UIPopoverPresentationController 使用

- (void)addVehBtnClick:(UIButton *)btn{
    GOCarsMenueViewController *vc = [[GOCarsMenueViewController alloc] init];
    vc.modalPresentationStyle = UIModalPresentationPopover;
    vc.preferredContentSize = CGSizeMake(kScreenWidth * 0.4, 100);
    UIPopoverPresentationController *pover = vc.popoverPresentationController;
    [pover setSourceRect:btn.frame];
    [pover setSourceView:btn];
    pover.delegate = self;
    [self presentViewController:vc animated:YES completion:nil];
}

- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController:(UIPresentationController *)controller {
    return UIModalPresentationNone;
}