The following viewDidLoad will (1) set two locations, (2) remove all the previous annotations, and (3) call user defined helper functions (to get route points and draw the route).
-(void)viewDidLoad
{
[super viewDidLoad];
// Origin Location.
CLLocationCoordinate2D loc1;
loc1.latitude = 29.0167;
loc1.longitude = 77.3833;
Annotation *origin = [[Annotation alloc] initWithTitle:@"loc1" subTitle:@"Home1" andCoordinate:loc1];
[objMapView addAnnotation:origin];
// Destination Location.
CLLocationCoordinate2D loc2;
loc2.latitude = 19.076000;
loc2.longitude = 72.877670;
Annotation *destination = [[Annotation alloc] initWithTitle:@"loc2" subTitle:@"Home2" andCoordinate:loc2];
[objMapView addAnnotation:destination];
if(arrRoutePoints) // Remove all annotations
[objMapView removeAnnotations:[objMapView annotations]];
arrRoutePoints = [self getRoutePointFrom:origin to:destination];
[self drawRoute];
[self centerMap];
}
The following is the MKMapViewDelegate method, which draws overlay (iOS 4.0 and later).
/* MKMapViewDelegate Meth0d -- for viewForOverlay*/
- (MKOverlayView*)mapView:(MKMapView*)theMapView viewForOverlay:(id <MKOverlay>)overlay
{
MKPolylineView *view = [[MKPolylineView alloc] initWithPolyline:objPolyline];
view.fillColor = [UIColor blackColor];
view.strokeColor = [UIColor blackColor];
view.lineWidth = 4;
return view;
}
The following function will get both the locations and prepare URL to get all the route points. And of course, will call stringWithURL.
/* This will get the route coordinates from the Google API. */
- (NSArray*)getRoutePointFrom:(Annotation *)origin to:(Annotation *)destination
{
NSString* saddr = [NSString stringWithFormat:@"%f,%f", origin.coordinate.latitude, origin.coordinate.longitude];
NSString* daddr = [NSString stringWithFormat:@"%f,%f", destination.coordinate.latitude, destination.coordinate.longitude];
NSString* apiUrlStr = [NSString stringWithFormat:@"http://maps.google.com/maps?output=dragdir&saddr=%@&daddr=%@", saddr, daddr];
NSURL* apiUrl = [NSURL URLWithString:apiUrlStr];
NSError *error;
NSString *apiResponse = [NSString stringWithContentsOfURL:apiUrl encoding:NSUTF8StringEncoding error:&error];
NSString* encodedPoints = [apiResponse stringByMatching:@"points:\\\"([^\\\"]*)\\\"" capture:1L];
return [self decodePolyLine:[encodedPoints mutableCopy]];
}
The following code is the real magic (decoder for the response we got from the API). I would not modify that code unless I know what I am doing :)
- (NSMutableArray *)decodePolyLine:(NSMutableString *)encodedString
{
[encodedString replaceOccurrencesOfString:@"\\\\" withString:@"\\"
options:NSLiteralSearch
range:NSMakeRange(0, [encodedString length])];
NSInteger len = [encodedString 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 = [encodedString 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 = [encodedString 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("\n[%f,", [latitude doubleValue]);
printf("%f]", [longitude doubleValue]);
CLLocation *loc = [[CLLocation alloc] initWithLatitude:[latitude floatValue] longitude:[longitude floatValue]];
[array addObject:loc];
}
return array;
}
This function will draw a route and will add an overlay.
- (void)drawRoute
{
int numPoints = [arrRoutePoints count];
if (numPoints > 1)
{
CLLocationCoordinate2D* coords = malloc(numPoints * sizeof(CLLocationCoordinate2D));
for (int i = 0; i < numPoints; i++)
{
CLLocation* current = [arrRoutePoints objectAtIndex:i];
coords[i] = current.coordinate;
}
self.objPolyline = [MKPolyline polylineWithCoordinates:coords count:numPoints];
free(coords);
[objMapView addOverlay:objPolyline];
[objMapView setNeedsDisplay];
}
}
The following code will center align the map.
- (void)centerMap
{
MKCoordinateRegion region;
CLLocationDegrees maxLat = -90;
CLLocationDegrees maxLon = -180;
CLLocationDegrees minLat = 90;
CLLocationDegrees minLon = 180;
for(int idx = 0; idx < arrRoutePoints.count; idx++)
{
CLLocation* currentLocation = [arrRoutePoints 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;
region.center.longitude = (maxLon + minLon) / 2;
region.span.latitudeDelta = maxLat - minLat;
region.span.longitudeDelta = maxLon - minLon;
[objMapView setRegion:region animated:YES];
}
I hope this would help someone.
