Q:

iCLoud document picker from WKWebview dismissing container view

I have a WKWebview loading a web based UI where I would like users to be able to upload a file from their iCloud documents. I have granted the correct permissions and I am able to browse the iCloud documents. However when I either select a file or click the cancel button, as well as the document picker view dismissing the parent view of my WKWebview is also dismissed.
I have tried to track the dismiss path. I am 100% sure I am not calling the dismiss function on my view.
Does anyone have any idea what is triggering the dismiss on my WKWebview container and how to prevent it? 

A:

There is a bug in UIDocumentPickerViewController.
1) Save weak reference to UIDocumentPickerViewController inside what ever view controller presents the UIDocumentPickerViewController. (This usually end up being a UINavigationController so you will probably have to subclass UINavigationController to fix this.)
///Due to a bug in UIDocumentPickerViewController we need to stop the UIDocumentPickerViewController from dismissing this navigation controller. Or at least provide control. This is a weak reference to a UIDocumentPickerController that this controller presents
weak var documentPicker: UIDocumentPickerViewController?

2) Override these two functions on the UIViewController that is presenting the UIDocumentPickerViewController
//MARK: Overrides
override public func dismiss(animated flag: Bool, completion: (() -> Void)? = nil) {
    if self.presentedViewController == nil && self.documentPicker != nil {
        self.documentPicker = nil
    }else{
        super.dismiss(animated: flag, completion: completion)
    }
}

public override func present(_ viewControllerToPresent: UIViewController, animated flag: Bool, completion: (() -> Void)? = nil) {
    if viewControllerToPresent is UIDocumentPickerViewController {
        self.documentPicker = viewControllerToPresent as? UIDocumentPickerViewController
    }
    super.present(viewControllerToPresent, animated: flag, completion: completion)
}

Now the second call from the UIDocumentPickerViewController will not dismiss the presenting UIViewController.

A:

I had the same problem on Objective-C and iOS11 with WKWebView and solved it using this workaround. You should be able to migrate it to Swift easily :

my WKWebView was owned by a view controller directly extending UIViewController
inside this view controller add this weak property
@property (weak, nonatomic) UIDocumentPickerViewController *_Nullable docPickerPtr;
inside same view controller override these two methods originally part of the UIViewController base class
- (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^ __nullable)(void))completion
{
    if ([viewControllerToPresent isKindOfClass:[UIDocumentPickerViewController class]])
    {
        _docPickerPtr = (UIDocumentPickerViewController*)viewControllerToPresent;
    }

    [super presentViewController:viewControllerToPresent animated:flag completion:completion];
}

- (void)dismissViewControllerAnimated:(BOOL)flag
                           completion:(void (^)(void))completion
{
    if (_docPickerPtr != nil && self.presentedViewController == nil)
    {
        NSLog(@">>>>>>>>>>>>PREVENT FROM DOING 2nd DISMISS!");
    }
    else
    {    
        [super dismissViewControllerAnimated:flag completion:completion];
    }
}

what we do is :

when we're about to display the document picker, save a weak pointer to the UIDocumentPickerViewController  
the dismissViewControllerAnimated:completition gets called twice. Once while the presentedViewController is not nil yet to kill the actual document picker, and a 2nd time for unknown reasons when presentedViewController is gone but UIDocumentPickerViewController is still alive. The idea is to prevent this 2nd dismiss propagate to super

