Removing backgrounds from a NavigationSplitView

[slaght]

Hey all,

Firstly wanted to say thanks for your work on the library, it's proven super useful so far.

I'm using SwiftUIIntrospect 0.8.0 on an iOS 17 project to try to remove the background from a NavigationSplitView (I am displaying a view underneath it and want it to persist throughout the application). The following code is working for removing the backgrounds initially:

...
NavigationSplitView(columnVisibility: NavigationSplitViewVisibility.detailOnly) {
	List(menuItems, selection: $selectedItem) { item in
		Text(item.name)
	}
} detail: {
	TestView()
}
.introspect(.navigationSplitView, on: .iOS(.v17)) {
	$0.viewControllers.forEach { controller in
		controller.parent?.view.backgroundColor = .clear
		clearBackgrounds(view: controller.view)
	}
}
...

func clearBackgrounds(view: UIView) {
	view.backgroundColor = .clear
	for subview in view.subviews {
		clearBackgrounds(view: subview)
	}
}

This works beautifully... until a detail view gets presented when clicking on a list item. When this happens it appears that the backgrounds reappear:

How do I introspect the detail views to remove their backgrounds as well? I have tried introspecting NavigationSplitView in the TestView instance in the detail declaration but that doesn't seem to do anything.

[davdroman]

Thanks for your question, @slaght.

Indeed, setting backgroundColors via introspection is flakey. SwiftUI insists on overriding the background color of its UIKit components on each state update. However, I'm not convinced this is necessarily a problem begging for introspection, as nowadays SwiftUI offers modifiers to clear out a number of backgrounds. Instead, a hybrid approach might be best.

Here's what I came up with:

https://github.com/davdroman/NavigationSplitViewRemoveBackgrounds

Note I took the liberty to drop in a .navigationTransition(.slide) modifier from my https://github.com/davdroman/swiftui-navigation-transitions library to make the transition smoother, because the default iOS transition looks quite weird with transparent backgrounds on.

Let me know what you think.

[slaght]

Wow, thanks for taking the time to create an entire sample project, this works perfectly. Managed to adapt it to my project and make it a little more versatile by checking for and ignoring views of certain types (ex. ListCollectionViewCell) that should maintain their backgrounds. Will also be taking a look at your navigation transition library because I can see the wonky transition effects you mentioned.