Accessing system colors in WatchKit - uikit

Question

I am trying to use UIKit colors for my Apple Watch interface. You can do it in iOS with UIColor class properties like .systemBackground and others. For example:
let myColor = UIColor.systemBlue
Gives me error when compiling watchOS extension target:
Type 'UIColor' has no member 'UIColor.systemBlue'.
I wonder tis there alternative way to get this system colors, and if not — what I need is to get a color of some UI elements, like SwiftUI table view row background which looks very similar to UIColor.systemGray5.
#State private var isActive = false
var body: some View {
List {
Section() {
ForEach(self.dataSource) { item in
CustomCell()
.listRowPlatterColor(self.isActive ? Color(UIColor.systemGray5) : Color(.orange))
}
}
}
}
Code above won't compile because UIColor.systemGray5 is not found in WatchKit. I have tried to create a class which is sued both in iPhone and Watch target and it fixes Xcode autocompletion. But the app breaks when trying to use it the Apple Watch target.
I hope there's a way rather then finding correct color and hard-coding it.

Answer 1

Looking at the documentation, the UIColor.system-ish are only available for iOS, Catalyst and some for tvOS. What you can do is extend UIColor and create you systemGray5:
extension UIColor {
static var mySystemGray5: UIColor {
return .init(red: 229/255, green: 229/255, blue: 234/255, alpha: 1)
}
}
And use on your code like:
ForEach(self.dataSource) { item in
CustomCell()
.listRowPlatterColor(self.isActive ? Color(UIColor.mySystemGray5) : Color(.orange))
}

Answer 2

Since you are using SwiftUI, Color.blue is equivalent to UIColor.systemBlue.
Unfortunately, Color doesn't have a lots of UIColor system colors, hopefully Apple add missing colors on WWDC 2020.
May be use can use something like Color.gray.opacity.opacity(0.25) in the meanwhile?