When I use SwiftUI to make my view,I can't make the tap event work.
My Code like:
VStack{
HStack{
//SomeView...
}
.onTapGesture {
print("HStack Tap Work")
}
}
.onTapGesture {
print("VStack Tap Work")
}
And I just want to print "VStack Tap Work" when i tap the other area of VStack expect the HStack,and print "HStack Tap Work" when i tap the HStack.
But it always print "VStack Tap Work".So how can i resolve it?
The handling order might depend on real views hierarchy (because stacks usually tight around content), so try to separate gestures by priority, like
HStack {
//SomeView...
}.highPriorityGesture(TapGesture().onEnded { // high priority !!
print("HStack Tap Works")
})
Related
I've encountered a bug in SwiftUI that could cause unintended interaction with the app without the user's knowledge.
Description
The problem seems to be related to using #Binding properties on the View structs when used in conjunction with NavigationStack and NavigationLink. If you use NavigationView with NavigationLink to display a DetailView that accepts a $Binding parameter, and that parameter is used in some sort of condition in the DetailView, it will result in unexpected behavior.
To clearly show the problem, I'm using a DetailView where the "Blue" or "Red" view is shown depending on the #Binding property. Each of those views has a .onTapGesture() modifier that prints some text when tapped. The problem is that if the Red view is shown, it detects and triggers the action on the Blue view, which could lead to unintended changes in many apps without the user's knowledge.
Replication of the problem
You can easily copy and paste this code into your own file to replicate the bug. To see the unexpected behavior, run the code below and follow these steps on the simulator:
Tap on the DetailView in the NavigationLink.
Tap the blue color area and the console will print "Blue Tapped".
Tap the "RED BUTTON" to switch to the other view.
Tap the red color area and the console will print "Red Tapped".
Now try to tap a blank space below the red area (where the blue area was previously located). The console will print "BLUE tapped" - this is the problem, it seems that the blue view is still active there.
I tested this behavior on: XCode 14.1, iPhone 13 Pro 16.1 iOS Simulator, and on a real iPhone with iOS 16. The result was always the same.
import SwiftUI
struct ContentView: View {
var body: some View {
NavView()
}
}
struct NavView: View {
#State private var colourShowed: Int = 1
var body: some View {
// If the DetailView() was shown directly, (without the NavigationLink and NavigationStack) there would be no such a bug.
// DetailView(colourShowed: $colourShowed)
// The bug is obvious when using the NavigationStack() with the NavigationLink()
NavigationStack {
Form {
NavigationLink(destination: { DetailView(colourShowed: $colourShowed) },
label: { Text("Detail View") })
}
}
}
}
struct DetailView: View {
// It seems like the problem is related to this #Binding property when used in conjunction
// with the NavigationLink in "NavView" View above.
#Binding var colourShowed: Int
var body: some View {
ScrollView {
VStack(spacing: 20){
HStack {
Button("BLUE BUTTON", action: {colourShowed = 1})
Spacer()
Button("RED BUTTON", action: {colourShowed = 2})
}
if colourShowed == 1 {
Color.blue
.frame(height: 500)
// the onTapeGesture() is stillActive here even when the "colourShowed" property is set to '2' so this
// view should therefore be deinitialized.
.onTapGesture {
print("BLUE tapped")
}
// The onAppear() doesn't execute when switching from the Red view to the Blue view.
// It seems like the "Blue" View does not deinitialize itself after being previously shown.
.onAppear(perform: {print("Blue appeared")})
}
else {
Color.red
.frame(height: 100)
.onTapGesture {
print("RED tapped")
}
.onAppear(perform: {print("Red appeared")})
}
}
}
}
}
Is there any solution to prevent this?
This is a common problem encountered by those new to Swift and value semantics, you can fix it by using something called a "capture list" like this:
NavigationLink(destination: { [colourShowed] in
It occurred because DetailView wasn't re-init with the new value of colourShowed when it changed. Nothing in body was using it so SwiftUI's dependency tracking didn't think body had to be recomputed. But since you rely on DetailView being init with a new value you have to add it to the capture list to force body to be recomputed and init a new DetailView.
Here are other questions about the same problem with .sheet and .task.
I am aware I asked a similar question before, but it seems like I have not understood the core concept of how to present a custom toolbar above a keyboard.
I successfully solved my problem on how to present one with a search field (SwiftUI 2.0: Custom keyboard elements).
Now I want to present a keyboard when a textfield within a detail view of a list is clicked, but again the keyboard toolbar does not show. Does anyone have an idea why?
VStack {
Text("Weight:")
TextField("0", text: $weight)
.keyboardType(.decimalPad)
.toolbar {
ToolbarItemGroup(placement: .keyboard) {
HStack {
Button(action: {
print("Set bodyweight")
},
label: {Text("Bodyweight")
})
Picker("", selection: $weightType) {
ForEach(weightSuffix.allCases, id: \.self) {
Text($0.rawValue)
}
}
.pickerStyle(.segmented)
}
}
}
}
.border(Color.red)
[EDIT]
After Asperi´s comment I Created a small git: https://gist.github.com/joni8a/bc021ef597cb6efa1ab0ca277d602478
Now it gets even weirder, if I attach the toolbar modifier to the list element I get the intended behavior, showing 1 button above the toolbar
If I append the toolbar modifier to the textfield inside the detail view I get the following result:
I think this is a weird behavior. It seems like I have not understood a core concept of SwiftUI. On the other hand if I can't attach the viewmodifer to the textfield itself, it is hard to uncouple the detail view from the list view ...
the Form view seems to create troubles using the newest SwiftUI (I'm new to it and haven't tested it in older version tbh).
The simple code executes the onTapGesture function correctly when clicking on the button, although it disables all the user feedback (so not visual change in the button on pressing, hold and release) and also does not execute the button action anymore:
var body: some View
{
Form
{
Button(action: {
print("button action")
})
{
Text("Button")
}
.onTapGesture
{
print("tap button")
}
}
.onTapGesture
{
print("tap form")
}
}
When exchanging Form with HStack the visual feedback and console prints work. So it definitely seems to be an issue with the Form view.
When commenting the onTapGesture Form function the button feedback works again. So only the onTapGesture on the Form blocks all child interaction.
Does anyone know what this is - and is there a workaround?
So I have a view with List, also this view has side menu. I added tapGesture to my VStack to dismiss side menu when it's open, but then I face issue, tapGesture is blocking onDelete method of List. Any ideas how to fix that??
Here is code example:
VStack {
.....
List {
ForEach(){
//list elements here
}
.onDelete {
// delete action here
}
}
}
.onTapGesture {
// action here
}
Also, if while deleting I swipe once till the end, it's working. But if I swipe just a little and try to press Delete button nothing happens.
Replace your .onTapGesture with the simultaneousGesture modifier.
.simultaneousGesture(TapGesture().onEnded {
// action here
})
SwiftUI makes it very easy to build declarative UIs. However, sometimes they assume defaults that are not necessarily what we want.
Example:
When adding two buttons inside a list row, SwiftUI automatically makes the whole row touchable, and both button's actions are called on row tap. This is the default behavior, as demonstrated in their WWDC videos.
But I do not want this behavior. I want both buttons to work properly, and the row to not be tappable.
Question:
How can we tell our Guacamole expert (to use the WWDC reference) to stop assuming how I want my list (or any other behavior) to work?
Any help would be appreciated.
If the List's default behavior is not required, you could use a VStack:
struct ContentView: View {
var body: some View {
VStack {
Button(action: {
print("foo")
}) {
Image(systemName: "photo")
}
Button(action: {
print("bar")
}) {
Image(systemName: "photo")
}
}
}
}
However if List is really required, then it could be customized by writing a custom ListStyle.
(Also take a look at this question: How to change ListStyle in List.)
It seems that SomethingStyle protocol is the way Apple wants developers to use to modify native SwiftUI elements/behavior. Another example would be ButtonStyle or TextFieldStyle, etc.
I am under the impression that Apple wants to enforce their style guidelines. Also to add onto #backslash-f answer you could also just use a for each instead of a list, this will give you a similar effect and allow much more customization.
struct doubleList: View {
var body: some View {
VStack{
ForEach(1 ..< 10) {index in
Button(action: {
print("foo")
}) {
Image(systemName: "photo")
}
}
}
}
}
Another option to try would be to wrap an UITableView into an UIViewRepresentable and try to enable buttons that way
It seems there might be another way around this by using tap gestures
Image(systemName: "photo")
.gesture(TapGesture().onEnded() {
print("action2")
})