在 iPad 上展示视图控制器只允许 .Popover

Question

I have an iPhone application that I am trying to make universal. I have this code:

let documentMenu = UIDocumentMenuViewController(documentTypes: [kUTTypeContent as String], inMode: .Import)
documentMenu.modalPresentationStyle = .FormSheet
documentMenu.delegate = self
self.presentationContext.presentViewController(documentMenu, animated: true, completion: nil)

self.presentationContext is just a view controller passed into the class.

Every time this code is executed, this error occurs:

Your application has presented a UIDocumentMenuViewController (). In its current trait environment, the modalPresentationStyle of a UIDocumentMenuViewController with this style is UIModalPresentationPopover. You must provide location information for this popover through the view controller's popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem. If this information is not known when you present the view controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.

I am not sure what's going on. I have even tried to set the sourceView and sourceRect , to which does stop the error, however, it sticks the DocumentMenuViewController into a popover, I do not what that. I need this modally presented in the center of the screen. Any help is appreciated.

Answer 1

Following code is working fine

let importMenu = UIDocumentMenuViewController(documentTypes: [String(kUTTypePDF)], in: .import)

    importMenu.popoverPresentationController?.sourceView = self.view // so that iPads won't crash

    importMenu.delegate = self
    importMenu.modalPresentationStyle = .formSheet
    self.present(importMenu, animated: true, completion: nil)

Answer 2

The issue is that UIDocumentMenuViewController doesn't want to be displayed as anything other than a smaller, "popover" presentation style. Its own implementation overrides any setting of its modalPresentationStyle to .Popover . So your attempt to set the style to .FormSheet is ultimately ignored.

This is what causes the error. Once the style is .Popover , you must do what the error states and set some appropriate combination of sourceView and sourceRect or barButtonItem .

File an enhancement request with Apple to allow support for other modal presentation styles. In the meantime, you need to adjust your UI.

Answer 3

let documentMenu = UIDocumentMenuViewController(documentTypes: [kUTTypeContent as String], inMode: .Import)
documentMenu.popoverPresentationController?.sourceView = self // UIView 
documentMenu.modalPresentationStyle = .popover
documentMenu.delegate = self
self.presentationContext.presentViewController(documentMenu, animated: true, completion: nil)

Answer 4

my two cents for Mac Catalyst:

on Mac Catalyst you must use .formSheet

so:

   #if targetEnvironment(macCatalyst)
    let modalPresentationStyle : UIModalPresentationStyle = .formSheet
    #else
    let modalPresentationStyle : UIModalPresentationStyle = .popover
    #endif

    optionsVC.modalPresentationStyle = modalPresentationStyle
    optionsVC.popoverPresentationController?.sourceView = self.view

    self.present(optionsVC, animated: true) {
    }

eventually add:

optionsVC.modalPresentationStyle = modalPresentationStyle

to prevent tapping outside will close without invoking callbacks (iOs13 / Catalyst only)