change uiswitch based on state of another uiswitch - ios

Question

I basically have two switch buttons that i want the user to select from either two player or group play. However i dont want the user to be able to select both of these so idealy when the user clicks one the other turns off. How would be best to implement this?
-(void)stateSwitchedtwoplayer:(id)sender {
UISwitch *tswitch = (UISwitch *)sender;
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
[defaults setObject: tswitch.isOn ? #"YES" : #"NO" forKey:#"twoplayerswitch"];
[defaults synchronize];
}
-(void)stateSwitchedgroup:(id)sender {
UISwitch *tswitch = (UISwitch *)sender;
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
[defaults setObject: tswitch.isOn ? #"YES" : #"NO" forKey:#"groupswitch"];
[defaults synchronize];
}

Answer 1

Do you have references for both switches ?
If yes, it will be something like this :
-(void)stateSwitchedtwoplayer:(id)sender {
UISwitch *tswitch = (UISwitch *)sender;
self.switchGroup.on =! tswitch.isOn; //reference to group switch
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
[defaults setBool: tswitch.isOn forKey:#"twoplayerswitch"];
[defaults setBool: !tswitch.isOn forKey:#"groupswitch"];
[defaults synchronize];
}
-(void)stateSwitchedgroup:(id)sender {
UISwitch *tswitch = (UISwitch *)sender;
self.switchTwoPlayer.on =! tswitch.isOn; //reference to two players switch
NSUserDefaults *defaults =[NSUserDefaults standardUserDefaults];
[defaults setBool: tswitch.isOn forKey:#"groupswitch"];
[defaults setBool: tswitch.isOn forKey:#"twoplayerswitch"];
[defaults synchronize];
}
but if you want that both switches can be off, then you just need to change it on
self.switchGroup.on =! tswitch.isOn == YES; //reference to group switch
self.switchTwoPlayer.on =! tswitch.isOn == YES; //reference to two players switch

Answer 2

You would implement this with KVO. You can find documentation at: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/KeyValueObserving/Articles/KVOCompliance.html. But i would suggest you not to.
You should implement some UISegmentedControl for these type of operations. Why don't you take a look at: https://developer.apple.com/library/ios/documentation/uikit/reference/UISegmentedControl_Class/Reference/UISegmentedControl.html.