Objective-C Storyboards Segue - Passing data from destination back to sourceViewController - ios

Question

I currently have two view controllers and I linked them up via storyboard segue(navigation controller). When the user presses a button on the first view, the screen goes to the second view. In the second view, there are text fields so that the user can edit the detailed information. When I press the back navigation button, how can I pass that detailed information from the second view controller back to the first view controller?
I use this code to send data from the first view controller to the second view controller
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
SettingsViewController *settingsViewController = [segue sourceViewController];
[settingsViewController setAddressString:[self addressString]];
NSLog(#"Settings address string of SettingsViewController to: %#", [self addressString]);
}
The only way I can think of right now of passing the data from the second view controller to the first view controller is to override the viewWillDisappear method of the second view controller. But is there a way that works by using the segue method? And what is the recommended way of doing this?

Answer 1

You could use delegation.
In your second view controller header file you'll have to create a delegate method.
#protocol SettingsDelegate <NSObject>
- (void)userHasCompletedSettings:(NSArray *)userSettings;
#end
#interface SettingsViewController : UIViewController
#property id<SettingsDelegate>delegate;
// Any other properties you have
#end
In your first view controller when calling your segue you set the delegate to self.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
SettingsViewController *settingsViewController = [segue sourceViewController];
[settingsViewController setAddressString:[self addressString]];
NSLog(#"Settings address string of SettingsViewController to: %#", [self addressString]);
settingsViewController.delegate = self;
}
In your second view controller you need to call the method. You can implement your own Back button so that you can set up an IBAction to call your delegate method.
- (IBAction)backButtonPressed:(id)sender
{
// Package up your settings details in the array
[self userHasCompletedSettings:arrayOfMySettings];
[self dismissViewControllerAnimated:YES completion:nil];
}
You also need to set up the method for the backButtonPressed action to call on the first view controller.
-(void)userHasCompletedSettings:(NSArray *)userSettings
{
// Do what you need to do with the settings.
}

Answer 2

You can pass the detail controller a reference to the master view controller (i.e. self), and let it call methods to set the results.
For example, you can do this:
#interface MasterController : UIViewController
-(void)updateAddressString:(NSString*) address;
#end
#interface DetailController : UIViewController
-(void)setAddressString:(NSString*) address;
#property (nonatomic, readwrite) MasterController *master;
#end
Now you can write this:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
SettingsViewController *settingsViewController = [segue sourceViewController];
[settingsViewController setAddressString:[self addressString]];
[settingsViewController setMaster:self];
NSLog(#"Settings address string of SettingsViewController to: %#", [self addressString]);
}
When the DetailController needs to update the address in the master, it does this:
[_master updateAddressString:updatedAddress];

Answer 3

You can create a class which represents your model object with properties that correspond to fields in SettingsViewController.
You create it and pass to your SettingsViewController in prepareForSegue method and assign it to property/ivar of the current viewController. So you have a model object instance shared between two viewControllers. When you enter information into fields - assign it to your custom model object properties.
Your first viewContoller can get information from properties of the shared model object.