How can I launch the Google Maps iPhone application from within my own native application?

For iOS 5.1.1 and lower, use the openURL method of UIApplication. It will perform the normal iPhone magical URL reinterpretation. so

[someUIApplication openURL:[NSURL URLWithString:@"http://maps.google.com/maps?q=London"]]

should invoke the Google maps app.

From iOS 6, you'll be invoking Apple's own Maps app. For this, configure an MKMapItem object with the location you want to display, and then send it the openInMapsWithLaunchOptions message. To start at the current location, try:

[[MKMapItem mapItemForCurrentLocation] openInMapsWithLaunchOptions:nil];

You'll need to be linked against MapKit for this (and it will prompt for location access, I believe).

Exactly. The code that you need to achieve this is something like that:

UIApplication *app = [UIApplication sharedApplication];
[app openURL:[NSURL URLWithString: @"http://maps.google.com/maps?q=London"]];

since as per the documentation, UIApplication is only available in the Application Delegate unless you call sharedApplication.

To open Google Maps at specific co-ordinates, try this code:

NSString *latlong = @"-56.568545,1.256281";
NSString *url = [NSString stringWithFormat: @"http://maps.google.com/maps?ll=%@",
[latlong stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:url]];

You can replace the latlong string with the current location from CoreLocation.

You can also specify the zoom level, using the (”z“) flag. Values are 1-19. Here's an example:

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://maps.google.com/maps?z=8"]];

For the phone question, are you testing on the simulator? This only works on the device itself.

Also, openURL returns a bool, which you can use to check if the device you're running on supports the functionality. For example, you can't make calls on an iPod Touch :-)

If you need more flexibility than the Google URL format gives you or you would like to embed a map in your application instead of launching the map app here is an example.

It will even supply you with the source code to do all of the embedding.

If you need more flexabilty than the Google URL format gives you or you would like to embed a map in your application instead of launching the map app there is an example found at https://sourceforge.net/projects/quickconnect.

Working Code as on Swift 4:

Step 1 - Add Following to info.plist

<key>LSApplicationQueriesSchemes</key>
<array>
<string>googlechromes</string>
<string>comgooglemaps</string>
</array>

Step 2 - Use Following Code to Show Google Maps

    let destinationLatitude = "40.7128"
    let destinationLongitude = "74.0060"

    if UIApplication.shared.canOpenURL(URL(string: "comgooglemaps:")!) {
        if let url = URL(string: "comgooglemaps://?ll=\(destinationLatitude),\(destinationLongitude)"), !url.absoluteString.isEmpty {
            UIApplication.shared.open(url, options: [:], completionHandler: nil)
        }
    }else{
        if let url = URL(string: "http://maps.google.com/maps?ll=\(destinationLatitude),\(destinationLongitude)"), !url.absoluteString.isEmpty {
            UIApplication.shared.open(url, options: [:], completionHandler: nil)
        }
    }