UITableView没有窗口iOS13时的UITableViewAlertForLayoutOutsideViewHierarchy

问题描述

我开始在iOS13上收到警告(如下).我注意到此警告弹出是因为 UITableView 的窗口为空(已选择另一个选项卡，在选择表时已推送详细视图控制器...).我正在尝试从 NSFetchedResultController 委托更新 UITableView .在iO13上执行此操作以保持表更新的正确方法是什么?

I started to receive warning (below) on iOS13. I have noticed that this warning pops up because UITableView's window is null (another tab is selected, pushed detailed view controller on table selection...).I am trying to update UITableView from NSFetchedResultController delegate. What is the correct way to do this on iO13 to keep table updated?

下面的代码在以前的版本中工作正常.

Code below worked fine on previous releases.

PS:任何类型的 beginUpdates ， reloadRowsAtIndexPaths:withRowAnimation:， insertSections:withRowAnimation:， endUpdates 导致此警告.

PS: Any kind of beginUpdates , reloadRowsAtIndexPaths:withRowAnimation: , insertSections:withRowAnimation: , endUpdates will cause this warning.

PS:我尝试重新加载表格，但是如果我向后导航，则会丢失动画以取消选择行(清除行选择).

PS: I tried reload table but if I navigate back I lose animation to deselect row (clear row selection).

// ------------  ------------  ------------  ------------  ------------  ------------
#pragma mark - FetchedResultsController delegate

- (void) controllerWillChangeContent:(NSFetchedResultsController *)controller {
//    if (self.tableView.window) {
        [self.tableView beginUpdates];
//    }
}
- (void) controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {

    if (type == NSFetchedResultsChangeInsert && newIndexPath != nil) {
        [self.tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
    }

    if (type == NSFetchedResultsChangeUpdate && indexPath != nil) {
        [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
//        id<CellLoadable> cell = [self.tableView cellForRowAtIndexPath:indexPath];
//        [cell loadData:anObject];
    }

    if (type == NSFetchedResultsChangeMove && indexPath != nil && newIndexPath != nil) {
        // if cell is visible, update it
        id<CellLoadable> cell = [self.tableView cellForRowAtIndexPath:indexPath];
        [cell loadData:anObject];
        [self.tableView moveRowAtIndexPath:indexPath toIndexPath:newIndexPath];
    }
}

- (void) controller:(NSFetchedResultsController *)controller didChangeSection:(id<NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {

    if (type == NSFetchedResultsChangeInsert) {
        [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
    }
    if (type == NSFetchedResultsChangeDelete) {
        [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
    }
}

- (void) controllerDidChangeContent:(NSFetchedResultsController *)controller {
//    if (self.tableView.window) {
        [self.tableView endUpdates];
//    }
}

推荐答案

我发现将表更新包装到在dispatch_async中断点触发的位置可以消除此问题:

I found that wrapping the table update where the breakpoint triggers in dispatch_async eliminates the issue:

dispatch_async(dispatch_get_main_queue(), ^(void){
    [self.table reloadSections:[NSIndexSet indexSetWithIndex:1] withRowAnimation:UITableViewRowAnimationFade];
});

(可能必须走到调用堆栈中才能在中断时找到呼叫)

(may have to walk up the call stack to find the call when it breaks)

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