On iOS 15, the UIHostingController is adding some weird extra padding to its hosting SwiftUI view (_UIHostingView)

Question

UPDATE: 2022-09-26

This issue has been fixed on iOS 16. Although the issue is still present on iOS 15 even when the project is compiled with the iOS 16 SDK.

Original question:

On iOS 15, the UIHostingController is adding some weird extra padding to its hosting SwiftUI view (_UIHostingView).

See screenshot below (Blue = extra space, Red = actual view’s):

Does anyone know why this happens?

I've reported this bug, Apple folks: FB9641883

PD: I have a working project reproducing the issue which I attached to the Feedback Assistant issue. If anyone wants it I can upload it too.

score 25 · Accepted Answer · answered Sep 28 '21 at 09:39

25

I found out that subclassing UIHostingController as follows fixes the issue with extra padding:

final class HostingController<Content: View>: UIHostingController<Content> {
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        view.setNeedsUpdateConstraints()
    }
}

It also fixes a problem of the UIHostingController not resizing correctly when its SwiftUI View changes size.

answered Sep 28 '21 at 09:39

Sebastian Osiński

2,894
3
22
34

wow this does work :D Why I didn't think of this one, very smart to try, thanks Sebastian! – Luis Ascorbe Sep 30 '21 at 08:34
I'm trying to create a UIImage from the SwiftUI View and the above still results in a offset/clipped image. – Rob Oct 07 '21 at 13:35
4

This didn’t work for me – Salim Braksa Oct 19 '21 at 11:53
1

It doesn't work if the Content view gets larger. – Daniel Nov 19 '21 at 16:38
1

be sure to add the hosting view controller as a child to the VC as well as a didMove(toParent: self) – strohtennis Mar 21 '22 at 13:26
2

It's never a good idea to modify the view's layout in the viewDidLayoutSubviews, you can easily end up with an infinite loop – Petru Lutenco May 24 '22 at 07:52
This does not work for me – iadcialim24 Feb 08 '23 at 23:17

Luis Ascorbe · Answer 2 · 2021-09-30T08:50:02.447

4

I’ve tried to find why is this happening without luck. The only thing I’ve found to fix it is setting a height constraint to its intrinsic content size in a subclass of UIHostingController:

    private var heightConstraint: NSLayoutConstraint?

    override open func viewDidLoad() {
        super.viewDidLoad()
        if #available(iOS 15.0, *) {
            heightConstraint = view.heightAnchor.constraint(equalToConstant: view.intrinsicContentSize.height)
            NSLayoutConstraint.activate([
                heightConstraint!,
            ])
        }
    }

    override open func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        heightConstraint?.constant = view.intrinsicContentSize.height
    }

edited Sep 30 '21 at 08:50

answered Sep 21 '21 at 08:44

Luis Ascorbe

1,985
1
22
36

2

This one actually worked for me 100%. The accepted answer is flakey in certain situations. – David Roman Apr 06 '22 at 23:31
This does not work for me – iadcialim24 Feb 08 '23 at 23:19

On iOS 15, the UIHostingController is adding some weird extra padding to its hosting SwiftUI view (_UIHostingView)

2 Answers2