I wrote simple application which draws route between two locations on MapKit. I am using Google Map API. I used resources I found online and here's the code I am using to make request to Google:
_httpClient = [AFHTTPClient clientWithBaseURL:[NSURL URLWithString:@"http://maps.googleapis.com/"]];
[_httpClient registerHTTPOperationClass: [AFJSONRequestOperation class]];
[_httpClient setDefaultHeader:@"Accept" value:@"application/json"];
NSMutableDictionary *parameters = [[NSMutableDictionary alloc] init];
[parameters setObject:[NSString stringWithFormat:@"%f,%f", coordinate.latitude, coordinate.longitude] forKey:@"origin"];
[parameters setObject:[NSString stringWithFormat:@"%f,%f", endCoordinate.latitude, endCoordinate.longitude] forKey:@"destination"];
[parameters setObject:@"true" forKey:@"sensor"];
NSMutableURLRequest *request = [_httpClient requestWithMethod:@"GET" path: @"maps/api/directions/json" parameters:parameters];
request.cachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc]initWithRequest:request];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject){
NSInteger statusCode = operation.response.statusCode;
if (statusCode == 200)
{
NSLog(@"Success: %@", operation.responseString);
}
else
{
NSLog(@"Status code = %d", statusCode);
}
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Error: %@", operation.responseString);
}
];
[_httpClient enqueueHTTPRequestOperation:operation];
This works flawlessly. When I run this and try to show route between LA and Chicago, here's how it looks like:
BUT. When I zoom map to street level, here's how route looks like:
Does anyone know how can I achieve that route I am drawing follows streets when map is zoomed? I'd like route to show exact path through the streets. I don't know if some additional parameter needs to be added to my request to Google.
Any help or advice would be great. Many thanks in advance!
[edit #1: Adding request URL and response from Google]
My request URL after creating operation object from code above looks like this:
http://maps.googleapis.com/maps/api/directions/json?sensor=true&destination=34%2E052360,-118%2E243560&origin=41%2E903630,-87%2E629790
Just paste that URL to your browser and you will see the JSON data Google sends as the response which I get in my code also.
[edit #2: Parsing answer from Google and building the path]
- (void)parseResponse:(NSData *)response
{
NSDictionary *dictResponse = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableContainers error:nil];
NSArray *routes = [dictResponse objectForKey:@"routes"];
NSDictionary *route = [routes lastObject];
if (route)
{
NSString *overviewPolyline = [[route objectForKey: @"overview_polyline"] objectForKey:@"points"];
_path = [self decodePolyLine:overviewPolyline];
}
}
- (NSMutableArray *)decodePolyLine:(NSString *)encodedStr
{
NSMutableString *encoded = [[NSMutableString alloc] initWithCapacity:[encodedStr length]];
[encoded appendString:encodedStr];
[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];
CLLocation *location = [[CLLocation alloc] initWithLatitude:[latitude floatValue] longitude:[longitude floatValue]];
[array addObject:location];
}
return array;
}
