Obj-c - 滑动以删除 tableview 行？

Question

I'm having the strangest issue. I'm using the below code to allow my user to swipe over a row in my tableview, have it reveal the delete button, and upon tapping delete, the row should disappear. That said, this all seems to work when I remove the animation line, but this one line is crashing my app:

 [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationLeft];

Of course, I need the animation in order to visually represent the removal of the row.

The error I get is:

*** Assertion failure in -[UITableView _Bug_Detected_In_Client_Of_UITableView_Invalid_Number_Of_Rows_In_Section:], UITableView.m:2435 2021-02-03 18:06:50.543199-0800 Docket[28322:1330031] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'

ViewController.m

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    
   if (tableView == self.todaytableView) {
        
        NSLog(@"DELETING");
        
    return YES;
        
  }
    
    return NO;
}


- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath{
    
    if (tableView == self.todaytableView) {
        
        return UITableViewCellEditingStyleDelete;
        
    }
    
    return NO;
}

- (BOOL)tableView:(UITableView *)tableview shouldIndentWhileEditingRowAtIndexPath:(NSIndexPath *)indexPath {
    return YES;
}

    - (void)tableView:(UITableView *)tableView commitEditingStyle: (UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
     
        if (tableView == self.todaytableView) {
            
        if (editingStyle == UITableViewCellEditingStyleDelete) {
          
            [self.finalTimes removeObjectAtIndex:indexPath.row];
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationLeft];
    
            
         }
            
        }
    
    }

Answer 1

first add this

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    return YES;
}

then

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        //remove the deleted object from your data source.
        //If your data source is an NSMutableArray, do this
        [self.dataArray removeObjectAtIndex:indexPath.row];
        [tableView reloadData]; // tell table to refresh now
    }
}

Answer 2

You could try wrapping your updates in beginUpdates and endUpdates (they must be paired), as below:

- (void)tableView:(UITableView *)tableView 
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle 
forRowAtIndexPath:(NSIndexPath *)indexPath {
 
    if (tableView == self.todaytableView) {
        
        if (editingStyle == UITableViewCellEditingStyleDelete) {

            [self.finalTimes removeObjectAtIndex:indexPath.row];

            [tableView beginUpdates];
            [tableView deleteRowsAtIndexPaths:@[indexPath]
                             withRowAnimation:UITableViewRowAnimationLeft];
            [tableView endUpdates];
        }
    }
}

I don't think that is what causes the assert failure though. You may want to double check that your

- (NSInteger)tableView:(UITableView *)tableView
 numberOfRowsInSection:(NSInteger)section

method is returning the correct value after altering the dataSource for your table, since it looks like that is the specific thing the error mentions. If the value returned by this method doesn't match the number rows you had in the first place minus the number of rows you just removed from your table, then the assert will fail.

I did see that you had

[self.finalTimes removeObjectAtIndex:indexPath.row];

so it's possible you're already handling that, but I didn't want to assume anything about what was going on in tableView:numberOfRowsInSection: