Pass data between view controller

Question

I'm trying to pass an object (PFObject) from an view controller to another,

-(void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
    RestauCardViewController *restauCard = [[RestauCardViewController alloc]init];
    RestaurantAnnotation *restoAnnotation = (RestaurantAnnotation *)view.annotation;

    restauCard.restaurant = restoAnnotation.restaurant;
    [self performSegueWithIdentifier:@"segueToCard" sender:nil];
}

When I try to display the object in the other view controller I got null:

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

@interface RestauCardViewController : UIViewController

@property(nonatomic) PFObject *restaurant;

@end

This is my viewDidLoad function

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    NSLog(@"The restaurant name is : %@",_restaurant[@"nom"]);
}

See http://stackoverflow.com/questions/14805954/mkannotationview-push-to-view-controller-when-detaildesclosure-button-is-clicked. Instead of using a property or ivar to store the selection, pass the annotation `view` as `sender`. It makes the code more self-contained and uses functionality already provided by the api. — , May 05 '15 at 11:00

score 2 · Answer 1 · answered May 05 '15 at 09:09

2

You have to set the restaurent inside the UIViewController method "prepareSegue...". It's called after you performeSegueWithIdentifier, so the destination controller is accessible and you can test the segue.identifier and set the restaurent to the controller.

Example :

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    if ([segue.identifier isEqualToString:@"segueRestaurentDetails"]) {

        RestauCardViewController *destController = (RestaurentDetailsViewController *)segue.destinationViewController;
        destController.restaurant = (RestaurantAnnotation *)view.annotation;
}

answered May 05 '15 at 09:09

David Ansermot

6,052
8
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Thank you, but how i can access to the view from the prepareForSegue method ? – Aissa El Ouafi May 05 '15 at 09:30
You can store it before calling "performeSegueWithIdentifier" inside a private variable like `@property (nonatomic, strong) UIView *viewToDisplay;` . Then you get it like `(RestaurantAnnotation *)_viewToDisplay.annotation;` – David Ansermot May 05 '15 at 09:32
Don't use a property for this, it's accessible from the outside of the class which you don't need. Use an ivar instead ; see my answer for more details. Both our answers are fairly close to each other – Gil Sand May 05 '15 at 09:35
Private properties declared in `@interaface` in **.m** are not accessible from outside. ivar are no more needed... update to the last objective-c practices please. – David Ansermot May 05 '15 at 09:42

score 2 · Accepted Answer · answered May 05 '15 at 09:34

You need to use -prepareForSegue to manage this situation, and you'll need an iVar to keep the restaurant name.

So in the top of your map's .m file, add an ivar NSString

@implementation yourViewController{

    NSString *sRestName;   //This is empty until the user selects a restaurant

}

-(void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
    sRestName = //Set the name of your restaurent here, it's just a string. 
                //You could set any other type of object (a restaurent object or a PFOjbect or anything, 
               //just change the ivar accordingly
    [self performSegueWithIdentifier:@"segueToCard" sender:nil];
}

What you're going to do is replace your old code with the code just above, you just need to perform the segue to call the following method.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { 

    if([segue.identifier isEqualToString:@"fromHomeToList"]){
        RestauCardViewController *vc = (RestauCardViewController*)segue.destinationViewController;
        vc.restaurant = sRestName; //here you're just giving the property of the new controller the content of your ivar. 
}

That way you can pass an object from your map tap to your next controller. You're also sure it will never be nil because the user tapped it ; if it was nil, well, he couldn't have tapped it in the first place !

Note that I assumed you were using a string for your restaurant name, but if you change the ivar on the top, you can use anything you want, as long as you can retrieve it from tapping on the map. If you can't, I need more details to walk you through another solution.

Ask me if you have any quesiton, otherwise this should work !

Thank you verry much thats work :) – Aissa El Ouafi May 05 '15 at 09:37 — Aissa El Ouafi, May 05 '15 at 09:37

score 0 · Answer 3 · answered May 05 '15 at 09:11

0

Implement prepareForSegue:sender: method in ViewController

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if([segue.identifier isEqualToString:@"segueToCard"]) {
        RestauCardViewController *controller = (RestauCardViewController *)segue.destinationViewController;
        controller.restaurant = (RestaurantAnnotation *)view.annotation;
    }
}

answered May 05 '15 at 09:11

Elliot Li

452
1
5
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thank you, but i get this error : controller.restaurant = (RestaurantAnnotation *)view.annotation; Use of undeclared identifier view – Aissa El Ouafi May 05 '15 at 09:19
how you declare `view` in your code? – Elliot Li May 05 '15 at 09:21
here : -(void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control { [self performSegueWithIdentifier:@"segueToCard" sender:nil]; } – Aissa El Ouafi May 05 '15 at 09:23
Boyi Li your code is wrong, you haven't declared view in your prepareforsegue method, this won't compile. – Gil Sand May 05 '15 at 09:26
How I can do to declare the view in my prepareforsefue method ? – Aissa El Ouafi May 05 '15 at 09:27
Is that possible that you get the MKAnnotation directly? Or you could create a local temporary variable – Elliot Li May 05 '15 at 09:28
Thank you verry much you saved my day :-) – Aissa El Ouafi May 05 '15 at 09:34

Pass data between view controller

3 Answers3