Issue with sending data from one view to another. - ios

Question

I am trying to transfer a users location from a screen where I allow the user to take a picture to another view where I have a map. The purpose of this is to tag the image location on the map and have that be related with the image. The current code I have for launching the ability to take an image is as follows:
- (IBAction)takePhoto:(UIButton *)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:picker animated:YES completion: NULL];
}
-(void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
// Pin location as annotation on map
NSString *dateString = [NSDateFormatter localizedStringFromDate:[NSDate date]
dateStyle:NSDateFormatterShortStyle
timeStyle:NSDateFormatterFullStyle];
MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
MKUserLocation *userLocation = [[MKUserLocation alloc] init];
MKMapView *mapView = [[MKMapView alloc] init];
point.coordinate = userLocation.coordinate;
point.title = #"Picture Entry";
point.subtitle = dateString;
[mapView addAnnotation:point];
// Close camera and go back to home screen
[self dismissModalViewControllerAnimated:YES];
}
I'm new to iOS programming and I'm not sure how to pass the location back to my mapView, and I believe in this code I'm just initializing a new map to save the annotation to, and thats not what I want obviously.
MapViewController.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#interface MapViewController : UIViewController <MKMapViewDelegate>
#property (strong, nonatomic) IBOutlet MKMapView *mapView;
#end
MapViewController.m
#import "MapViewController.h"
#interface MapViewController ()
#end
#implementation MapViewController
#synthesize mapView;
- (void)viewDidLoad
{
// Get user location
mapView.showsUserLocation = YES;
self.mapView.delegate = self;
}
// Update map based on user location and zoom to area
- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:
(MKUserLocation *)userLocation
{
mapView.centerCoordinate = userLocation.location.coordinate;
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(userLocation.coordinate, 800, 800);
[self.mapView setRegion:[self.mapView regionThatFits:region] animated:YES];
}
#end
This is what I have for now, and I'm at a loss for how to handle this.

Answer 1

I believe in this code I'm just initializing a new map to save the annotation to, and thats not what I want obviously.
You're right -- you're creating a new map and adding the annotation to that object. (Also, you're not creating the map view correctly -- you should use -initWithFrame: because that's a designated initializer for views.)
You should rethink your approach. What you seem to be trying to do is to modify the map view of one view controller (your MapViewController) from a different view controller (assuming that the image picker delegate is some view controller other than MapViewController). A view controller should be in charge of its own views but shouldn't mess with the views of another view controller. Also, adding the annotation that way means that you're effectively storing the location in the map view, and you should avoid using views to store data.
Instead, think about where you should really be saving your data. The M in MVC is for model, i.e. that part of your app that manages the data. As you can see in the acronym, it should be separate from your view(s) and from your controller(s). The model is something that your various view controllers can all use to get the information they need, and having one makes your app simpler because you don't have to worry as much about sending data back and forth between view controllers. The model doesn't have to be anything terribly complicated -- for very simple apps that mainly manage a list of items, even an plain old NSArray or NSSet could serve as a data model. Give each view controller that needs it a reference to the model, or to part of the model.
With that in mind, the right way to fix your app is to have some sort of data model. The image picker delegate should update the map by adding information to the model. The map view controller should be in charge of adding annotations to the map view, and it can do that based on the information in the model.