UITableView does not automatically deselect the selected row when the table re-appears

When your main ViewController is from type UITableViewController, it has a property clearsSelectionOnViewWillAppear, which is per default YES - so it will clear the selection automatically.

This property is not available for an UITableView, i guess it's because it has no ViewWillAppear method either.

A UIViewController doesn't need this property because it has no UITableView originally.

conclusion: you'll have to implement it by yourself when you do not use a UITableViewController.

Do the deselection in didSelectRowAtIndexPath instead of viewWillAppear:

- (void)tableView:(UITableView *)tableView
                  didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
     //show the second view..
     [tableView deselectRowAtIndexPath:indexPath animated:YES]; 
 }

In swift, you can add the following lines in your viewWillAppear

if let row = tableView.indexPathForSelectedRow() {
    tableView.deselectRowAtIndexPath(row, animated: true)
}

In swift 2, it's without parantheses:

if let row = tableView.indexPathForSelectedRow {
    tableView.deselectRowAtIndexPath(row, animated: true)
}

In Swift 4 (and 3?) the function name was cleaned up:

if let indexPath = tableView.indexPathForSelectedRow {
    tableView.deselectRow(at: indexPath, animated: true)
}