Make a variable with a fixed value

Question

I've a view controller with one variable x, in ViewController.h:

@property(nonatomic) int x;

Is it possible to set the recent value of x fixed? For example a method sets x to the value 5 and when this view controller is reloaded the value of x should be 5 and not 0 again as it is now.

e.g. in a ViewController:

- (IBAction)btnPressed:(id)sender {
_x++;
}

x should be increase after each tapping of the button >>> 0,1,2,3,4...(even after a restart of the app)

Thanks to all your answers in advance.

Answer 1

You can use simple and clear methods to store your value.

Your interface:

@interface FirstViewController : UIViewController

@property (nonatomic) int x;
@property (strong, nonatomic) IBOutlet UILabel *label;

- (IBAction)buttonPressed:(id)sender;
- (void)updateLabel;

@end

Your setter:

- (void)setX:(int)x
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setInteger:x forKey:@"MyValue"];
    [userDefaults synchronize];
}

Your getter:

- (int)x
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    return [userDefaults integerForKey:@"MyValue"];
}

Your action:

- (IBAction)buttonPressed:(id)sender 
{
    [self updateLabel];
    self.x++;
}

Your viewDidAppear: method:

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self updateLabel];
}

Your method to update label:

- (void)updateLabel
{
    [self.label setText:[NSString stringWithFormat:@"%d", self.x]];
}

Notes:

1. @"MyValue" has to be unique string, because UserDefaults is only instance for whole application.
2. integerForKey is method to store int values only.

Updated: I'm sorry, integerForKey is right method here, thanks to @JoshHinman.