Question

I came cross this code as shown below. how could I save existing annotation pins info to NSUserdefault without creating any buttons(IBAction)? Should I put NSUserDefault code into viewWillDisappear? Is that the right way to do it?

To save:

NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];
[ud setDouble:location.latitude forKey:@"savedCoordinate-latitude"];
[ud setDouble:location.longitude forKey:@"savedCoordinate-longitude"];
[ud setBool:YES forKey:@"savedCoordinate-exists"];
[ud synchronize];

Answer 1

You can put that code wherever you want, when you want to save that data. NSUserDefaults is accessible anywhere. Synchronize is what saves it to disk.