Is there a way to limit NSNotification? - ios

Question

I use NSNotification to send notification when switch is changed position to start updating annotations on map. My problem is that I have 8 switches and when user change position of few switches, map updates for many times. How a limit that to just one notification?
- (IBAction)saveSwitch:(id)sender
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"MyAppSettingsChanged" object:self userInfo:nil];
NSUserDefaults *defs1 = [NSUserDefaults standardUserDefaults];
[defs1 setBool: blackSwitch.on forKey: #"blackKey"];
NSUserDefaults *defs2 = [NSUserDefaults standardUserDefaults];
[defs2 setBool: greenSwitch.on forKey: #"greenKey"];
NSUserDefaults *defs3 = [NSUserDefaults standardUserDefaults];
[defs3 setBool: purpleSwitch.on forKey: #"purpleKey"];
NSUserDefaults *defs4 = [NSUserDefaults standardUserDefaults];
[defs4 setBool: orangeSwitch.on forKey: #"orangeKey"];
NSUserDefaults *defs5 = [NSUserDefaults standardUserDefaults];
[defs5 setBool: blueSwitch.on forKey: #"blueKey"];
NSUserDefaults *defs6 = [NSUserDefaults standardUserDefaults];
[defs6 setBool: redSwitch.on forKey: #"redKey"];
NSUserDefaults *defs7 = [NSUserDefaults standardUserDefaults];
[defs7 setBool: darkblueSwitch.on forKey: #"darkblueKey"];
NSUserDefaults *defs8 = [NSUserDefaults standardUserDefaults];
[defs8 setBool: yellowSwitch.on forKey: #"yellowKey"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
In another view
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(onAppSettingsChanged:) name:#"MyAppSettingsChanged" object:nil];
}
Updating annotations
- (void) onAppSettingsChanged:(NSNotification *)notification {
NSLog(#"Settings was changed");
//Create the thread
[NSThread detachNewThreadSelector:#selector(loadPList) toTarget:self withObject:nil];
}

Answer 1

You must update some BOOLean value to indicate that you are not currently processing an update, and proceed accordingly. I.E.
- (void) onAppSettingsChanged:(NSNotification *)notification {
  NSLog(#"Settings was changed");
if (!myBoolToIndicateProcessing) {
  //Create the thread
myBoolToIndicateProcessing = YES;
  [NSThread detachNewThreadSelector:#selector(loadPList) toTarget:self withObject:nil];
}
}
Then, when the reload has finished, set the BOOL back to NO.