MyViewController *viewController = [[MyViewController alloc] init];
viewController.modalPresentationStyle = UIModalPresentationPopover;
emptyViewController.preferredContentSize = CGSizeMake(300, 200);
UIPopoverPresentationController *pop = emptyViewController.popoverPresentationController;
pop.sourceRect = CGRectMake(10, 10, 20, 20);
pop.sourceView = self.view;
pop.delegate = self;
[self.navigationController presentViewController:emptyViewController animated:YES completion:nil];
如果想在 iPhone 上也显示为非全屏的弹出框，需要实现 UIPopoverPresentationControllerDelegate 协议的方法，返回 UIModalPresentationNone 即可：
- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController:(UIPresentationController *)controller {
return UIModalPresentationNone;
}
