Initiate a call with MonoTouch

Initiating calls, text messages and triggering other applications on the iPhone is a pretty basic requirement for MonoTouch applications - but it still took me a little while to "translate" the examples I found (eg developertips).






The mechanism is pretty simple - you just need to construct a Url with a specific 'scheme' and call the OpenURL method. I kept finding examples using self to reference OpenURL so it took me a second to figure out the method is actually on UIApplication. I'm working with iPhone OS 3.0 so OpenURL returns a bool if the action is 'possible': false if that scheme is not recognised on the device.

public partial class AppDelegate : UIApplicationDelegate
{
    public override bool FinishedLaunching(UIApplication app, NSDictionary options)
    {
        window.MakeKeyAndVisible();
        buttonCall.TouchDown += delegate { // trigger action
            NSUrl url = new NSUrl("tel:" + textfieldInput.Text);
            if (!UIApplication.SharedApplication.OpenUrl(url))
            {
                var av = new UIAlertView("Not supported"
                    , "Scheme 'tel:' is not supported on this device"
                    , null
                    , "Ok thanks"
                    , null);
                av.Show();
            }
        };

* Note: you can read about the singleton SharedApplication property in the UIApplication reference.

Some of the other common schemes look like this:

new NSUrl("sms:" + textfieldInput.Text);
new NSUrl("http://maps.google.com/maps?q=" + textfieldInput.Text); // opens Maps
new NSUrl("http://" + textfieldInput.Text); // opens Safari
new NSUrl("mailto:you@gmail.com?subject=" + textfieldInput.Text);

and two others I've added for testing are

new NSUrl("tweetie:///post?message=" + textfieldInput.Text);
new NSUrl("comgoogleearth://");

You can view the full code for the test app - Main.cs and MainWindow.xib.designer.cs - the Xib is basically a textfield and seven buttons - complete source in MonoTouch solution ZIP (14k).

Here's a link to Apple's Url Scheme Reference (PDF)
and two lists of the currently available url types: iPhone Url Schemes & AppLookup