从谷歌API解码路由

Question

我拼命地想找到一种方法，如何从谷歌API获取所有坐标（或折线）的数组，以便我可以在MKMapView上绘制我的路线。（顺便说一下，我不想使用RegexKitLite）

正如我在其他地方发现的那样，这应该是调用 API 的正确方法。

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];

这是我找到的一种方法，可以得到一条折线。

+ (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

这里的

代码运行良好：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];

响应。。。

-(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];
}