SwiftUI - Add a Navigation Bar Button on Condition

Question

Given i have a view like this..

@State var tabIndex: Int = 0
           
 var body: some View {

  TabView(selection: $tabIndex)
  {
   Text("Tab 1").tabItem({
    Image(systemName: "message")
   }).tag(0)           
                
   Text("Tab 2").tabItem({
    Image(systemName: "arkit")
   }).tag(1)             
          
   Text("Tab 3").tabItem({
    Image(systemName: "battery.100")
   }).tag(2)
  }.navigationBarTitle("Tabbed View")
            
 }

This produces a view like this which is what is expected:

to add a navigation button to the bar i can use

 .navigationBarItems(trailing:
  Button(action: {print("Button was tapped")}) {
   Image(systemName: "plus")
    .resizable().frame(width: 20, height: 20)
  })

Which adds the button as expected

Is there any way to only add (or show) the button based on a condition?

if (self.tabIndex == 1){
  show button
}
else {
 don't show button
}

TabView embedded inside NavigationView isn't a good choice. Instead every tab in the TabView should have its own NavigationView. Like if there are three tabs, there should be three NavigationView if every tab needs their navigation hierarchy. — nayem
– nayem, Commented Jan 3, 2020 at 9:20

saltwat5r · Accepted Answer · 2021-10-22 13:10:51Z

22

As .navigationBarItems will be deprecated in a future version of iOS it's better to use .toolbar(_:) View Modifier.

.toolbar {
    ToolbarItemGroup(placement: .navigationBarTrailing) {
        if tabIndex == 2 {
            // show button
        }
    }
}

answered Oct 22, 2021 at 13:10

saltwat5r

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3 Comments

inreflection7 Over a year ago

This should be the new accepted answer

Abhinav Mathur Over a year ago

No need to use AnyView as well

aehlke Over a year ago

navigationBarTrailing isn't defined for me

Martijn Pieters · Accepted Answer · 2022-08-23 07:12:09Z

17

Here is possible approach

.navigationBarItems(trailing: self.tabIndex == 1 ? 
    AnyView(self.trailingButton) : AnyView(EmptyView()))

somewhere below body

var trailingButton: some View {
  Button(action: {print("Button was tapped")}) {
   Image(systemName: "plus")
    .resizable().frame(width: 20, height: 20)
  }
}

edited Aug 23, 2022 at 7:12

Martijn Pieters

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answered Jan 3, 2020 at 9:24

Asperi

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1 Comment

Rillieux Over a year ago

I'm curious why you don't just put the button on the relevant view under it's tab? Is there a reason it needs to be on the TabView?

user12208004 · Accepted Answer · 2020-09-05 13:26:29Z

5

If you don't want to use AnyView, you could also use Group or Opacity too.

.navigationBarItems(trailing: Group {
  if self.tabIndex == 1 {
    Button(action: {print("Button was tapped")}) {
     Image(systemName: "plus")
      .resizable().frame(width: 20, height: 20)
    }
  }
})

.navigationBarItems(trailing: 
    Button(action: {print("Button was tapped")}) {
     Image(systemName: "plus")
      .resizable().frame(width: 20, height: 20)
    }.opacity(self.tabIndex == 1 ? 1 : 0)
)

answered Sep 5, 2020 at 13:26

user12208004

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Comments

Chucky · Accepted Answer · 2020-09-24 22:26:44Z

3

I know this question has an accepted answer and I used it in my own solution but here's what I did:

var doneButton:AnyView {
    if !fromPreferences {
        return AnyView(Button(action: self.doneAction) {
            Text("Done")
        })
    }
    return AnyView(EmptyView())
}

and how I used it in the body:

.navigationBarItems(trailing: doneButton)

thanks @Asperi for the solution!

answered Sep 24, 2020 at 22:26

Chucky

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Comments

Cloud · Accepted Answer · 2020-07-14 19:19:45Z

1

Here is what worked for me, even when my condition was false which resulted in nothing being returned (the bar item correctly did not show, without errors). I find it a little cleaner than squeezing in a ternary operator.

.navigationBarItems(
    trailing: Button(
        action: {
            print("My Action")
        }
    ) {
        if myBool {
            Text("My Button")
        }
    }
)

answered Jul 14, 2020 at 19:19

Cloud

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