Finding Path/Route Between two points on MapKit in iPhone

http://tricksni.blogspot.com/2012/12/finding-pathroute-between-two-points-on.html

Below is the code to finds path & draws line between two locations.

To implement below class:

_mapRecord = [[PSMapDirection alloc] initWithFrame:CGRectMake(0.0, 49.0, 320.0, 411.0)];
[self.view addSubview:_mapRecord];

MapDirection.h

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

@interface MapDirection : UIView<MKMapViewDelegate>
{
MKMapView* mapView;
NSArray* routes;
BOOL isUpdatingRoutes;
}

-(void) showRouteFrom: (MKAnnotation*) f to:(MKAnnotation*) t;

@end


MapDirection.m

#import "MapDirection.h"

@interface MapDirection()
-(NSArray*) calculateRoutesFrom:(CLLocationCoordinate2D) from to: (CLLocationCoordinate2D) to;
-(void) centerMap;

@end

- (id) initWithFrame:(CGRect) frame
{
self = [super initWithFrame:frame];
if (self != nil)
{
mapView = [[MKMapView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
mapView.showsUserLocation = NO;
[mapView setDelegate:self];
[self addSubview:mapView];
}
return self;
}

- (NSMutableArray *)decodePolyLine: (NSMutableString *)encoded
{
[encoded replaceOccurrencesOfString:@"\\\\" withString:@"\\" options:NSLiteralSearch range:NSMakeRange(0, [encoded length])];
NSInteger len = [encoded length];
NSInteger index = 0;
NSMutableArray *array = [[NSMutableArray alloc] init];
NSInteger lat=0;
NSInteger lng=0;
while (index < len)
{
NSInteger b;
NSInteger shift = 0;
NSInteger result = 0;
do
{
b = [encoded characterAtIndex:index++] - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
NSInteger dlat = ((result & 1) ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do
{
b = [encoded characterAtIndex:index++] - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
NSInteger dlng = ((result & 1) ? ~(result >> 1) : (result >> 1));
lng += dlng;
NSNumber *latitude = [[NSNumber alloc] initWithFloat:lat * 1e-5];
NSNumber *longitude = [[NSNumber alloc] initWithFloat:lng * 1e-5];
//printf("[%f,", [latitude doubleValue]);
//printf("%f]", [longitude doubleValue]);
CLLocation *loc = [[CLLocation alloc] initWithLatitude:[latitude floatValue] longitude:[longitude floatValue]];
[array addObject:loc];
}
return array;
}

-(NSArray*) calculateRoutesFrom:(CLLocationCoordinate2D) f to: (CLLocationCoordinate2D) t
{
NSString* saddr = [NSString stringWithFormat:@"%f,%f", f.latitude, f.longitude];
NSString* daddr = [NSString stringWithFormat:@"%f,%f", t.latitude, t.longitude];

NSString* apiUrlStr = [NSString stringWithFormat:@"http://maps.google.com/maps?output=dragdir&saddr=%@&daddr=%@", saddr, daddr];
NSURL* apiUrl = [NSURL URLWithString:apiUrlStr];
//NSLog(@"api url: %@", apiUrl);
NSError* error = nil;
NSString *apiResponse = [NSString stringWithContentsOfURL:apiUrl encoding:NSASCIIStringEncoding error:&error];
NSString *encodedPoints = [apiResponse stringByMatching:@"points:\\\"([^\\\"]*)\\\"" capture:1L];
return [self decodePolyLine:[encodedPoints mutableCopy]];
}

-(void) centerMap
{
MKCoordinateRegion region;
CLLocationDegrees maxLat = -90.0;
CLLocationDegrees maxLon = -180.0;
CLLocationDegrees minLat = 90.0;
CLLocationDegrees minLon = 180.0;
for(int idx = 0; idx < routes.count; idx++)
{
CLLocation* currentLocation = [routes objectAtIndex:idx];
if(currentLocation.coordinate.latitude > maxLat)
maxLat = currentLocation.coordinate.latitude;
if(currentLocation.coordinate.latitude < minLat)
minLat = currentLocation.coordinate.latitude;
if(currentLocation.coordinate.longitude > maxLon)
maxLon = currentLocation.coordinate.longitude;
if(currentLocation.coordinate.longitude < minLon)
minLon = currentLocation.coordinate.longitude;
}
region.center.latitude = (maxLat + minLat) / 2.0;
region.center.longitude = (maxLon + minLon) / 2.0;
region.span.latitudeDelta = 0.01;
region.span.longitudeDelta = 0.01;

region.span.latitudeDelta = ((maxLat - minLat)<0.0)?100.0:(maxLat - minLat);
region.span.longitudeDelta = ((maxLon - minLon)<0.0)?100.0:(maxLon - minLon);
[mapView setRegion:region animated:YES];
}

-(void) showRouteFrom: (MKAnnotation*) f to:(MKAnnotation*) t
{
if(routes)
{
[mapView removeAnnotations:[mapView annotations]];
}

[mapView addAnnotation:f];
[mapView addAnnotation:t];

routes = [self calculateRoutesFrom:f.coordinate to:t.coordinate];
NSInteger numberOfSteps = routes.count;

CLLocationCoordinate2D coordinates[numberOfSteps];
for (NSInteger index = 0; index < numberOfSteps; index++)
{
CLLocation *location = [routes objectAtIndex:index];
CLLocationCoordinate2D coordinate = location.coordinate;
coordinates[index] = coordinate;
}
MKPolyline *polyLine = [MKPolyline polylineWithCoordinates:coordinates count:numberOfSteps];
[mapView addOverlay:polyLine];
[self centerMap];
}

#pragma mark MKPolyline delegate functions
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
MKPolylineView *polylineView = [[MKPolylineView alloc] initWithPolyline:overlay];
polylineView.strokeColor = [UIColor purpleColor];
polylineView.lineWidth = 5.0;
return polylineView;
}

@end

Sample Map Route for starting points - "41.967659,-87.627869" and destination points - "41.574361,-91.083069"