How to upload uiviewcontroller after [self dismissModalViewControllerAnimated:YES];

Question

i have an uiviewcontroller which save some NSString in NSUserDefault. When i go back in this way

-(IBAction)goBack:(id)sender{
    [self dismissModalViewControllerAnimated:YES];
    [self viewWillAppear:YES];
}

to another uiviewcontroller that have to use that NSString saved in NSUserDefault. In viewWillApper it loads this nsstring. when i launch application the first time it load data correctly, if i turn back from another view no. What can i do?

Answer 1

Register the view controller that cares about the value from defaults as an observer of the NSUserDefaultsDidChangeNotification. When you receive the notification, get the value from defaults and do whatever you need to with it.

If you are simply presenting a modal view controller in which you are setting the string, and it is the parent view controller that needs to know the new value, then you could just have a property on the parent view controller and set that as your modal view controller is dismissed.

The sample code you have there I assume is from your modal view controller - this will have no effect on the presenting view controller (you are calling viewWillAppear on the modal controller as you are dismissing it, a bad idea) and viewWillAppear is not called on a view controller when it has dismissed a modal view controller.

To do my second suggestion, in your parent view controller's header:

@property (nonatomic,copy) NSString *stringFromDefaults;

In the .m file:

@synthesize stringFromDefaults;

In your viewWillAppear, where you currently get the value, assign in to the property instead:

self.stringFromDefaults = [[NSUserDefaults standardUserDefaults] stringForKey:@"stringValue"];

From your modal view controller:

-(IBAction)goBack:(id)sender
{
    [(ParentViewController*)self.parentViewController setStringFromDefaults:newStringValue];
    [self dismissModalViewControllerAnimated:YES];
}

Where newStringValue is the updated string value that you have also stored in defaults.