iOS 5 Programming Cookbook

6.2. Handling the Events of a Map View

Problem

You want to handle various events that a map view can send to its delegate.

Solution

Assign a delegate object, which conforms to the MKMapViewDelegate protocol, to the delegate property of an instance of the MKMapView class:

/* Create a map as big as our view */
self.myMapView = [[MKMapView alloc]
                  initWithFrame:self.view.bounds];

/* Set the map type to Satellite */
self.myMapView.mapType = MKMapTypeSatellite;

self.myMapView.delegate = self;

self.myMapView.autoresizingMask =
  UIViewAutoresizingFlexibleWidth |
  UIViewAutoresizingFlexibleHeight;

/* Add it to our view */
[self.view addSubview:self.myMapView];

This code can easily run in the viewDidLoad method of a view controller object that has a property named MapView of type MKMapView:

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

@interface Handling_the_Events_of_a_Map_ViewViewController
           : UIViewController <MKMapViewDelegate>

@property (nonatomic, strong) MKMapView *myMapView;

@end

Discussion

The delegate object of an instance of the MKMapView class must implement the methods defined in the MKMapViewDelegate protocol in order to receive various messages from the map view and, as we will see later, to provide information to the map view. Various methods are defined in the MKMapViewDelegate protocol, such as the mapViewWillStartLoadingMap: method that will get called in the delegate object whenever the map loading process starts. Bear in mind that a delegate for a map view is not a required ...