onAppear is called when the view hasn't appeared

UI Frameworks SwiftUI
Khuffie
Khuffie OP
Created Aug ’20
Replies 26
Boosts 3
Views 16k
Participants
I'm using a 100% SwiftUI app, currently on Xcode 12 Beta 4

In my ContentView, I have a simple TabView

Code Block swiftstruct ContentView: View {		var body: some View {		TabView {			AgendaView()				.tabItem {					Image(systemName: "list.bullet")					Text("Agenda")				}			HealthView()				.tabItem {					Image(systemName: "heart")					Text("Health")				}		}		}}


The AgendaView and HealthView have onAppear methods. On App launch, the AgendaView is the one visible, but onAppear is called for both AgendaView and HealthView.

Why is that? Shouldn't onAppear be called only when the view actually appears on screen?

Code for HealthView and AgendaView

Code Block swiftstruct AgendaView: View {		var body: some View {		VStack {			Text("Hello, AgendaView!")		}.onAppear{			print("AgendaView.onAppear")		}.onDisappear(){			print("AgendaView.onDisappear")		}		}}struct HealthView: View {		var body: some View {		VStack {			Text("Hello, HealthView!")		}.onAppear{			print("HealthView.onAppear")		}.onDisappear(){			print("HealthView.onDisappear")		}		}}




Replies  26
Boosts  3
Views  16k
Participants  
Khuffie
Khuffie OP
Aug ’20
As an update, this issue seems to only appear on device.

In the simulator of iOS 14, it works fine.
1
Khuffie
Khuffie OP
Aug ’20
Further information

  • This only appears on actual devices, in the simulator, the issue does not appear.

  • The issue only appears with projects created with the SwiftUI App Life Cycle. The issue does not appear in projects with the UI Kit App Delegate Life Cycle projects.

I submitted a feedback: FB8285799

You can recreate this issue by creating a new project, choosing SwiftUI App from the Life Cycle dropdown, and replacing your ContentView with the following code.

If anyone has any thoughts on a workaround I'd appreciate it!

Code Block swiftimport SwiftUIstruct ContentView: View {		var body: some View {		TabView {			AgendaView()				.tabItem {					Image(systemName: "list.bullet")					Text("Agenda")				}			HealthView()				.tabItem {					Image(systemName: "heart")					Text("Health")				}			SettingsView()				.tabItem {					Image(systemName: "gear")					Text("Settings")				}		}		}}struct AgendaView: View {	var body: some View {		VStack {			Text("Hello, AgendaView!")		}.onAppear{			print("AgendaView.onAppear")		}.onDisappear(){			print("AgendaView.onDisappear")		}	}}struct HealthView: View {	var body: some View {		VStack {			Text("Hello, HealthView!")		}.onAppear{			print("HealthView.onAppear")		}.onDisappear(){			print("HealthView.onDisappear")		}	}}struct SettingsView: View {	var body: some View {		VStack {			Text("Hello, SettingsView!")		}.onAppear{			print("SettingsView.onAppear")		}.onDisappear(){			print("SettingsView.onDisappear")		}	}}


1
malc
malc OP
Sep ’20
If it only appears on device then it is important to know what version of iOS your device is running. I can reproduce a similar problem on iOS 14b8 is that what you tried?

My Feedback is FB8689302
A TabView’s tab onAppear is erroneously called when the tab disappears when another is selected

And I referenced your feedback which sometimes helps get it resolved quicker.
0
trpmap93
trpmap93 OP
Sep ’20
Seeing this issue in the iOS14 release version as well.
1
eth021021
eth021021 OP
Oct ’20
Still experiencing this issue. Really hope they fix this.
2
ToRe23
ToRe23 OP
Nov ’20
This has been fixed with Xcode 12.1.1

onAppear now only is called, wenn the tab actually was selected.
0
ripebanana
ripebanana OP
Nov ’20
This is an issue again with Xcode 12.2 and iOS 14.2 when using TabView with PageTabViewStyle.

.onAppear is called multiple times on the first tab, but only once after scrolling pages.
1
gtasafan
gtasafan OP
Jan ’21
Can confirm, Xcode 12.2 and iOS 14.2 this bug appears. Also: the selection from TabView(selection: $XYZ) is updated after onAppear is called. Though this only happens on the first tab.
0
frees
frees OP
Mar ’21
Any progress here? Is this fixed?
0
CelsoRZ
CelsoRZ OP
Apr ’21
Any update about this issue?
0
CelsoRZ
CelsoRZ OP
Apr ’21
Any update about this issue?
0
fxsalazxar
fxsalazxar OP
Apr ’21
Still... Xcode 12.5 on an application with UI Kit App Delegate Life Cycle and iOS 13 as a target. tested in multiple devices and simulators.
0
count808
count808 OP
May ’21
Agreed. Still broke. Can this be fixed please?
1
zazawu
zazawu OP
Jun ’21

I am seeing the same issue with Xcode 12.4 + Deployment target macOS 10.15

0
onAppear is called when the view hasn't appeared
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