UITableView is a subclass of UIScrollView, so you can also use:
[mainTableView scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:YES];
Or
[mainTableView setContentOffset:CGPointZero animated:YES];
And in Swift:
mainTableView.setContentOffset(CGPointZero, animated:true)
And in Swift 3 & above:
mainTableView.setContentOffset(.zero, animated: true)
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