberOfSections] > 0) {        NSInteger lastSectionIndex = [self numberOfSections] - 1;        NSInteger lastRowIndex = [self numberOfRowsInSection:lastSectionIndex] - 1;        if (lastRowIndex > 0) {            NSIndexPath *lastIndexPath = [NSIndexPath indexPathForRow:lastRowIndex inSection:lastSectionIndex];            [self scrollToRowAtIndexPath:lastIndexPath atScrollPosition: UITableViewScrollPositionBottom animated:animated];        }    }}@end

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