问题
I am trying to see if I can make the color of the bottom tabview change depending on which tab item is selected. Currently I can make the tabview bar clear with the below code in the init.
let tabBar = UITabBar.appearance()
init() {
tabBar.barTintColor = UIColor.clear
tabBar.backgroundImage = UIImage()
tabBar.shadowImage = UIImage()
}
...
TabView(selection: $selectedTab) {
FirstView()
.tabItem{
Text("First")
}
SecondView()
.tabItem{
Text("Second")
}
}
.onAppear{
setTabViewBackground()
}
func setTabViewBackground() {
if selectedTab != 0 {
tabBar.barTintColor = UIColor.blue
}
}
Tried to just fire the func when the body redraws and idk if its this declarative style that's getting the best of me but doesn't change the tabview background at all.
回答1:
Any .appearance
affects instances created after the appearance itself. So the solution is to re-create TabView
after appearance configuration changed.
Here is a demo of approach. Tested with Xcode 12 / iOS 14.
struct DemoView: View {
let tabBar = UITabBar.appearance()
init() {
tabBar.barTintColor = UIColor.red
}
@State private var selectedTab = 0 // preserves selected tab
var body: some View {
TabView(selection: $selectedTab) {
Text("FirstView")
.tabItem{
Text("First")
}.tag(0)
Text("SecondView")
.tabItem{
Text("Second")
}.tag(1)
}
.onAppear {
setTabViewBackground() // called, because `id` is below
}
.id(selectedTab) // recreates entire above view with new tabbar
}
func setTabViewBackground() {
tabBar.barTintColor = selectedTab != 0 ? .blue : .red
}
}
来源:https://stackoverflow.com/questions/63404238/change-tabview-color-based-on-which-tab-is-selected-swiftui