How to send value from viewControllerA to viewControllerB?

Question

A UIButton with title ---> Free Coins - Press <---- on viewControllerA is pressed.

viewControllerA:

- (IBAction)triggerVideo
{
    [AdColony playVideoAdForZone:@"HIDDEN-CODE-PRIVACY" withDelegate:nil
        withV4VCPrePopup:YES andV4VCPostPopup:YES];
}

50 coins are gained when it's clicked:

// Get currency balance from persistent storage and display it
- (void)updateCurrencyBalance
{
    NSNumber* wrappedBalance = [[NSUserDefaults standardUserDefaults]
        objectForKey:kCurrencyBalance];
    NSUInteger balance = wrappedBalance && [wrappedBalance isKindOfClass:
        [NSNumber class]] ? [wrappedBalance unsignedIntValue] : 0;
    [currencyLabel setText:[NSString stringWithFormat:@"%u", balance]];
}

But these coins must only show up on viewControllerB, on the label called lblpts. Or at least show up on both as the same values!

I've tried to use ints: e.g. int point, and objectForKey:@"point", e.g.:

savedStock = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

nPoint = [[savedStock objectForKey:@"point"] intValue];
[_lblpts setText:[NSString stringWithFormat:@"%d",nPoint]];

But it seems, I can't make the balance appear only on the viewControllerB label!

What's in the file at `path`? What's in `savedStock` after you init it? — Phillip Mills, Apr 24 '14 at 12:07

score 1 · Accepted Answer · edited May 06 '14 at 15:11

1

You need to have a property variable in viewControllerB and while pushing viewControllerB initialize that variable with points.

If you are using storyboard then:

[self performSegueWithIdentifier:@"SegueB" sender:self];

In prepareForSegue method update the property variable with latest points.

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"SegueB"]) {
        DetailVCB *detailB = (DetailVCB *)segue.destinationViewController;
        detailB.points = 50; // the variable which has latest points.
    }
}

If you are using XIB then you can achieve it adding this in ViewControllerA.m:

ViewB *ScreenB = [[[ViewB alloc]initWithNibName:@"ViewBNib" bundle:nil]
    autorelease];
ScreenB.points = balance; //balance is the variable having latest points
[self.navigationController pushViewController:ScreenB animated:YES];

In ViewControllerB.h file add the property declaration as:

@property (nonatomic, assign) NSInteger points;

In ViewControllerB.m file:

- (void)viewDidLoad
{
    NSString *str = [NSString stringWithFormat: @"%d", self.points];
    [self.pointsLbl setText:str];
}

edited May 06 '14 at 15:11

Lebyrt

1,376
1
9
18

answered Apr 24 '14 at 12:04

user2071152

1,161
1
11
25

Could you please give an example? @property IBOutlet UILabel* currencyLabel; ? B to B or did you mean A to B? – Jking Apr 24 '14 at 12:05
No I'm not using story board! – Jking Apr 24 '14 at 12:11
You can also use NSUserDefault to store and retrieve the same in ViewControllerB. Are you using XIB? – user2071152 Apr 24 '14 at 12:11
detailB.points = balance; // the variable which has latest points? because the coins are coming from a different server! – Jking Apr 24 '14 at 12:12
yes, you can use detailB.points = balance. – user2071152 Apr 24 '14 at 12:13
I have edited my answer to reflect for XIB also – user2071152 Apr 24 '14 at 12:15
Should I edit some of the code highlight in blue! Should I implement this into the ViewController B, where the coins will show? – Jking Apr 24 '14 at 12:17
You only need to declare a property variable in ViewControllerB.h file and while pushing ViewControllerB file update the variable with actual value. In ViewDidLoad() method of ViewControllerB using this variable update the UILabel. – user2071152 Apr 24 '14 at 12:22
I'm getting an error on auto release – Jking Apr 24 '14 at 15:03
Didnt work, even if you wanted it to – Jking Apr 24 '14 at 16:09

nikhil84 · Answer 2 · 2014-05-07T07:00:47.723

0

You could use a custom delegate method or notification center method for passing data between two view controller's. Also using property is also good way for passing data but if you got a lot of info to pass from one view controller to another then you should go for custom delegate method.

edited May 07 '14 at 07:00

answered Apr 24 '14 at 12:07

nikhil84

3,235
4
22
43

hey much appreciated an example would help too ? – Jking Apr 24 '14 at 12:10
[custom delegate](http://www.alexefish.com/post/522641eb31fa2a0015000002) check out this example. – nikhil84 Apr 24 '14 at 12:24
@Jking vote up or choosing it as right answer will be appreciated. – nikhil84 May 07 '14 at 07:01

score 0 · Answer 3 · edited May 06 '14 at 15:22

0

This seemed like a forward message passing from viewControllerA to viewControllerB. This can be easily achieved with a simple method below:

Let's say you have a method in viewControllerB:

- (void)UpdatepPoints:(int)pts {
    _point = pts;
}

Now in your viewControllerA, you just have to do something like this:

ViewControllerB *vc = [ViewControllerB alloc] init];
[vc UpdatepPoints:pointshere];

That's all. Use point property of ViewControllerB for getting points.

edited May 06 '14 at 15:22

Lebyrt

1,376
1
9
18

answered Apr 24 '14 at 12:21

but while pushing the ViewControllerB again one more instance of ViewControllerB will be created in that instance the points variable will not be updated. Hence can't do just by allocating an instance of ViewControllerB. – user2071152 Apr 24 '14 at 12:23
Should I make two labels and pass points from one the label in VC-A to the Label in VC-B. Or can I just Make it appear in VC-B with the above code. – Jking Apr 24 '14 at 12:23

score 0 · Answer 4 · edited May 06 '14 at 15:18

You can use NSNotificationCenter to broadcast coin update event. So your code would seems like:

- (IBAction)triggerVideo
{
    [AdColony playVideoAdForZone:@"HIDDEN-CODE-PRIVACY" withDelegate:self
        withV4VCPrePopup:YES andV4VCPostPopup:YES];
}

Note here delegate is self. Now implement delegate like:

- (void)onAdColonyV4VCReward:(BOOL)success currencyName:(NSString*)currencyName
    currencyAmount:(int)amount inZone:(NSString*)zoneID
{       
    NSNumber *number = [[NSNumber alloc] initWithInt:amount];
    [[NSNotificationCenter defaultCenter] postNotificationName:
        @"kCoinUpdateNotification" object:number];
}

And listen for this notification in viewControllerB like this:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(
    updateCurrencyBalance:) name:@"kCoinUpdateNotification" object:nil];

And function implementation goes like:

- (void)updateCurrencyBalance:(NSNotification*)_notifObject
{
    NSNumber *wrappedBalance = [_notifObject object];
    NSUInteger balance = wrappedBalance && [wrappedBalance isKindOfClass:
        [NSNumber class]] ? [wrappedBalance unsignedIntValue] : 0;
    [currencyLabel setText:[NSString stringWithFormat:@"%u", balance]];
}

How to send value from viewControllerA to viewControllerB?

4 Answers4