Swift:防止ABPeoplePickerNavigationController关闭

我想找出一种方法,如果用户在 ABPeoplePickerNavigationController ,视图控制器要么不关闭,要么将自动重新打开。

例如,给定以下内容:

var picker = ABPeoplePickerNavigationController()
picker.peoplePickerDelegate = self
self.presentViewController(picker, animated: true, completion: nil)

我希望能够做到以下几点:

if (self.presentedViewController != picker && !userContinuedPastPicker) {
//where userContinuedPastPicker is a boolean set to false 
//in a delegate method called when the user clicks on an a contact 
//(meaning the user didn't press the cancel button but instead clicked on a contact)

    //create and present a UIAlertAction informing the user they must select a contact

    //present picker again
    self.presentViewController(picker, animated: true, completion: nil) 
}

这行不通;然而,因为 if 语句不会“等待”,直到用户按下取消按钮或按下联系人。