decode route from google API - objective-c

Question

i am desperately trying to find a way on how to get an Array of all the Coordinates (or a Polyline) from the google API so that I can draw my route on the MKMapView.
( By the way, I don´t want to use the RegexKitLite)
As I found elsewhere, this should be the right way to call for the API.
NSString* apiUrlStr = [NSString stringWithFormat:#"http://maps.google.com/maps?output=dragdir&saddr=%#&daddr=%#", saddr, daddr];
NSURL* apiUrl = [NSURL URLWithString:apiUrlStr];
encodedString = ..... ???? // here i need some code before i can call the following Method
[self polylineWithEncodedString:encodedString];
and here is a method i found, to get a polyline.
+ (MKPolyline *)polylineWithEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSUInteger count = length / 4;
CLLocationCoordinate2D *coords = calloc(count, sizeof(CLLocationCoordinate2D));
NSUInteger coordIdx = 0;
float latitude = 0;
float longitude = 0;
while (idx < length) {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = bytes[idx++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
float finalLat = latitude * 1E-5;
float finalLon = longitude * 1E-5;
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(finalLat, finalLon);
coords[coordIdx++] = coord;
if (coordIdx == count) {
NSUInteger newCount = count + 10;
coords = realloc(coords, newCount * sizeof(CLLocationCoordinate2D));
count = newCount;
}
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coords count:coordIdx];
free(coords);
return polyline;
}

Answer 1

Code from here works perfectly well:
https://gist.github.com/Muximize/3770235
+ (MKPolyline *)polylineWithGMEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSUInteger count = length / 4;
CLLocationCoordinate2D *coords = calloc(count, sizeof(CLLocationCoordinate2D));
NSUInteger coordIdx = 0;
float latitude = 0;
float longitude = 0;
while (idx < length) {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = bytes[idx++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
float finalLat = latitude * 1E-5;
float finalLon = longitude * 1E-5;
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(finalLat, finalLon);
coords[coordIdx++] = coord;
if (coordIdx == count) {
NSUInteger newCount = count + 10;
coords = realloc(coords, newCount * sizeof(CLLocationCoordinate2D));
count = newCount;
}
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coords count:coordIdx];
free(coords);
return polyline;
}

Answer 2

Calling...
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:#"http://maps.googleapis.com/maps/api/directions/json?origin=%#,%#&destination=%f,%f&mode=driving&sensor=false",smAppDelegate.currPosition.latitude, smAppDelegate.currPosition.longitude, ((LocationItem*)selectedAnno).coordinate.latitude, ((LocationItem*)selectedAnno).coordinate.longitude]]];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
Response...
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
[self.responseDirectionData setLength:0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[self.responseDirectionData appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
[connection release];
self.responseDirectionData =nil;
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
NSLog(#"connection established");
[connection release];
NSError *error = nil;
NSString *responseString=[[NSString alloc]initWithData:responseDirectionData encoding:NSUTF8StringEncoding];
SBJsonParser *jsonParser = [[SBJsonParser alloc] init];
NSDictionary *jsonObjects = [jsonParser objectWithString:responseString error:&error];
NSLog(#"responce = %#",jsonObjects);
NSMutableArray *ad = [jsonObjects objectForKey:#"routes"];
NSMutableArray *data2 = [[ad objectAtIndex:0] objectForKey:#"legs"];
NSMutableArray *data3 = [[data2 objectAtIndex:0] objectForKey:#"steps"];
NSLog(#"Data3 %#", data3);
NSMutableArray *polyLinesArray = [[NSMutableArray alloc] init];
for (int i = 0; i < [data3 count]; i++)
{
NSString* encodedPoints = [[[data3 objectAtIndex:i] objectForKey:#"polyline"] valueForKey:#"points"];
MKPolyline *route = [self polylineWithEncodedString:encodedPoints];
[polyLinesArray addObject:route];
}
[self.mapView addOverlays:polyLinesArray];
[polyLinesArray release];
}