iOS7 UISwitch its Event ValueChanged: Calling continuously is this Bug or what..?
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.
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:
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
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");
}
}
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.
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
}
}
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
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