How to invoke iPhone Maps for Directions with Current Location as Start Address

Solution 1:

Pre iOS 6

You need to use Core Location to get the current location, but with that lat/long pair, you can get Maps to route you from there, to a street address or location. Like so:

CLLocationCoordinate2D currentLocation = [self getCurrentLocation];
// this uses an address for the destination.  can use lat/long, too with %f,%f format
NSString* address = @"123 Main St., New York, NY, 10001";
NSString* url = [NSString stringWithFormat: @"http://maps.google.com/maps?saddr=%f,%f&daddr=%@",
                    currentLocation.latitude, currentLocation.longitude,
                    [address stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL: [NSURL URLWithString: url]];

Finally, if you do want to avoid using CoreLocation to explicitly find the current location, and want to use the @"http://maps.google.com/maps?saddr=Current+Location&daddr=%@" url instead, then see this link that I provided in comments below for how to localize the Current+Location string. However, you are taking advantage of another undocumented feature, and as Jason McCreary points out below, it may not work reliably in future releases.

Update for iOS 6

Originally, Maps used Google maps, but now, Apple and Google have separate maps apps.

1) If you wish to route using the Google Maps app, use the comgooglemaps URL scheme:

NSString* url = [NSString stringWithFormat: @"comgooglemaps://?daddr=%@&directionsmode=driving",
                    [address stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
BOOL opened = [[UIApplication sharedApplication] openURL: [NSURL URLWithString: url]];

2) To use Apple Maps, you can use the new MKMapItem class for iOS 6. See the Apple API docs here

Basically, you will use something like this, if routing to destination coordinates (latlong):

    MKPlacemark* place = [[MKPlacemark alloc] initWithCoordinate: latlong addressDictionary: nil];
    MKMapItem* destination = [[MKMapItem alloc] initWithPlacemark: place];
    destination.name = @"Name Here!";
    NSArray* items = [[NSArray alloc] initWithObjects: destination, nil];
    NSDictionary* options = [[NSDictionary alloc] initWithObjectsAndKeys:
                                 MKLaunchOptionsDirectionsModeDriving, 
                                 MKLaunchOptionsDirectionsModeKey, nil];
    [MKMapItem openMapsWithItems: items launchOptions: options];

In order to support both iOS 6+ and pre iOS 6 in the same code, I'd recommend using something like this code that Apple has on the MKMapItem API doc page:

Class itemClass = [MKMapItem class];
if (itemClass && [itemClass respondsToSelector:@selector(openMapsWithItems:launchOptions:)]) {
   // iOS 6 MKMapItem available
} else {
   // use pre iOS 6 technique
}

This would assume that your Xcode Base SDK is iOS 6 (or Latest iOS).

Solution 2:

NSString* addr = [NSString stringWithFormat:@"http://maps.google.com/maps?daddr=Current Location&saddr=%@",startAddr];
NSURL* url = [[NSURL alloc] initWithString:[addr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:url];
[url release];

This works but only when the iPhone/iPod language is set in English. If you want to support other languages you'll have to use a localized string to match the Maps bookmark name.

Solution 3:

This works on iPhone:

http://maps.google.com/maps?saddr=Current Location&daddr=123 Main St,Ottawa,ON

Solution 4:

You can use a preprocessor #define like:

#define SYSTEM_VERSION_LESS_THAN(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)

to understand your iOS version. Then, I can use this code to support iOS 6, too:

NSString* addr = nil;
if (SYSTEM_VERSION_LESS_THAN(@"6.0")) {
   addr = [NSString stringWithFormat:@"http://maps.google.com/maps?daddr=%1.6f,%1.6f&saddr=Posizione attuale", view.annotation.coordinate.latitude,view.annotation.coordinate.longitude];
} else {
   addr = [NSString stringWithFormat:@"http://maps.apple.com/maps?daddr=%1.6f,%1.6f&saddr=Posizione attuale", view.annotation.coordinate.latitude,view.annotation.coordinate.longitude];
}

NSURL* url = [[NSURL alloc] initWithString:[addr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:url];