Map Kit with Annotations in iPhone

Hi Friends,

Hello readers in today’s post we will see how to add annotations to the map. 

Design Phase: The design phase is quite simple we will be showing a pin onto our map just like the once present in google map. Here’s a view at our final output in case you are getting confused.

Step 1: In order to display an annotation we have to first create a NSObject class give it an appropriate name and then add some piece of code to it, but before even doing that make sure you have added the map kit framework to your project. Coming to the coding section now.

Create a class which inherits from NSObject and save it with the name LocationwithAnnotations,

 import the map kit framework and add a protocol to your class called MKAnnotation here’s how the entire code looks like

#import <Foundation/Foundation.h>

//import the map kit header file

#import <MapKit/MapKit.h>

@interface LocationwithAnnotation : NSObject <MKAnnotation> {

}

@end

MKAnnotation is a protocol which is used to provide annotation related information in the map view.

Step 2: Select the LocationwithAnnotation.m file and add this piece of code, you can always refer the MKAnnotation in the documentation in order to get its method.

@implementation LocationwithAnnotation

- (NSString *)title

{

return @"Current Location";

}

- (NSString *)subtitle

{

return @"Here i am";

}

-(CLLocationCoordinate2D) coordinate

{

CLLocationCoordinate2D coord = {19.12,73.02};

return coord;

}

@end

Code Explanation: In the documentation for MKAnnotation protocol there are two methods and one property.

The methods are quite simple they just display the title and subtitle that will be appearing once the user hits the annotation. 

The property says that "fine you wana display an annotation then tell me the location where you want to place the annotation" that’s all and since it’s a read only property I have added my own method to it so that it knows the location where to place the annotation.

Step 3: Create a map interface by referring my earlier map kit post  and then select the the .h file of myviewController and import the LoacationwithAnnotation header file and declare its object in the .h file

#import <UIKit/UIKit.h>

#import <MapKit/MapKit.h>

#import "LocationwithAnnotation.h"

@interface myviewController : UIViewController {

MKMapView *mymapview;

LocationwithAnnotation * mylocation;

}

@end

now in the .m file of myviewController select the init method and allocate memory for the LocationwithAnnotation object.

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {

    if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {

        // Custom initialization

mylocation = [[LocationwithAnnotation alloc]init];

    }

    return self;

}

now the final step is to add the annotation to the object of the MKMapView in the loadView method

[mymapview addAnnotation:mylocation];

Step 4: Carry out the basics steps to show the view into the iPhone simulator window by selecting the AppDelegate.m file and then press build and Go

Step 5: You will get the below output.

Extra Points: In the above example i have hard coded the coordinates and if you want to display the coordinates by letting the user specify the values then you can do this by adding some parameters to the init method of the NSObject class that you will be making in this case LocationwithAnnotations.