Forum› Xamarin.Forms
How not to change the state of the switch when pressed
lucagto
Member ✭✭
Member ✭✭
On iOS I need not to change the state of the switch when pressed,
I would like to change its state only using the command
switch.IsToggled = true
I would like switcth.Toggled + = ...to call a function but not to affect the state of the switch
Does anyone know how to do it?
Many thanks.
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Best Answer
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PaulNTU
USMember ✭✭✭
Ok the solution I have come up with is to use a frame with a tap gesture recogniser. Make the switch input transparent (It wont accept taps and will pass down on the parent frame)
XAML
Frame x:Name="clickframe">
Switch InputTransparent="True"/>
/Frame>C# code behind
// On form load Frame f = this.FindByName("clickframe") as Frame; TapGestureRecognizer tap = new TapGestureRecognizer(); tap.Tapped += Tap_Tapped; f.GestureRecognizers.Add(tap);Your tap code goes in this function
private void Tap_Tapped(object sender, EventArgs e) { // Toggle is tapped over }5
Answers
Would setting the enabled state for the control to false work for this?
You want this event fired when the Switch is changed programmatically only, or also when the user taps on the Switch?
Do you want the Switch to appear disabled?
Depending on your answers to the above 2 questions, you might simply want to set IsEnabled=false, or you might want to overlay a transparent BoxView on top of the Switch, using the BoxView's InputTransparent as required to prevent clicks etc reaching the Switch, and setting the Switch's IsTabStop to false to prevent the user tabbing to the Switch.
Be aware that having a Switch that appears Enabled, but that does not operate as the users would expect, is going to confuse the users.
if I use > sblue.IsEnabled = false I can't press on it anymore, I want to be able to press the switch but I don't want it to change its state
@JohnHardman
I want the event to active just with user pressure, I don't want the switch to appear disabled.
I want the user to be able to press the switch to activate the function but the switch must not change its state in pressure, but only by code.
Once it is toggled by the user can you not set its switch.IsToggled state to return it back to its pre pressed state again
No because the animation would be seen anyway
Curiosity got the better of me. Why in the world do you want to do this?
Perhaps there is a better UI solution.
This switch I need to activate or deactivate the bluetooth, on iOS it is not possible to change the bluetooth status without going through the ios settings window, so when a user presses on the switch the ios bluetooth settings will open, after setting bluetooth the user returns to the application and the status of the switch is updated with the bluetooth status, which is why I want no animation to occur at the pressure on the switch.
I hope I was clear.
Ok the solution I have come up with is to use a frame with a tap gesture recogniser. Make the switch input transparent (It wont accept taps and will pass down on the parent frame)
XAML
Frame x:Name="clickframe">
Switch InputTransparent="True"/>
/Frame>
C# code behind
// On form load Frame f = this.FindByName("clickframe") as Frame; TapGestureRecognizer tap = new TapGestureRecognizer(); tap.Tapped += Tap_Tapped; f.GestureRecognizers.Add(tap);Your tap code goes in this function
private void Tap_Tapped(object sender, EventArgs e) { // Toggle is tapped over }@lucatgo
Yes, it's clear what you want to accomplish. But I think this is a poor UI design, no offense.
It's an unexpected behavior and will confuse the users.
When you tap a switch the expected behavior is to have the switch simply slide over. Nothing else. Certainly not open a dialog.
What I would do is have a button "Turn on BlueTooth" which then launches your settings dialog.
The user will understand this better.
Besides.... even if you decide to use a switch, why can't you simply bind it to a flag in your VM which then kicks off your dialog code.
Why the smoke-and-mirrors?
@RHudson
I'm not the one who decides the graphic interface of the application, I was told to do so and so I have to do.
It's a code shared with android, on andorid the switch is able to disable the bluetooth without going in the settings, probably they want to get a coherent interface between the two operating systems.
@PaulNTU
Ok so it works, it's not elegant because I would have preferred to overwrite the behavior of the switch on ios, but that's fine.
Now I'm trying to update the status of the switch after setting it from the ios settings, I'm using the
OnAppearing ()function, but it's not working.Frame f = this.FindByName("click") as Frame; if (Device.RuntimePlatform == Device.Android) { sblue.Toggled += Change_Status_Bluetooth; } else { TapGestureRecognizer tap = new TapGestureRecognizer(); sblue.InputTransparent = true; tap.Tapped += Change_Status_BluetoothIOS; f.GestureRecognizers.Add(tap); } sblue.IsToggled = Utils.BluetoothIsActive(); ... private void Change_Status_BluetoothIOS(object sender, EventArgs e) { if (firstAccess) { var t = Task.Run(() => { Device.BeginInvokeOnMainThread(() => { Utils.ChangeStateBluetooth(); }); }); } } protected override void OnAppearing() { sblue.IsToggled = Utils.BluetoothIsActive(); }Some advice?
thanks a lot
Clarify "it's not working". What happens? What do you expect to happen? Have you added breakpoints and/or traced through the code to see which code gets executed?
@lucatgo Can you not do something like this?
bool _bluetoothState; public bool BlueToothState { get { return _bluetoothState; } set { if (firstAccess) { var t = Task.Run(() => { Device.BeginInvokeOnMainThread(() => { Utils.ChangeStateBluetooth(); }); }); } } } protected override void OnAppearing() { _bluetoothState = Utils.BluetoothIsActive(); }And bind your switch to BluetoothState ?
When I press on the switch opens the ios bluetooth settings, when I go back to my app the status of the switch is not updated compared to what I set in the bluetooth settings
Execution passes from the onappearing function but the status of the switch does not update.
@RHudson
It looks very similar to what I'm doing, I don't understand how it can update the status of the switch like that, I'm sorry but I'm new to Xamarin and C #.
I should probably use
OnResume(), but I'm not understanding how to do it.@lucagto When the user taps the switch, the code in the Set {} will fire.
You don't need to worry about updating the status of the switch. That's what MVVM and binding is all about. The switch will look after itself.
Have a look at some MVVM basics, perhaps
https://docs.microsoft.com/en-us/xamarin/xamarin-forms/xaml/xaml-basics/data-bindings-to-mvvm
or
https://docs.microsoft.com/en-us/xamarin/xamarin-forms/enterprise-application-patterns/mvvm
or
https://redpillxamarin.com/2017/01/08/401-revisiting-mvvm/
No no no no no no no no. Review those basics first.
(Note to self... I need to change the cardinal's bubble caption. XF is actually very stable now, not like 4 years ago)
@RHudson
I read those guides, at the moment I can tell you that I don't understand how to use your function, I can't do
switch.Toggled + = BlueToothStateBy "Execution passes from the onappearing function", you mean that OnAppearing is called and the line "sblue.IsToggled = Utils.BluetoothIsActive();" is executed in the scenario where control returns from the settings page to your app?
Do you call base.OnAppearing() ? (you haven't posted your entire page class, so we don't know if you have a base page class that you use)
The code that you posted does not show what sblue is, nor what Utils.BluetoothIsActive does. To identify the cause of the problem with certainty, we need that.
For now I have solved in the following way: I used the frame as suggested above, I created a function that updates the switch that is called in the App.cs in the onResume, checking if they are in the correct page, otherwise onResume does not intervene.
Thank you all for your help