iOS7 UISwitch its Event ValueChanged: Calling continuously is this Bug or what..?

Question

Edit

It's now fixed on ios7.1
Don't do any tweak to fix it.

Edit2

Apparently the same problem happens again in iOS 8.0 and 8.1

Edit3

It's now fixed on ios9.2
Don't do any tweak to fix it.

Hi Today i seen in UISwitch's Event ValueChanged: Calling continuously while i am change to On to Off or Off to On and my finger moved still on right side as well as left side. I atteched GIF image for more clear with NSLog.

enter image description here

My Value Changed Method is:

- (IBAction)changeSwitch:(id)sender{

    if([sender isOn]){
        NSLog(@"Switch is ON");
    } else{
        NSLog(@"Switch is OFF");
    }
    
}

iOS6 the same code of Switch working Fine as we expectation:

enter image description here

so can anyone suggest me that call only one time its state On or off. or is this is a bug or what..?

UPDATE

Here it is my Demo of it:

programmatic Add UISwitch

from XIB adding UISwitch

this is not in my xcode this prob in my as well as my frnd's xcode too — Nitin Gohel, Oct 28 '13 at 06:40
Ya. I too get the same issue when i tried here.. It may be a bug.. — Bala, Oct 28 '13 at 06:42
i've got exactly same problem and i'm going to change UISwitch to just normal button. Cheers! — Joey, Nov 28 '13 at 11:02
It's a bug in uiswitch control instead of adding extra custom component, I applied both the nnarayann's answer and pre's answer together and it fixes my problem — Saeed, Feb 01 '14 at 20:26
im still getting this bug in iOS7.1 on simulator, havent tried device yet, running xcode 5.1.1 — Fonix, May 13 '14 at 09:47
I can see an identical/similar problem with UISwitch in iOS 8.0 and 8.1 — Sea Coast of Tibet, Oct 22 '14 at 20:03
Still here in 9.1. Please file a duplicate of https://openradar.appspot.com/15555929 everyone. This is the only way we're going to get this fixed. — Guillaume Algis, Oct 29 '15 at 10:59
Having now come across this problem in 9.1 on a device, I find that sometimes the ValueChanged event is not generated at all and the method is not invoked — ghr, Dec 15 '15 at 05:03

score 45 · Answer 1 · edited Dec 15 '15 at 16:32

45

Please see the following code:

-(void)viewDidLoad
{
    [super viewDidLoad];    
    UISwitch *mySwitch = [[UISwitch alloc] initWithFrame:CGRectMake(130, 235, 0, 0)];    
    [mySwitch addTarget:self action:@selector(changeSwitch:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:mySwitch];
}

- (void)changeSwitch:(id)sender{
    if([sender isOn]){
        NSLog(@"Switch is ON");
    } else{
        NSLog(@"Switch is OFF");
    }
}

edited Dec 15 '15 at 16:32

casillas

16,351
19
115
215

answered Oct 28 '13 at 07:38

AeroStar

489
3
4

thx for answer as i said i was trying both way and got same result. atlist i knw how to add swtich programmatic as well as from xib sir. – Nitin Gohel Oct 28 '13 at 07:40

nnarayann · Answer 2 · 2014-02-06T17:19:51.123

12

Same bug here. I think I've found a simple workaround. We just have to use a new BOOL that stores the previous state of the UISwitch and an if statement in our IBAction (Value Changed fired) to check that the value of the switch has actually changed.

previousValue = FALSE;

[...]

-(IBAction)mySwitchIBAction {
    if(mySwitch.on == previousValue)
        return;
    // resetting the new switch value to the flag
    previousValue = mySwitch.on;
 }

No more weird behaviors. Hope it helps.

edited Feb 06 '14 at 17:19

answered Jan 17 '14 at 23:15

nnarayann

1,449
19
24

2

this should just say if(mySwitch.on == previousValue) – Keegan Jay Feb 06 '14 at 14:00

score 12 · Answer 3 · edited Feb 10 '16 at 21:30

You can use the UISwitch's .selected property to make sure your code only executes once when the value actual changes. I think this is a great solution because it avoids having to subclass or add new properties.

 //Add action for `ValueChanged`
 [toggleSwitch addTarget:self action:@selector(switchTwisted:) forControlEvents:UIControlEventValueChanged];

 //Handle action
- (void)switchTwisted:(UISwitch *)twistedSwitch
{
    if ([twistedSwitch isOn] && (![twistedSwitch isSelected]))
    {
        [twistedSwitch setSelected:YES];

        //Write code for SwitchON Action
    }
    else if ((![twistedSwitch isOn]) && [twistedSwitch isSelected])
    {
        [twistedSwitch setSelected:NO];

        //Write code for SwitchOFF Action
    }
}

And here it is in Swift:

func doToggle(switch: UISwitch) {
    if switch.on && !switch.selected {
        switch.selected = true
        // SWITCH ACTUALLY CHANGED -- DO SOMETHING HERE
    } else {
        switch.selected = false
    }
}

+1'd this because it led me to using a similar solution of populating the .tag value when I want to ignore the toggle logic. I need the logic to fire sometimes in both on and off mode so the above wasn't quite sufficient. — davidethell, Mar 24 '17 at 20:40

score 9 · Answer 4 · answered Mar 23 '14 at 22:05

If you are using so many switch in your app then there is problem to change the code in all places where t action method of UISwitch is defined.You can make custom switch and handle the events only if value change.

CustomSwitch.h

#import <UIKit/UIKit.h>

@interface Care4TodayCustomSwitch : UISwitch
@end

CustomSwitch.m

@interface CustomSwitch(){
    BOOL previousValue;
}
@end

@implementation CustomSwitch



- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        previousValue = self.isOn;
    }
    return self;
}


-(void)awakeFromNib{
    [super awakeFromNib];
    previousValue = self.isOn;
    self.exclusiveTouch = YES;
}


- (void)setOn:(BOOL)on animated:(BOOL)animated{

    [super setOn:on animated:animated];
    previousValue = on;
}


-(void)sendAction:(SEL)action to:(id)target forEvent:(UIEvent *)event{

    if(previousValue != self.isOn){
        for (id targetForEvent in [self allTargets]) {
            for (id actionForEvent in [self actionsForTarget:targetForEvent forControlEvent:UIControlEventValueChanged]) {
                [super sendAction:NSSelectorFromString(actionForEvent) to:targetForEvent forEvent:event];
            }
        }
        previousValue = self.isOn;
    }
}

@end

We are ignoring events if the value is same as changed value.Put CustomSwitch in all the class of UISwitch in storyboard.This will resolve the issue and call target only once when value changed

This worked for me. It's ideal in that it does not cause extraneous code to be manually added in your implementation files, as it's reusable and hides its implementation inside the class implementation. This is just good design. It would be nice if this answer had more comments though, because I don't really understand why all of the code is there. — James C, Apr 22 '15 at 17:24
Thanks, it worked for me. Can you explain the code a little bit more. @codester — Swayambhu, Dec 17 '15 at 15:30

score 7 · Accepted Answer · answered Oct 28 '13 at 06:47

I got many user that facing same issue so may be this is bug of UISwitch so i found just now for temporary solution of it. I Found one gitHub custom KLSwitch use this for now hope apple will fix this in next update of xCode:-

https://github.com/KieranLafferty/KLSwitch

score 6 · Answer 6 · answered Nov 20 '13 at 17:21

6

If you don't need to react instantly to the switch's value change the following could be a solution:

- (IBAction)switchChanged:(id)sender {
  [NSObject cancelPreviousPerformRequestsWithTarget:self];

  if ([switch isOn]) {
      [self performSelector:@selector(enable) withObject:nil afterDelay:2];
  } else {
      [self performSelector:@selector(disable) withObject:nil afterDelay:2];
  }
}

answered Nov 20 '13 at 17:21

pre

3,475
2
28
43

Worked like a charm in iOS 11.2. In my situation, it fired 2 events in a row (state: off, swiping: off, 1st event: on, 2nd event: off), so a delay of 0.1s is enough for me and not noticeable to a user. – Paul Semionov Dec 13 '17 at 15:04

score 3 · Answer 7 · answered Feb 19 '16 at 18:54

3

This issue is still here as of iOS 9.3 beta. If you don't mind the user not being able to drag outside of the switch, I find that using .TouchUpInside rather than .ValueChanged works reliably.

answered Feb 19 '16 at 18:54

Nick Kohrn

5,779
3
29
49

score 2 · Answer 8 · answered Jan 19 '16 at 13:55

I am still facing same problem in iOS 9.2

I got solution and posing as it might help others

Create count variable to trace number of times method got call
```
int switchMethodCallCount = 0;
```
Save bool value for switch value
```
bool isSwitchOn = No;
```

In Switch's value change method perform desire action for first method call only. When switch value again changes set count value andt bool variable value to default

- (IBAction)frontCameraCaptureSwitchToggle:(id)sender {



//This method will be called multiple times if user drags on Switch,
//But desire action should be perform only on first call of this method


//1. 'switchMethodCallCount' variable is maintain to check number of calles to method,
//2. Action is peform for 'switchMethodCallCount = 1' i.e first call
//3. When switch value change to another state, 'switchMethodCallCount' is reset and desire action perform

switchMethodCallCount++ ;

//NSLog(@"Count --> %d", switchMethodCallCount);

if (switchMethodCallCount == 1) {

//NSLog(@"**************Perform Acction******************");

isSwitchOn = frontCameraCaptureSwitch.on

[self doStuff];

}
else
{
//NSLog(@"Do not perform");


if (frontCameraCaptureSwitch.on != isSwitchOn) {

    switchMethodCallCount = 0;

    isSwitchOn = frontCameraCaptureSwitch.on

    //NSLog(@"Count again start");

    //call value change method again 
    [self frontCameraCaptureSwitchToggle:frontCameraCaptureSwitch];


    }
}


}

I, too, am still facing this issue in 9.2. I implemented your logic, and now it is working as I had intended. — Nick Kohrn, Feb 02 '16 at 02:54

score 2 · Answer 9 · answered Apr 21 '16 at 21:55

This problem plagues me when I tie the switch to other behaviors. Generally things don't like to go from on to on. Here's my simple solution:

@interface MyView : UIView
@parameter (assign) BOOL lastSwitchState;
@parameter (strong) IBOutlet UISwitch *mySwitch;
@end

@implementation MyView

// Standard stuff goes here

- (void)mySetupMethodThatsCalledWhenever
{
    [self.mySwitch addTarget:self action:@selector(switchToggled:) forControlEvents:UIControlEventValueChanged];
}

- (void)switchToggled:(UISwitch *)someSwitch
{
    BOOL newSwitchState = self.mySwitch.on;
    if (newSwitchState == self.lastSwitchState)
    {
        return;
    }
    self.lastSwitchState = newSwitchState;

    // Do your thing
}

Just be sure to also set self.lastSwitchState every time you manually change mySwitch.on! :)

score 1 · Answer 10 · answered Jan 14 '17 at 13:11

This type of problem is often caused by ValueChanged. You don't need to press the button to cause the function to run. It's not a touch event. Every time you programmatically change the switch to on/off, the value changes and it calls the IBAction function again.

@RoNiT had the right answer with:

Swift

func doToggle(switch: UISwitch) {
    if switch.on && !switch.selected {
        switch.selected = true
        // SWITCH ACTUALLY CHANGED -- DO SOMETHING HERE
    } else {
        switch.selected = false
    }
}

score 0 · Answer 11 · answered May 15 '18 at 16:31

0

DispatchQueue.main.async {
        self.mySwitch.setOn(false, animated: true)
    }

This works fine and doesn't calls the selector function again.

answered May 15 '18 at 16:31

anuraagdjain

86
2
7

score 0 · Answer 12 · edited Mar 04 '19 at 10:47

0

This worked for me.

DispatchQueue.main.asyncAfter(deadline: DispatchTime.now()){
    self.switch.isOn = true
}

edited Mar 04 '19 at 10:47

barbsan

3,418
11
21
28

answered Mar 04 '19 at 10:25

user3305074

744
7
19

iOS7 UISwitch its Event ValueChanged: Calling continuously is this Bug or what..?

Edit

Edit2

Edit3

12 Answers12

Linked