iPhone Programming : Other Native Platforms - MonoTouch

The MonoTouch platform from Novell allows you to build C#- and .NET-based applications on the iPhone and iPod touch. It comes in two editions: Professional and Enterprise.

A license for the Professional Edition, intended for individual use, costs $399 per year. The Enterprise Edition, intended for corporate use, costs $999 per year (although you can buy a five-developer pack for $3,999 per year). Alternatively, you can download an evaluation version that enables development and testing against iPhone Simulator only.

1. Download and Installation

Before downloading and installing MonoTouch, you must download the latest release of Mono, the open source development platform based on the .NET Framework that allows developers to build cross-platform applications in C#. You can obtain it from http://www.mono-project.com/.

The Mono framework downloads as a disk image file containing a package installer file. Double-click on this package file to start the Mono installer, as shown in Figure 1.

After installing the Mono framework, you need to install the MonoDevelop environment before you can install MonoTouch itself. MonoDevelop is an IDE primarily designed for C# and other .NET languages and you can download it from http://monodevelop.com/; it comes as a disk image, and installation is simply a matter of dragging and dropping the MonoDevelop.app application from the disk image to your Applications folder.

Warning:

You need to use the latest MonoTouch version of MonoDevelop for Mac OS X, as it contains several fixes that are not in the mainstream version of the application. This version is linked from the MonoTouch website.

After installing Mono and MonoDevelop, you can download the trial version of the MonoTouch SDK from http://monotouch.net/DownloadTrial. MonoTouch is distributed as a package file that will automatically start the Installer when it downloads, as shown in Figure 2.

2. Building a MonoTouch Project

Double-click on the MonoDevelop application that you installed in your Applications folder, and you will be presented with something similar to Figure 3. Select File→New Solution from the MonoDevelop menu to open the New Solution window (Figure 4). From there, choose a new C#→iPhone→iPhone MonoTouch Project.

After entering the solution name, click the Forward button and then the Okay button to complete the setup process. You do not need to choose any of the optional project features (e.g., Packaging or Unix Integration). In the Solution pane, click the disclosure triangle next to the solution name to expand it, and then expand each subfolder in the same way, and you’ll be presented with something that looks a lot like Figure 5.

The default template generated by the MonoTouch SDK produces a Main.cs file that is used to start your application event loop:

using System;
using System.Collections.Generic;
using System.Linq;
using MonoTouch.Foundation;
using MonoTouch.UIKit;

namespace HelloWorld
{
    public class Application
    {
        static void Main (string[] args)
        {
            UIApplication.Main (args);
        }
    }

    // The name AppDelegate is referenced in the MainWindow.xib file.
    public partial class AppDelegate : UIApplicationDelegate
    {
        // This method is invoked when the application has loaded its UI
        // and its ready to run public override bool FinishedLaunching
        // (UIApplication app, NSDictionary options)
        {
            // If you have defined a view, add it here:
            // window.AddSubview (navigationController.View);

            window.MakeKeyAndVisible ();

            return true;
        }

        // This method is required in iPhoneOS 3.0
        public override void OnActivated (UIApplication application)
        {
        }
    }
}

					  

The default template also creates a MainWindow.xib.designer.cs file that MonoTouch will update each time you edit the MainWindow.xib file inside Interface Builder. This file will mirror all of the views, controllers, outlets, and actions that you add to your UI and then map those elements to C# properties that you can access from your own code. Here’s the default MainWindow.xib.designer.cs:

namespace HelloWorld
{
    // Base type probably should be MonoTouch.Foundation.NSObject or subclass
    [MonoTouch.Foundation.Register("AppDelegate")]
    public partial class AppDelegate
    {

        [MonoTouch.Foundation.Connect("window")]
        private MonoTouch.UIKit.UIWindow window {
         get {
           return ((MonoTouch.UIKit.UIWindow)(this.GetNativeField ("window")));
         }
         set { this.SetNativeField ("window", value); }
        }
    }
}

					  

If you select Run→Run from the MonoDevelop menu bar at this point, the application will be built, compiled to native code, and started inside iPhone Simulator. You should see something very similar to Figure 6.

Quit from iPhone Simulator and return to the MonoDevelop environment. Double-click on the MainWindow.xib file to open the NIB file in Interface Builder. Drag a button (UIButton) and a label (UILabel) into the main view window.

Next, click on the app delegate in the MainWindow.xib file and go to the Classes segment of the multisegmented control at the top of the Library window. Click on AppDelegate in the list of objects, and then click on the Outlets segment of the multisegmented control underneath the AppDelegate object. Click on the plus sign button below the outlets list to add a new outlet. Add two new outlets, calling them “button” and “label”, respectively; see Figure 7.

In the Connections Inspector (⌘-2), connect the button and label outlets to the button and label elements as you’ve done in other projects. Figure 8 shows what the finished NIB should look like (you can use the Attributes Inspector to change the appearance of the button and label).

Save your changes and return to the MonoDevelop environment. If you look again at the MainWindow.xib.designer.cs file, you should see that it reflects the changes you made to the view inside Interface Builder. The changes that MonoDevelop made are shown in bold:

namespace HelloWorld {


    // Base type probably should be MonoTouch.Foundation.NSObject or subclass
    [MonoTouch.Foundation.Register("AppDelegate")]
    public partial class AppDelegate {

        #pragma warning disable 0169
        [MonoTouch.Foundation.Connect("window")]
        private MonoTouch.UIKit.UIWindow window {
         get {
          return ((MonoTouch.UIKit.UIWindow)(this.GetNativeField("window")));
         }
         set {
          this.SetNativeField("window", value);
         }
        }

        [MonoTouch.Foundation.Connect("button")]
					private MonoTouch.UIKit.UIButton button {
					get {
					return ((MonoTouch.UIKit.UIButton)(this.GetNativeField("button")));
					}
					set {
					this.SetNativeField("button", value);
					}
					}
					[MonoTouch.Foundation.Connect("label")]
					private MonoTouch.UIKit.UILabel label {
					get {
					return ((MonoTouch.UIKit.UILabel)(this.GetNativeField("label")));
					}
					set {
					this.SetNativeField("label", value);
					}
					}
    }
}

					  

Warning:

You should not make any changes to the MainWindow.xib.designer.cs file, as the MonoTouch framework updates it automatically each time you edit your NIB file in Interface Builder.

Double-click on the Main.cs file to open it in the MonoTouch editor and add the following code directly before the line where the window is made visible (window.MakeKeyAndVisible ();):

button.TouchDown += delegate {
     label.Text = "Pushed Button";
};

Save your modifications and select Run→Run from the MonoDevelop menu bar. Once the application has been built and been deployed into iPhone Simulator, tap the Push! button. You should see something like Figure 9.