CODEWITHSUNDEEP
swiftswiftui
Adrian
Adrian

Reputation: 555

NavigationLink calling destination multiple times

While having a NavigationLink set-up like so in Xcode Version 11.4.1 (11E503a):

NavigationView { 
  vm.isShowingBarCharts ? Text("Charts") : Text("List")
}.navigationBarItems(
                NavigationLink(destination: LEditView(vm: LEditViewModel())) {
                    LIcons.addEntry
                        .resizable()
                        .frame(width: 20, height: 20)
                }
)

vm.isShowingBarCharts being a Published of type Bool, the view gets re-drawn (as expected) if vm.isShowingBarCharts gets flipped. What I don't understand is, why multiple LEditViewModel() instances are getting instantiated?

How that can be avoided?

Upvotes: 1

Views: 1752

Answers (2)

Mrugesh Tank
Mrugesh Tank

Reputation: 3560

I was using Timer Publisher which was causing each time redraw view and each second view was being navigated. So, I need to cancel Timer Publisher when the view is about to Navigate to the next view.

viewModel.cancellable?.cancel()

Helps me to solve the issue, where viewModel.cancellable is Combine's Cancellable.

Upvotes: -1

Adrian
Adrian

Reputation: 555

With Xcode 12.1(12A7403) iOS 14.0 + this can be fixed by using the @StateObject property wrapper. If not using @StateObject, the VM will be instantiated every time the parent is re-drawn.

Upvotes: 2

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