Core Controls in Mac OS X: Part 1/2

Core Controls in OS X Applications

Core Controls in OS X Applications

If you’re an iOS developer and you’re interested in learning about Mac development, you’re in luck – with your iOS skills, you’ll find it quite easy to learn!

Many of the Cocoa Touch APIs and design patterns you know and love like NSString, NSMutableArray, and delegates have direct equivalents in Mac development. You’ll feel right at home!

However, one big difference with Mac development are there are different controls. Gone are UIButtons and UITextFields – instead there are similar (but slightly different) Mac variants.

This tutorial will introduce you to some of the more common user interface controls of OS X — the foundation upon which most Mac apps are built. You’ll learn about these controls, as well as the methods and properties you’ll need to understand in order to get up and running as a developer! :]

In this tutorial, you’ll be creating a simple Mac application like the popular game Mad Libs. Mad Libs is a word game where you can insert different words in a block of text in order to create a story — which often has hilarious results!

Once you’ve completed both parts of this tutorial, you’ll have a fundamental understanding of the following controls:

• Labels and Text Fields
• Combo Boxes
• Popup Buttons
• Text Views
• Sliders
• Date Pickers
• Buttons
• Radio Buttons
• Check Buttons
• Image Views

Before you go through this tutorial, you should go through our How to Make a Simple Mac App Tutorial to learn the basics of Mac development.

The best way to learn any new programming platform is to dive right in and get started — so without further ado, here’s your introduction to Core Controls in Mac OS X! :]

Getting Started

Launch Xcode, and choose File\New\Project. When the Choose a template dialog appears, select OS X\Application\Cocoa Application, which is the template you use to create an app with a GUI on the Mac. Then click Next.

In the project options dialog, enter MadLibs as the product name. Also enter a unique company identifier and make sure Use Automatic Reference Counting is checked, as below:

Note: Automatic Reference Counting works on the Mac the same way it does on iOS. If you’re new to ARC or want to learn more about how it works, check out our tutorial on the matter!

Click Next. Finally, choose a location where you’d like to save your new project, and click Create.

Once Xcode has finished generating the project files, you’ll be presented with the main Xcode window. Go ahead and click Run in the toolbar. If all goes well, you should see the following:

You’ve built a working application — without any coding at all. The window is empty right now, but you’re going to fill it up with some controls and make it look amazing! :]

Click on MainMenu.xib in the project explorer, and you’ll see a window which already contains a view, referred to as the window’s content view. You’re going to create a view controller that will be the owner of this view.

From the File menu choose New\File, or alternately you can use the keyboard shortcut Command + N. When the Choose a template dialog appears, select OS X\Cocoa\Objective-C class, as shown below:

Click Next to move on to the the file options dialog. Enter RootViewController as the Class and make it a subclass of NSViewController. Make sure With XIB for user interface is NOT checked, then click Next.

Finally, click Create to save the new view controller.

Note: the reason that you did not check With XIB for user interface is because this view controller is going to be responsible for the Main Window’s view, which is already made for you in MainWindow.xib.

Now you need to create an instance of your new view controller and associate the Main Window’s view with the view controller. Here, you have two choices — you can do it directly in code, or you can do it the quick and easy way: by using the Interface Builder! :]

Note: If you would like to learn how to create an instance of a view controller in code, please have a look at the How to Make a Simple Mac App tutorial.

Select MainMenu.xib in the project explorer to open it in Interface Builder. In the lower right-hand corner of the window, you’ll find the the Object Library palette. In the Object Library palette, find View Controller and drag it to the Objects palette on the left-hand side of the window, like so:

By default, this view controller object is an instance of NSViewController, but you’ll need this to be an instance of your RootViewController class instead — you will change that right now.

To do this, click on the newly created view controller object, go to the utilities palette and then select the identity inspector tab. Rename the class to RootViewController, as in the screenshot below:

In order to make your newly created view controller the owner of the window’s content view, you’ll need to connect its view outlet to the main window’s content view.

To do that, select the main window in the Objects palette to display it on the screen, and then select your view controller object. Then, go back to the utilities palette and select the connections inspector tab. From the Outlets section, click and drag the view outlet to the main window. This sequence of events is illustrated in the screenshot below:

And that’s it! You’ve now configured your app to instantiate an instance of your RootViewController class, and you’ve made it the owner of the main window’s content view. And you still haven’t written a single line of code! :]

If you’ve followed the above instructions, then everything should be hooked up properly. But before you go any further, take a minute to ensure that everything’s working by following the steps below! :]

You’re going to override awakeFromNib in your RootViewController class, since this method is part of an object’s life cycle when it’s instantiated from a XIB file. If everything has been connected correctly, then this method will be called when the application runs, and the view controller should have a view associated with it.

Open RootViewController.m and add the following:

-(void)awakeFromNib
{
    NSLog(@"View controller instance with view: %@", self.view);
}

This will simply output some debug code to the console to indicate that (a) this code is called, and (b) that the associated view is valid.

Buld and run your app. In the Output pane of the Debug area, you should a message similar to the following:

MadLibs[29008:303] View controller instance with view: <NSView: 0x101a0ef40>

If you see the line above, then you’ve verified that both the view and the view controller have been instantiated, and the two are connected properly!

Now that the basic framework has been laid down, you can now move on to the main focus of this tutorial — adding controls to your app! :]

Each of the remaining steps in this tutorial will focus on a single, different control. You’ll learn the basics of each control, and then implement each one in the Mad Libs app to try it out.

Note: In this tutorial, you’re using Auto Layout, a new feature introduced in OS X 10.7 and iOS 6. If you’re not familiar with this feature, you can learn more by reading Beginning Auto Layout in iOS 6 by Matthijs Hollemans. It’s focused on iOS, but Auto Layout works exactly the same in OS X!