Drawing route partially not getting required output in iPhone MapView - iphone

Question

I am trying to draw route between two points using polyline . I got somewhat route but not correct and I think it will get confused at the turn . I am using google api for getting points of route .Following is code what i tried please check .
- (IBAction)onclickDrawButton:(id)sender
{
flag=TRUE;
NSString *startpoint=[satrtTextfield text];
NSString *endpoint=[endTextfield text];
NSMutableString *urlString=[NSMutableString stringWithFormat:#"http://maps.googleapis.com/maps/api/directions/json?origin=%#&destination=%#&sensor=false",startpoint,endpoint];
NSURL *url = [NSURL URLWithString:urlString];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
delegate:self];
if(connection)
{
NSLog(#"connectin done");
}
}
-(void)connection:(NSURLConnection*)connection didReceiveResponse: (NSURLResponse*)response
{
if(flag)
{
recievedRoutes=[[NSMutableData alloc]init];
}
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
if(flag){
NSString *jsonResult = [[NSString alloc] initWithData:recievedRoutes encoding:NSUTF8StringEncoding];
NSLog(#"json response %#",jsonResult);
NSDictionary *partialJsonDict=[jsonResult JSONValue];
NSArray *items=[partialJsonDict valueForKey:#"routes"];
//NSLog(#"responsed valued %#",[[items objectAtIndex:0]valueForKey:#"legs"]);
NSArray *aary=[[items objectAtIndex:0]valueForKey:#"legs"];
NSLog(#"legs array wuth polyline %#",[[aary objectAtIndex:0]valueForKey:#"steps"]);
NSArray *steps=[[aary objectAtIndex:0]valueForKey:#"steps"];
NSLog(#"steps %#",[[steps objectAtIndex:1]objectForKey:#"polyline"]);
NSMutableString *string=[[NSMutableString alloc]init];
for(int i=0;i<[steps count];i++)
{
//NSLog(#"steps i value %#",[[[steps objectAtIndex:i]objectForKey:#"polyline"]objectForKey:#"sttpoints"]);
[string appendString:[[[steps objectAtIndex:i]objectForKey:#"polyline"]objectForKey:#"points"]];
}
NSLog(#"final %#",string);
MKPolyline *polyline=[self polylineWithEncodedString:string];
[mapView addOverlay:polyline];
[self zoomToFitMapAnnotations:mapView];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
if(flag){
[recievedRoutes appendData:data];
}
}
//to decode polyline and retrives coordintes i have used following method
-(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;
NSLog(#"in encoding %f %f ",latitude,longitude);
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;
}
// to draw actual route
- (MKOverlayView *)mapView:(MKMapView *)mapView
viewForOverlay:(id<MKOverlay>)overlay {
MKPolylineView *overlayView = [[MKPolylineView alloc] initWithOverlay:overlay];
overlayView.lineWidth = 2;
overlayView.strokeColor = [UIColor purpleColor];
overlayView.fillColor = [[UIColor purpleColor] colorWithAlphaComponent:0.1f];
return overlayView;
}

Answer 1

After your line
NSArray *steps=[[aary objectAtIndex:0]valueForKey:#"steps"];
replace lines with this may work
NSMutableArray *polyLinesArray = [[NSMutableArray alloc] init];
for (int i = 0; i < [steps count]; i++)
{
NSString* encodedPoints = [[[steps objectAtIndex:i] objectForKey:#"polyline"] valueForKey:#"points"];
MKPolyline *route = [self polylineWithEncodedString:encodedPoints];
[polyLinesArray addObject:route];
}
[self.mapView addOverlays:polyLinesArray];
[polyLinesArray release];