Opens apple maps app from ios app with directions

You can open maps with direction using this code : (assuming your id< MKAnnotation > class has a CLLocationCoordinate2D public property named "coordinate")

MKPlacemark *placemark = [[MKPlacemark alloc] initWithCoordinate:[annotation coordinate] addressDictionary:nil];
MKMapItem *mapItem = [[MKMapItem alloc] initWithPlacemark:placemark];
[mapItem setName:"WhereIWantToGo"]];
NSDictionary *options = @{MKLaunchOptionsDirectionsModeKey : MKLaunchOptionsDirectionsModeDriving};
[mapItem openInMapsWithLaunchOptions:options];

You can also change the button, actually you are using a standard style button :

[UIButton buttonWithType:UIButtonTypeDetailDisclosure];

But you can alloc your custom button with an image or a label :

[[UIButton alloc] initWithImage:[UIImage imageNamed:"directionIcon.png"]];

Here is code to open Map app with directions:

Objective-C Code

NSString* directionsURL = [NSString stringWithFormat:@"http://maps.apple.com/?saddr=%f,%f&daddr=%f,%f",self.mapView.userLocation.coordinate.latitude, self.mapView.userLocation.coordinate.longitude, mapPoint.coordinate.latitude, mapPoint.coordinate.longitude];
if ([[UIApplication sharedApplication] respondsToSelector:@selector(openURL:options:completionHandler:)]) {
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString: directionsURL] options:@{} completionHandler:^(BOOL success) {}];
} else {
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString: directionsURL]];
}

with the mapPoint is where you want to direction to.

Swift3 or later

let directionsURL = "http://maps.apple.com/?saddr=35.6813023,139.7640529&daddr=35.4657901,139.6201192"
guard let url = URL(string: directionsURL) else {
    return
}
if #available(iOS 10.0, *) {
    UIApplication.shared.open(url, options: [:], completionHandler: nil)
} else {
    UIApplication.shared.openURL(url)
}

Note that saddr, daddr is urlencoded string of location name or location coordinate (about encode URL look at here).

directionsURL example:

// directions with location coordinate
"http://maps.apple.com/?saddr=35.6813023,139.7640529&daddr=35.4657901,139.6201192"
// or directions with location name
"http://maps.apple.com/?saddr=Tokyo&daddr=Yokohama"
// or directions from current location to destination location
"http://maps.apple.com/?saddr=Current%20Location&daddr=Yokohama"

More options parameters (like transport type, map type ...) look at here