iOS 8 presentationController确定是否真的是popover [英] iOS 8 presentationController determine if really is popover

问题描述

我正在使用iOS 8的新自适应Present As Popover功能。我在StoryBoard中连接了一个简单的segue来进行演示。它在iPhone 6 Plus上运行良好，因为它将视图显示为弹出窗口，在iPhone 4s上显示为全屏视图（工作表样式）。

I'm using the new adaptive "Present As Popover" capability of iOS 8. I wired up a simple segue in the StoryBoard to do the presentation. It works great on an iPhone 6 Plus as it presents the view as a popover and on an iPhone 4s it shows as a full screen view (sheet style).

问题当显示为全屏视图时，我需要在视图中添加完成按钮，以便可以调用dismissViewControllerAnimated。当它显示为弹出窗口时，我不想显示完成按钮。

The problem is when shown as a full screen view, I need to add a "Done" button to the view so dismissViewControllerAnimated can be called. And I don't want to show the "done" button when it's shown as a popover.

我试着查看presentationController和popoverPresentationController的属性，我什么都没找到，告诉我如果它实际上显示为弹出框。

I tried looking at the properties of both presentationController and popoverPresentationController, and I can find nothing that tells me if it is actually being shown as a popover.

NSLog( @"View loaded %lx", (long)self.presentationController.adaptivePresentationStyle );          // UIModalPresentationFullScreen
NSLog( @"View loaded %lx", (long)self.presentationController.presentationStyle );                  // UIModalPresentationPopover
NSLog( @"View loaded %lx", (long)self.popoverPresentationController.adaptivePresentationStyle );   // UIModalPresentationFullScreen
NSLog( @"View loaded %lx", (long)self.popoverPresentationController.presentationStyle );           // UIModalPresentationPopover

adaptivePresentationStyle总是返回UIModalPresentationFullScreen，而presentationStyle总是返回UIModalPresentationPopover

adaptivePresentationStyle always returns UIModalPresentationFullScreen and presentationStyle always returns UIModalPresentationPopover

在查看UITraitCollection时，我发现了一个名为_UITraitNameInteractionModel的特征，当它实际显示为Popover时，它只被设置为1。但是，Apple不提供通过popoverPresentationController的traitCollection直接访问该特征。

When looking at the UITraitCollection I did find a trait called "_UITraitNameInteractionModel" which was only set to 1 when it was actually displayed as a Popover. However, Apple doesn't provide direct access to that trait through the traitCollection of popoverPresentationController.

推荐答案

最好的方式（最不臭）我发现这样做是为了使用 UIPopoverPresentationControllerDelegate 。

The best way (least smelly) I've found to do this is to use the UIPopoverPresentationControllerDelegate.

•确保在 UIPopoverPresentationController上将呈现的视图控制器设置为 UIPopoverPresentationControllerDelegate 用于管理演示文稿。我正在使用故事板，所以在 prepareForSegue中设置：

segue.destinationViewController.popoverPresentationController.delegate = presentedVC;

•在呈现的视图控制器中创建一个属性以跟踪此状态：

• Create a property in the presented view controller to keep track of this state:

@property (nonatomic, assign) BOOL amDisplayedInAPopover;

•添加以下委托方法（或添加到现有的委托方法）：

• And add the following delegate method (or add to your existing delegate method):

- (void)prepareForPopoverPresentation:(UIPopoverPresentationController *)popoverPresentationController
{
    // This method is only called if we are presented in a popover
    self.amDisplayedInAPopover = YES;
}

•最后在 viewWillAppear： - viewDidLoad：太早，在 viewDidLoad：和<$ c之间调用委托prepare方法$ c> viewWillAppear：

• And then finally in viewWillAppear: - viewDidLoad: is too early, the delegate prepare method is called between viewDidLoad: and viewWillAppear:

if (self.amDisplayedInAPopover) {
    // Hide the offending buttons in whatever manner you do so
    self.navigationItem.leftBarButtonItem = nil;
}

编辑：更简单的方法！

只需设置代理（确保您的presentVC采用 UIPopoverPresentationControllerDelegate ）：

Just set the delegate (making sure your presentedVC adopts the UIPopoverPresentationControllerDelegate):

segue.destinationViewController.popoverPresentationController.delegate = presentedVC;

并提供方法：

- (void)prepareForPopoverPresentation:(UIPopoverPresentationController *)popoverPresentationController
{
    // This method is only called if we are presented in a popover
    // Hide the offending buttons in whatever manner you do so
    self.navigationItem.leftBarButtonItem = nil;
}

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