How to deal with safeAreas

[teejayhh]

I have an issue in regards to safeAreas specifically with the notch on iPhones. We don't use any storyboards or visual layout tech Xcode offers. All our layout is done in code and it works great for sims and real devices. One issue we are having with snapshots is that it does not respect the window safeAreaInset property which is set for every device.

We ve code to align a logo to top of the screen. That is of cause different from device to device.

    if let window = UIApplication.shared.mainKeyWindow {
            self.top = window.safeAreaInsets.top >= top ? window.safeAreaInsets.top + top : top
            self.left = window.safeAreaInsets.bottom >= left ? window.safeAreaInsets.left + left : left
            self.bottom = window.safeAreaInsets.bottom >= bottom ? window.safeAreaInsets.bottom + bottom : bottom
            self.right = window.safeAreaInsets.right >= right ? window.safeAreaInsets.right + right : right
    }

    func test_snapshot_welcomePage_slide_six_largePhone() {
        let welcomeViewController = makeSutForDevice(UXDeviceAUProMaxPhone())
        welcomeViewController.gotoPage = 5
        assertSnapshot(matching: welcomeViewController, as: .image(on: .iPhone12ProMax(.portrait), precision: precision))
     }

The test renders fine but our header is glued to top of the frame where it should sit further down due to the notch. So for some reason the safeAreaInset is set to .zero.

I looked into the code and I can say that removeTopInset is false!

private final class Window: UIWindow {
.....
@available(iOS 11.0, *)
  override var safeAreaInsets: UIEdgeInsets {
    #if os(iOS)
    let removeTopInset = self.config.safeArea == .init(top: 20, left: 0, bottom: 0, right: 0)
      && self.rootViewController?.prefersStatusBarHidden ?? false
    if removeTopInset { return .zero }
    #endif
    return self.config.safeArea
  }
}

So I guess

UIApplication.shared.mainKeyWindow (what I use to get the inset for my constraints) is zero because its the saveInset of the device the app is running in (iPad9)

So it is not the correct Window class with the config insets applied. How can I fix this?

[teejayhh]

After looking at the code a bit more, its very clear that UIApplication.shared.mainKeyWindow would never return the correct UIWindow instance.

[teejayhh]

in order to layout my view components with the correct safeareas I could use the views window property. There is one catch though. The ViewControllers view sets the window property after viewDidLoad has finished and therefor is always nil in snapshot tests. The window property is only set after viewDidAppear was called.

[teejayhh]

I have opted to pass in the the Window safe areas to the controller during tests, and let it layout normally when the property is nil. Its very hacky bit it works for me now.