NSUserDefaults not saving?

Whitehk · 07-01-2010, 12:39 PM

Hi. I'm saving an NSInteger using NSUserDefaults, and it doesn't seem to be saving it. Every time I kill the app and go back in, it will go back to zero. The idea of it is that the user will click a button and numberOfTimesPressed (the NSInteger) will increase by 1. Here is how I save it:

Code:

-(IBAction)buttonPressed {
	numberOfTimesPressedValue += 1;
	
	NSUserDefaults *numberOfTimesPressedSaved = [NSUserDefaults standardUserDefaults];
	[numberOfTimesPressedSaved setInteger:numberOfTimesPressedValue forKey:@"numberOfTimesPressed"];
	
	label.text = [NSString stringWithFormat:@"%d", numberOfTimesPressedValue];
}

Here is how I retrieve it when the user kills the app then comes back:

Code:

-(void)viewDidLoad {
	[super viewDidLoad];
	
	NSUserDefaults *numberOfTimesPressedSaved = [NSUserDefaults standardUserDefaults];
	numberOfTimesPressedValue = [numberOfTimesPressedSaved integerForKey:@"numberOfTimesPressed"];
	
	label.text = [NSString stringWithFormat:@"%d", numberOfTimesPressedValue];
}

This viewDidLoad method is in the same .m file as the IBAction. Any ideas as to why it wouldn't be saving? Thanks in advance.

Duncan C · 07-01-2010, 01:58 PM

Quote:

Originally Posted by Whitehk

Hi. I'm saving an NSInteger using NSUserDefaults, and it doesn't seem to be saving it. Every time I kill the app and go back in, it will go back to zero. The idea of it is that the user will click a button and numberOfTimesPressed (the NSInteger) will increase by 1. Here is how I save it:

Code:

-(IBAction)buttonPressed {
	numberOfTimesPressedValue += 1;
	
	NSUserDefaults *numberOfTimesPressedSaved = [NSUserDefaults standardUserDefaults];
	[numberOfTimesPressedSaved setInteger:numberOfTimesPressedValue forKey:@"numberOfTimesPressed"];
	
	label.text = [NSString stringWithFormat:@"%d", numberOfTimesPressedValue];
}

Here is how I retrieve it when the user kills the app then comes back:

Code:

-(void)viewDidLoad {
	[super viewDidLoad];
	
	NSUserDefaults *numberOfTimesPressedSaved = [NSUserDefaults standardUserDefaults];
	numberOfTimesPressedValue = [numberOfTimesPressedSaved integerForKey:@"numberOfTimesPressed"];
	
	label.text = [NSString stringWithFormat:@"%d", numberOfTimesPressedValue];
}

This viewDidLoad method is in the same .m file as the IBAction. Any ideas as to why it wouldn't be saving? Thanks in advance.

User defaults are held in memory, and not necessarily written to disk.

Add a call to [ [NSUserDefaults standardUserDefaults] synchronize] every time you change user defaults.

It's worse with iOS 4, because your app doesn't get a terminate message when the user presses the home key, and people usually put their code to save things to disk there.

Whitehk · 07-01-2010, 02:09 PM

Quote:

Originally Posted by Duncan C

User defaults are held in memory, and not necessarily written to disk.

Add a call to [ [NSUserDefaults standardUserDefaults] synchronize] every time you change user defaults.

It's worse with iOS 4, because your app doesn't get a terminate message when the user presses the home key, and people usually put their code to save things to disk there.

That was the problem! Thanks a bunch for both the solution and quick reply!