How do I save and load a picture to view on another view controller using nsuserdefaults and .hidden

Question

I have to squares on the first view controller its hidden at anytime and when the app launches you have two button white and black. when the user presses on either button and press on back to view 1 it shows either the white square and black square depending on which the user picked.

code below:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidAppear:(BOOL)animated {
    NSUserDefaults *SetBlack = [NSUserDefaults standardUserDefaults];
    blacksquare.hidden = [SetBlack boolForKey:@"black"];

    NSUserDefaults *SetWhite = [NSUserDefaults standardUserDefaults];
    whitesquare.hidden = [SetWhite boolForKey:@"white"];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

and

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (IBAction)black:(id)sender{
    NSUserDefaults *SetBlack = [NSUserDefaults standardUserDefaults];
    [SetBlack setBool:NO forKey:@"black"];
}

- (IBAction)white:(id)sender{
    NSUserDefaults *SetWhite = [NSUserDefaults standardUserDefaults];
    [SetWhite setBool:NO forKey:@"black"];
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

Just change name of your functions, say, on setBlack: and setWhite:. The problem is that you have a local variable black\white and global function black/white. — Vladislav Kovalyov, Jul 09 '14 at 22:41
Update your question with the .h file showing the ivars (and please format it properly). — rmaddy, Jul 09 '14 at 22:44
Change `- (IBAction)black:(id)sender` to `- (IBAction)setBlack:(id)sender`. And the same for `- (IBAction)white:(id)sender`. — Vladislav Kovalyov, Jul 09 '14 at 22:45
Ok i fixed the issues but when I either press on white or black and go back to the first view controller both images show up. Any idea? — Tyler Schoenau, Jul 09 '14 at 22:50
Bools in NSUserDefaults default to NO. Since you never set it to YES, both will always be visible. — Craig Siemens, Jul 09 '14 at 22:53
Ok but I want the user to pick between black or white and it will show upon the users choice. — Tyler Schoenau, Jul 09 '14 at 22:57
It's not good practice to use NSUserDefaults to pass data between controllers. If you need the data to persist between launches of your app, then NSUserDefaults is appropriate. — rdelmar, Jul 10 '14 at 00:32

score 1 · Answer 1 · answered Jul 10 '14 at 09:39

- (IBAction)black:(id)sender{
NSUserDefaults *SetBlack = [NSUserDefaults standardUserDefaults];
[SetBlack setBool:NO forKey:@"black"];
}

- (IBAction)white:(id)sender{
NSUserDefaults *SetWhite = [NSUserDefaults standardUserDefaults];
[SetWhite setBool:NO forKey:@"black"];
}

The above code should be like this

 - (IBAction)black:(id)sender{
NSUserDefaults *SetBlack = [NSUserDefaults standardUserDefaults];
[SetBlack setBool:NO forKey:@"black"];
[SetBlack synchronize]; // added synchronize method
}

- (IBAction)white:(id)sender{
NSUserDefaults *SetWhite = [NSUserDefaults standardUserDefaults];
[SetWhite setBool:NO forKey:@"black"];
[SetWhite synchronize]; // added synchronize method
}

From the documentation for NSUserDefaults synchronize

Because this method is automatically invoked at periodic intervals, use this method only if you cannot wait for the automatic synchronization (for example, if your application is about to exit) or if you want to update the user defaults to what is on disk even though you have not made any changes.

score 0 · Answer 2 · answered Jul 10 '14 at 08:44

0

You will have to use [[NSUserDefaults standardDefaults] synchronize]; after setting value in NSUserDefaults to save.

answered Jul 10 '14 at 08:44

Ritu

661
3
8

How do I save and load a picture to view on another view controller using nsuserdefaults and .hidden

2 Answers2