UIAlertController + addTextField orientation issue from iOS10 on iPad

问题

When I use UIAlertController with addTextField on iPad, the keyboard doesn't rotate properly from iOS10.

It was working fine with iOS9, does anybody know the way to fix it?

UIAlertController *alert =   [UIAlertController
                              alertControllerWithTitle:@"title"
                              message:nil
                              preferredStyle:UIAlertControllerStyleAlert];

UIAlertAction *done = [UIAlertAction actionWithTitle:NSLocalizedString(@"Done", nil)
                                               style:UIAlertActionStyleDefault
                                             handler:^(UIAlertAction * action) {

                                                 UITextField *textField = alert.textFields.firstObject;
                                             }];

UIAlertAction *cancel = [UIAlertAction actionWithTitle:NSLocalizedString(@"Cancel", nil)
                                                 style:UIAlertActionStyleCancel
                                               handler:nil];

[alert addAction:cancel];
[alert addAction:done];

[alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
}];

[self presentViewController:alert animated:YES completion:nil];

来源：https://stackoverflow.com/questions/40318488/uialertcontroller-addtextfield-orientation-issue-from-ios10-on-ipad