Ray Wenderlich's MapKit Tutorial

MyLocation.m

//
//  MyLocation.m
//  MapTutorial
//
//  Created by David Ohayon on 12/22/12.
//  Copyright (c) 2012 David Ohayon. All rights reserved.
//

#import "MyLocation.h"
#import <AddressBook/AddressBook.h>

@interface MyLocation()

@property (nonatomic, copy) NSString* name;
@property (nonatomic, copy) NSString* address;
@property (nonatomic, assign) CLLocationCoordinate2D theCoordinate;

@end

@implementation MyLocation

- (id)initWithName:(NSString *)name address:(NSString *)address coordinate:(CLLocationCoordinate2D)coordinate{
    if (self = [super init]) {
        if([name isKindOfClass:[NSString class]]){
            self.name = name;
        } else{
            self.name = @"Unknown Charge";
        }
        self.address = address;
        self.theCoordinate = coordinate;
    }
    return self;
}

- (NSString*)title{
    return _name;
}

- (NSString*)subtitle{
    return _address;
}

- (CLLocationCoordinate2D)coordinate{
    return _theCoordinate;
}

- (MKMapItem*)mapItem{
    NSDictionary* addressDict = @{
        (NSString*) kABPersonAddressStreetKey: _address
    };
    MKPlacemark* placemark = [[MKPlacemark alloc] initWithCoordinate:self.coordinate addressDictionary:addressDict];
    
    MKMapItem* mapItem = [[MKMapItem alloc] initWithPlacemark:placemark];
    mapItem.name = self.title;
    
    return mapItem;
}

@end

ViewController.m

//
//  ViewController.m
//  MapTutorial
//
//  Created by David Ohayon on 12/22/12.
//  Copyright (c) 2012 David Ohayon. All rights reserved.
//

#import "ViewController.h"
#import "ASIHTTPRequest.h"
#import "MyLocation.h"
#define METERS_PER_MILE 1609.344
@interface ViewController ()

@end

@implementation ViewController

- (void)plotCrimePositions:(NSData*)responseData{
    for (id<MKAnnotation> annotation in _mapView.annotations) {
        [_mapView removeAnnotation:annotation];
    }
    
    NSDictionary* root = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:nil];
    NSArray* data = [root objectForKey:@"data"];
    
    for (NSArray* row in data) {
        NSNumber* latitute = row[21][1];
        NSNumber* longitude = row [21][2];
        NSString* crimeDescription = row[17];
        NSString* address = row[13];
        
        CLLocationCoordinate2D coordinate;
        coordinate.latitude = latitute.doubleValue;
        coordinate.longitude = longitude.doubleValue;
        MyLocation* annotation = [[MyLocation alloc] initWithName:crimeDescription address:address coordinate:coordinate];
        [_mapView addAnnotation:annotation];
    }
}

- (IBAction)refreshTapped:(id)sender{
    MKCoordinateRegion mapRegion = [_mapView region];
    CLLocationCoordinate2D centerLocation = mapRegion.center;
    
    NSString* jsonFile = [[NSBundle mainBundle] pathForResource:@"command" ofType:@"json"];
    NSString* formatString = [NSString stringWithContentsOfFile:jsonFile encoding:NSUTF8StringEncoding error:nil];
    NSString* json = [NSString stringWithFormat:formatString, centerLocation.latitude, centerLocation.longitude, 0.5*METERS_PER_MILE];
    
    NSURL* url = [NSURL URLWithString:@"http://data.baltimorecity.gov/api/views/INLINE/rows.json?method=index"];
    
    ASIHTTPRequest* _request = [ASIHTTPRequest requestWithURL:url];
    __weak ASIHTTPRequest* request = _request;
    
    request.requestMethod = @"POST";
    [request addRequestHeader:@"Content-Type" value:@"application/json"];
    [request appendPostData:[json dataUsingEncoding:NSUTF8StringEncoding]];
    [request setDelegate:self];
    [request setCompletionBlock:^{
        NSString* responseString = [request responseString];
        NSLog(@"Response: %@", responseString);
    }];
    [request setFailedBlock:^{
        NSError* error = [request error];
        NSLog(@"Error %@", error.localizedDescription);
    }];
    
    [request startAsynchronous];
    [self plotCrimePositions:request.responseData];
}

- (void) viewWillAppear:(BOOL)animated{
    CLLocationCoordinate2D zoomLocation;
    zoomLocation.latitude = 39.281516;
    zoomLocation.longitude = -76.580806;
    
    MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(zoomLocation, 0.5*METERS_PER_MILE, 0.5* METERS_PER_MILE);
    
    [_mapView setRegion:viewRegion animated:YES];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end