Add objects to an NSMutableArray in my base view controller from a second view controller, ios

Question

I have been searching all morning how to do this. I have 2 View Controllers. From the root View Controller (ViewControllerA - which is a table view controller) you can go push to the second view controller (ViewControllerB).

In the ViewControllerB, there are two fields: contacts & textBody. When the user is done they can click on "Add". This will then go back to ViewControllerA. What I am trying to do now, is for every time that process occurs, all the information from ViewControllerB the user just added goes into a cell in ViewControllerA. The user can then add as many cells as they like.

What I can't do however, is get the information across the view controllers. I have been looking all morning at using the app delegate, singletons??, protocols, sharing properties, etc! But I am still stuck.

What I want to do, but can't, is for every time the user clicks "Add" on ViewControllerB, contacts & texts are put into an array. This array is then put into another array which holds all the smaller arrays which the user has created? If you have an ideas, or links to similar/sample code or tutorials, that would be much appreciated!

icodebuster · Accepted Answer · 2013-06-23 06:03:10Z

2

Try this using the delegate method as follows

Download Sample Project with XIBs

Download Sample Project With Storyboard

ParentViewController.h

#import <UIKit/UIKit.h>

@interface ParentViewController : UIViewController {    
    NSMutableArray *dataArray;
}
- (void)passData:(NSMutableArray *)array;
@end

ParentViewController.m

#import "ParentViewController.h"
#import "ChildViewController.h"

@implementation ParentViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Initialise the mutable array.
    dataArray = [[NSMutableArray alloc] init];
}

- (IBAction)btnGoToSecondView:(id)sender {
    ChildViewController *secondVC = [[ChildViewController alloc] initWithNibName:@"ChildViewController" bundle:nil];
    secondVC.delegate = self;
    [self presentViewController:secondVC animated:YES completion:nil];
}

- (void)passData:(NSMutableArray *)array {
    [dataArray addObject:array];
    NSLog(@"Data Passed = %@",dataArray);
}
@end

ChildViewController.h

#import <UIKit/UIKit.h>
#import "ParentViewController.h"

@class ParentViewController;

@interface ChildViewController : UIViewController {    
    NSMutableArray *tempArray;
}

@property (strong, nonatomic) IBOutlet UITextField *txtContact;
@property (strong, nonatomic) IBOutlet UITextField *txtTextBody;
@property(nonatomic, assign) ParentViewController *delegate;
@end

ChildViewController.m

@implementation ChildViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Initialise the mutable array.
    tempArray = [[NSMutableArray alloc] init];
}

- (IBAction)btnPassDataBack:(id)sender {
    if([self.delegate respondsToSelector:@selector(passData:)]) {

        [tempArray addObject:_txtContact.text];
        [tempArray addObject:_txtTextBody.text];

        [self.delegate passData:tempArray];
    }
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)viewDidUnload {
    [self setTxtContact:nil];
    [self setTxtTextBody:nil];
    [super viewDidUnload];
}
@end

With Storyboard

If you are using storyboard then create a ParentViewController segue ChildViewController and give it a identifier in my sample it showChildView

Then use the following code to set the delegate

// Calling the segue to go to the child view and setting up the delegate.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showChildView"]) {
        ChildViewController *childVC = segue.destinationViewController;
        childVC.delegate = self;
    }
}

Then to dismiss back to the ParentViewController use the following code (from my sample)

- (IBAction)btnPassDataBack:(id)sender {
    if([self.delegate respondsToSelector:@selector(passData:)]) {

        [tempArray addObject:_txtContact.text];
        [tempArray addObject:_txtTextBody.text];

        [self.delegate passData:tempArray];
    }
    [self.navigationController popToRootViewControllerAnimated:YES];
}

edited Jun 23, 2013 at 6:03

answered Jun 22, 2013 at 4:04

icodebuster

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4 Comments

icodebuster Over a year ago

@falky try the above code. its working as per your need. You can directly download and check the sample code attached

falky Over a year ago

That was really helpful! thank you. The only thing is that I don't know how to implement it with storyboard (I'm not using nibs). Also, an error appeared in the childViewController.h file on this line: @property(nonatomic, assign) ParentViewController *delegate; And I'm not sure how to fix it. Thanks for your help though

falky Over a year ago

A sample with storyboard would be great. I'll accept it as the answer too. Thanks very much! Firstly I'm using a UINvaigation controller, secondly, the error for the property is: "Parse issue, unknown type name 'ViewControllerA'"... Does it matter that it's a tableViewController?

icodebuster Over a year ago

@falky check the sample project. I have added storyboard sample code as well as the explanation.

Dan · Accepted Answer · 2013-06-22 02:40:27Z

I would recommend using a singleton instance of your NSMutableDictionary as they have bailed me out of your exact situation multiple times (including custom frameworks and UITabBarControllers). Here is an example I'm currently using to implement a singleton. This methodology is also ARC-safe as well

mySingleton.h

#import <Foundation/Foundation.h>

@interface mySingleton : NSObject {

}
+ (NSMutableDictionary *) myMutableDict;

@end

mySingleton.m

#import "mySingleton.h"

@implementation mySingleton

+ (NSMutableDictionary *)myMutableDict
{
    static NSMutableDictionary *singletonInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        singletonInstance = [[NSMutableDictionary alloc]init];

    });
    return singletonInstance;
}

@end

As long as you include mySingleton.h in all of your view controllers you can access the data via [mySingleton myMutableDict]. For example: [[mySingleton myMutableDict] setObject:myObject forKey:myKey];

Good luck!

Khanh Nguyen · Accepted Answer · 2013-06-22 03:11:59Z

If the information is really "global" - it has only one instance across the whole app - then you should create a singleton as DB80Buckeye suggested.

If the information is something that truly belongs to ViewController1 and you want it to be modified in ViewController2 (ie ViewController2 is really part of ViewController1, it just happens to be on another screen), then you should pass that as part of the constructor of ViewController2.

-(void)view_controller_1_that_push_view_controller_2_onto_the_stack {
     ViewController2* vc2 = [[ViewController2 alloc] initWithInformation:your_information];
     [self.navigationController pushViewController:vc2 animated:YES];
}

@interface ViewController2 

-(id)initWithInformation:(YourInformationClass*)info;

@end

Another way is to use notifications.

Amro · Accepted Answer · 2013-06-22 03:30:22Z

There are two ways to go here. The standard pattern for doing this is delegation. You don't need a singleton. ViewControllerA manages and lists your data. ViewControllerB doesn't need to know anything about all of that data so there's no reason to expose it via a singleton, etc.

Create a delegate protocol in ViewControllerB's header file. Something like this:

@protocol ViewControllerBDelegate
- (void)addContact:(NSString *)contact withBody:(NSString *)textBody;
@end

Now, specify that ViewControllerA will implement the delegate protocol in its header:

@interface ViewControllerA : UIViewController <ViewControllerBDelegate>

Don't forget to import ViewControllerB.h at the top of ViewControllerA's header.

In ViewControllerA's implementation, implement the delegate method you specified in the protocol:

- (void)addContact:(NSString *)contact withBody:(NSString *)textBody {
    [self.someArray addObject:[[SomeObject alloc] initWithContact:contact body:textBody]];
    [self.tableView reloadData];
}

That's obviously just an example -- not sure how you're managing your data structure and it's probably better to insert the cell someplace that makes sense.

Declare a delegate reference in ViewControllerB's header:

@property (weak, nonatomic) id<ViewControllerBDelegate> delegate;

When you present ViewControllerB, set ViewControllerA as the delegate.

ViewControllerB *b = [[ViewControllerB alloc] init...];
b.delegate = self;

In the selector triggered by the add button in ViewControllerB, call back on the delegate before popping the view controller off the navigation stack:

[self.delegate addContact:contact withBody:text];

where contact and text are the values the user entered.

One could also use a block instead of a delegate but the principle is the same -- have the second view controller only be responsible for taking input, in your case, and pass it back to the view controller managing the data.

stosha · Accepted Answer · 2013-06-22 04:27:48Z

1

Alternatively for delegate suggest using the following: ViewControllerA.h:

 @property (nonatomic, strong) ViewControllerB* viewControllerB;

In ViewControllerA.m

if (!self.viewControllerB)
{
     self.viewControllerB = [[ViewControllerB alloc] initWithNibName: @"ViewControllerBr"                                                                                                 bundle: nil];      
}
[self.navigationController pushViewController: self.viewControllerB
                                     animated: YES];

...

- (void) viewWillAppear: (BOOL) animated

   if (self.viewControllerB)
   {
       NSString* contact = self.viewControllerB.contact;
       NSLog(@"%@", contact);
   }

...

edited Jun 22, 2013 at 4:27

answered Jun 22, 2013 at 3:53

stosha

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