Initializing and passing values between ViewControllers

Question

I have two UIViewControllers: TimerViewController and EfficiencyViewController (For simplicity's sake, we will call them TVC and EVC)

I am trying to pass certain values (2 NSString objects, 1 NSTimeInterval)from TVC to EVC when a button is pressed. EVC needs to be intialized and pop up upon pressing the button. Overall, I have tried two methods.

1. Directly passing the values (In TVC)

     UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
EfficiencyViewController *efficiencyViewController = [storyboard instantiateViewControllerWithIdentifier:@"EfficiencyView"];
efficiencyViewController.category = _categoryLabel.text;
efficiencyViewController.desc = _descriptionTextField.text;
efficiencyViewController.duration = [_timer getInterval];
efficiencyViewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentViewController:efficiencyViewController animated:YES completion:NULL];

Problem: When I instantiate EVC, the values I held in TVC are reset, so basically no data is passed. (I think this is because EVC actually pops up on the screen)

2. Building a custom init method

TVC

EfficiencyViewController *efficiencyViewController = [[EfficiencyViewController alloc] initWithName:_categoryLabel.text desc:_descriptionTextField.text duration:[_timer getInterval]];
[self presentViewController:efficiencyViewController animated:YES completion:NULL];

EVC initWithName method implementation

- (id)initWithName:(NSString *)category desc:(NSString *)theDesc duration:(NSTimeInterval)theDuration {
// self = [super initWithNibName:@"EfficiencyViewController" bundle:nil];
if (self != nil) {
    _category = category;
    _desc = theDesc;
    _duration = theDuration;
}
return self;
}

Problem: The values are simply not being passed. And also in this way, EVC is missing some major components, such as a button and a text label.

I'm not sure that [Passing Data between View Controllers](http://stackoverflow.com/q/5210535/643383) is exactly a duplicate, but it should help. Half your problem seems to stem from from instantiating your view controllers yourself. It's possible to do that of course, but you're swimming upstream. @NRitH's suggestion to use segues is the preferred route. — Caleb, Feb 13 '17 at 21:20

score 1 · Accepted Answer · answered Feb 13 '17 at 21:12

1

If you have these in a storyboard, you should be using a storyboard segue, and in TVC's prepareForSegue(), you get the destination view controller (i.e. EVC) from the segue object, and that's where you set EVC's properties.

answered Feb 13 '17 at 21:12

NRitH

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score 0 · Answer 2 · edited May 23 '17 at 11:46

0

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main"
 bundle:nil]; EfficiencyViewController *efficiencyViewController =
 [storyboard
instantiateViewControllerWithIdentifier:@"EfficiencyView"];
efficiencyViewController.category = _categoryLabel.text;
efficiencyViewController.desc = _descriptionTextField.text;
efficiencyViewController.duration = [_timer getInterval];
efficiencyViewController.modalTransitionStyle =
 UIModalTransitionStyleCoverVertical;

Use self instead of _, see this link https://stackoverflow.com/a/30901681/4912468

edited May 23 '17 at 11:46

Community

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answered Feb 13 '17 at 18:27

Pabel de Jesus Nuñez Landestoy

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Hm.. I see. The reason I chose to use _, is because of readability. Wouldn't using self. hinder the readability of your code? What's your opinion? – besnuj Feb 15 '17 at 04:24

Initializing and passing values between ViewControllers

2 Answers2