iOS 如何在已经堆叠的 ViewController 上调用 presentViewController

Question

我正在尝试将 View Controller 推送到已经推送的 View Controller 上，如下所示。然而，不知何故，当我尝试推送 newPersonViewController 时，这个新 Controller 并没有被推送到堆栈上。我不知道为什么 Xcode 提示我试图添加一个不属于层次结构的新 Controller 。我是否错误地呈现了 ABPeoplePickerViewController？这就是 newPersonViewController 无法被压入堆栈的原因吗？

来自控制台的消息:

Warning: Attempt to present on whose view is not in the window hierarchy!

代码:

- (void)addPerson
{
    ABNewPersonViewController *newPersonVC = [[ABNewPersonViewController alloc] init];
    newPersonVC.newPersonViewDelegate = self;
    UINavigationController *uiNav = [[UINavigationController alloc] initWithRootViewController:newPersonVC];

    [self presentViewController:uiNav animated:YES completion:nil];
}

- (void)showPeoplePicker
{
    ABPeoplePickerNavigationController *picker = [[ABPeoplePickerNavigationController alloc] init];
    picker.peoplePickerDelegate = self;

    [self presentViewController:picker animated:YES completion:nil];
    [picker.topViewController setEditing:YES];
    picker.topViewController.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addPerson)];
    picker.topViewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel target:self action:@selector(peoplePickerCancel)];
}

Answer 1

问题是 addPerson 试图从不是当前 Controller 的 View Controller 中以模态方式呈现。 self(您的原始 View Controller )不是事件 Controller 。 ABPeoplePickerNavigationController 是。

因此，首先，定义一个类属性来跟踪picker:

@property (nonatomic, weak) ABPeoplePickerNavigationController *picker;

然后，

• 修改 showPeoplePicker 以设置该属性；和
• 修改 addPerson 以使用该属性:

因此:

- (void)addPerson
{
    ABNewPersonViewController *newPersonVC = [[ABNewPersonViewController alloc] init];
    newPersonVC.newPersonViewDelegate = self;
    UINavigationController *uiNav = [[UINavigationController alloc] initWithRootViewController:newPersonVC];

    [self.picker presentViewController:uiNav animated:YES completion:nil];
}

- (void)showPeoplePicker
{
    ABPeoplePickerNavigationController *picker = [[ABPeoplePickerNavigationController alloc] init];
    picker.peoplePickerDelegate = self;

    [self presentViewController:picker animated:YES completion:nil];
    [picker.topViewController setEditing:YES];
    picker.topViewController.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd    target:self action:@selector(addPerson)];
    picker.topViewController.navigationItem.leftBarButtonItem  = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel target:self action:@selector(peoplePickerCancel)];

    self.picker = picker;
}

- (void)newPersonViewController:(ABNewPersonViewController *)newPersonView didCompleteWithNewPerson:(ABRecordRef)person
{
    [newPersonView dismissViewControllerAnimated:YES completion:nil];
}