ios - 将行添加到不带动画的表格 View 的开头

Question

我想用begin/endUpdates向tableview添加行，以防止reloadData时tableview跳转

这是我的代码

- (void)updateTableWithNewRowCount:(NSInteger)rowCount
                        andNewData:(NSArray *)newData {
  // Save the tableview content offset
  CGPoint tableViewOffset = [self.messagesTableView contentOffset];

  // Turn of animations for the update block
  // to get the effect of adding rows on top of TableView
  [UIView setAnimationsEnabled:NO];

  [self.messagesTableView beginUpdates];

  NSMutableArray *rowsInsertIndexPath = [[NSMutableArray alloc] init];

  int heightForNewRows = 0;

  for (NSInteger i = 0; i < rowCount; i++) {

    NSIndexPath *tempIndexPath = [NSIndexPath indexPathForRow:i inSection:0];
    [rowsInsertIndexPath addObject:tempIndexPath];
//    [self.messages insertObject:[newData objectAtIndex:i] atIndex:i];
      [self addMessage:[newData objectAtIndex:i]];

    heightForNewRows =
        heightForNewRows + [self heightForCellAtIndexPath:tempIndexPath];
  }

  [self.messagesTableView insertRowsAtIndexPaths:rowsInsertIndexPath
                                withRowAnimation:UITableViewRowAnimationNone];

  tableViewOffset.y += heightForNewRows;

  [self.messagesTableView endUpdates];

  [UIView setAnimationsEnabled:YES];

  [self.messagesTableView setContentOffset:tableViewOffset animated:NO];
}

有时(不是每次)我都会收到此错误

 invalid number of rows in section 0.
 The number of rows contained in an existing section after
 the update (2) must be equal to the number of rows contained in that section
 before the update (2), plus or minus the number of rows inserted or deleted
 from that section (2 inserted, 0 deleted) and plus or minus the number of
 rows moved into or out of that section (0 moved in, 0 moved  out).

如何防止此错误？

Answer 1

如果你不需要动画那就直接使用

- (void)updateTableWithNewRowCount:(NSInteger)rowCount
                        andNewData:(NSArray *)newData {
  // Save the tableview content offset
  CGPoint tableViewOffset = [self.messagesTableView contentOffset];

  // Turn of animations for the update block
  // to get the effect of adding rows on top of TableView

  NSMutableArray *rowsInsertIndexPath = [[NSMutableArray alloc] init];

  int heightForNewRows = 0;

  for (NSInteger i = 0; i < rowCount; i++) {

    NSIndexPath *tempIndexPath = [NSIndexPath indexPathForRow:i inSection:0];
    [rowsInsertIndexPath addObject:tempIndexPath];
//    [self.messages insertObject:[newData objectAtIndex:i] atIndex:i];
      [self addMessage:[newData objectAtIndex:i]];

    heightForNewRows =
        heightForNewRows + [self heightForCellAtIndexPath:tempIndexPath];
  }

  tableViewOffset.y += heightForNewRows;

  [self.messagesTableView reloadData];

  [self.messagesTableView setContentOffset:tableViewOffset animated:NO];
}