Question

I’ve got a VC (root) that calls a Modal Segue to a UINavigatioController (settings). The user can change what they want. How do I let the first VC (root) know that the changes are done. the UINav’s delegate is the (root) VC. any ideas to pass data back from a modal segue? cheers

Answer 1

Use your AppDelegate as a central communication hub that child VCs can call, and pass data to. Try the following:

First set up a shared delegate class method, and a method to pass data to a child VC, in your AppDelegate like so:

// In MyAppDelegate.h

#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>

@interface MyAppDelegate : NSObject {
// rootviewcontroller is the parent of your UINavigationController
UIViewController *rootViewController;
}
+ (MyAppDelegate *)sharedAppDelegate;
-(void)passData:(NSString*)myString;

and so..

// In MyAppDelegate.m

#import "MyAppDelegate.h"

@implementation MyAppDelegate.m

+ (MyAppDelegate.m *)sharedAppDelegate
{
    return (MyAppDelegate.m *) [UIApplication sharedApplication].delegate;
}

-(void)passData:(NSString*)myString{

// pass data to parent of UINavigationController
[rootViewController hereIsSomeData:myString];

}

and then from the .m file of your UINavigationController (VC.m), you import your AppDelegate class and instantiate a shared delegate, which will essentially let you “call” the AppDelegate and send it data..

// In VC.m
#import "MyAppDelegate.h";

// ...
NSString *myString = @"alskdjfalsdjfq324r";
[[MyAppDelegate sharedAppDelegate] passData:myString];