Trying to pass data between viewControllers - ios5

Question

I have a sequence of 4 viewControllers inside a NavigationController, each grabs a few textFields of input from the user which are stored in a NSMutableDictionary.
Each of the VC's set's itself up as the delegate of the nextVC before it segues, it also passes the NSMutDict along.
This works fine.
What I don't understand is this:
Say I have filled in the 5 textFields in VC1. Then I set myself as the delegate of VC2, pass VC2 the dictionary with the input data and segue to VC2. In VC2 I fill in another 4 textFields and add these to the dictionary. If I then decide I need to change something in VC1 I tap the back button and amend the data. But when I go forwards again I lose the stuff I input on VC2.
How do I pass the dictionary back to VC1 with the added info so that when it gets passed forwards to VC2 again it has everything in it?
The delegate (VC1) has a method to update its dictionary with the dictionary in VC2.
I have also customised the backBarButtonItem in VC2 by setting it in the prepareForSegue: method in VC1.
I think I'm getting close but...
I can only get the target actions to work by setting a leftBarButtonItem in VC2 and using that instead of the default back button.
Setting the back button in VC1 (prepareForSegue:) doesn't seem to allow any target or action to be set.
I know I can't set the back button in VC2, so what can I do? Can I set the target and action of the back button from VC2 using the delegate?
I think it may be something to do with UINavigationBarDelegate but I can't figure out where to put what with that. I tried setting it up in VC2 but it didn't do anything.
TIA.
Here's the relevant code:
Protocol:
#import <Foundation/Foundation.h>
#protocol IAXAddNewUserDelegate <NSObject>
#required
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData;
#end
From VC1.h:
#import "IAXAddNewUserDelegate.h"
#interface IAXAddNewUser1 : UITableViewController <UITextFieldDelegate, UIAlertViewDelegate, IAXAddNewUserDelegate>
#property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (strong, nonatomic) User *selectedUser;
#property (strong, nonatomic) User *aNewUser;
#property BOOL isFirstUser;
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData;
#end
From VC1.m:
#pragma mark - Segues
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"AddUser2"]) {
IAXAddNewUser2 *addUser2VC = segue.destinationViewController;
addUser2VC.managedObjectContext = self.managedObjectContext;
addUser2VC.progressTotal = self.progressTotal;
addUser2VC.isFirstUser = self.isFirstUser;
addUser2VC.userData = self.userData;
addUser2VC.delegate = self;
if (self.selectedUser) {
addUser2VC.selectedUser = self.selectedUser;
}
self.title = #"Step 1";
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:#"Back"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(passDataBack:)];
self.navigationItem.backBarButtonItem = backButton;
}
}
#pragma mark - IAXAddNewUserDelegate Methods
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData
{
self.userData = newData;
NSLog(#"Updated AddUserVC1");
}
From VC2.m
-(void)passDataBack:(id)sender
{
NSLog(#"Sending Data Back to VC1");
[self.delegate updateNewUserDataWithData:self.userData];
[self.navigationController popViewControllerAnimated:YES];
}

Answer 1

If you're updating all the dictionaries from all the other dictionaries, try using a singleton. You can see an example here: https://stackoverflow.com/a/9690731/542400
Also, here's some code:
MainDictionary.h
#interface MainDictionary : NSObject{
NSMutableDictionary *dictionary;
}
+(MainDictionary *)sharedDictionary;
-(NSString *)getStringForKey:(NSString *)string;
-(void)setString:(NSString *)string forKey:(NSString *)key;
#end
MainDictionary.m
#import "MainDictionary.h"
static MainDictionary *sharedDictionary;
#implementation MainDictionary
-(id)init{
self = [super init];
dictionary = [[NSMutableDictionary alloc] init];
// if you want to add anything preliminary to the dictionary, do it here
return self;
}
+(MainDictionary *)sharedDictionary{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedDictionary = [[self alloc] init];
});
return sharedDictionary;
}
-(NSString *)getStringForKey:(NSString *)string{
return [dictionary objectForKey:string];
}
-(void)setString:(NSString *)string forKey:(NSString *)key{
[dictionary setValue:string forKey:key];
}
#end
Now #import MainDictionary.h, and any time you want to access or set values in that dictionary (in this example, when your textFields end editing), just do this:
-(void)textFieldDidEndEditing:(UITextField *)textField{
if(textField == textField1){
[[MainDictionary sharedDictionary] setString: textField.text forKey:#"textField1"];
}
}
or:
-(void)viewWillAppear{
textField1.text = [[MainDictionary sharedDictionary] getStringForKey:#"textField1"];
[super viewWillAppear:YES];
}
Implement this in each VC, and you're good to go.