TweetFollow Us on Twitter

Creating a Cocoa AppController Class

Volume Number: 21 (2005)
Issue Number: 1
Column Tag: Programming

Getting Started

by Dave Mark

Creating a Cocoa AppController Class

In our last Cocoa column, we downloaded the latest and greatest version of Xcode. We created a Foundation Tool, which is an Objective-C program with a console-based interface.

This month, we're going to build a Cocoa app with an interface we designed using Interface Builder. The app will use Cocoa's NSSpeechSynthesizer class to speak a line of text. We'll add a pushbutton to start the speech and another to halt it, even in mid-sentence. The example comes from Chapter 4 of Aaron Hillegass' book, Cocoa Programming for Mac OS X. We'll start by taking a look at a class diagramming approach Aaron uses throughout the book.

A Diagram Speaks a Thousand Words

Before we actually start the process of building our project, take a look at the object diagram shown in Figure 1. This diagramming convention was developed by Aaron Hillegas and I find it works quite well at describing the interrelationships between the classes, objects, methods, and instance variables that come together to make your program work.

The class at the heart of this example is the AppController class. Note that this class features two methods: sayIt: and stopIt:. In Hillegas' drawings, each box represents a class and each arrow connecting two boxes represents the control-dragging connection you create in Interface Builder. For example, in Figure 1, note that 4 of the 5 classes are Cocoa classes (they start with NS). All of our code will be built into a new class that we create called AppController. We'll create two instances of NSButton, one labeled Say it and one labeled Stop. Each of the buttons will target one of the two AppController methods. When we build the project in Interface Builder, we'll create an instance of AppController, then control-drag from each button to the AppController instance and double-click on the method we want called to finish the connection.

We'll also add instance variables to AppController to keep track of the NSTextField (so we can retrieve the text to say it) and the NSSpeechSynthesizer (so we can send it the text to start speaking and send it a stop message to halt the speaking).


Figure 1. An object diagram for the first incarnation of our SpeakLine program.

Create the SpeakLine Project

Launch Xcode and create a new project using the Cocoa Application template. Name the project SpeakLine.

Editing the .nib File

In your SpeakLine project file, in the Groups & Files pane, find the file MainMenu.nib and double-click it to launch Interface Builder. You can find the file in the NIB Files group as well as under the SpeakLine group, in the Resources subgroup.

Once Interface Builder launches, click on the third icon from the left in the palette window, then drag an NSTextField from the palette onto the main window. As you can see in Figure 2, the NSTextField is in the upper-left corner of the set of text items.


Figure 2. Dragging out an NSTextField.

Drag the NSTextField so it is almost as wide as the window (so the dashed blue line appears when you get about a scrollbar's width from the right side of the window). Double-click on the text field and change its text to read Peter Piper picked a peck of pickled peppers or, if you are by yourself, perhaps something a bit more spicy.

Next, click on the second icon from the left at the top of the palette window to show the control palette items. Drag two buttons onto the window, below the NSTextField, with the proper spacing between them and the right side of the window. Label the right button Say It and the left button Stop (double-click on a button to edit its label).

Finally, resize the window itself, making it as short as possible. Figure 3 shows my Interface Builder session. In this picture, I am dragging the Stop button into place. You can see the dashed blue lines showing that the two buttons are aligned with each other and that the Stop button is the correct distance from the text field above it and the Say It button to its right.


Figure 3. Use the blue dashed lines to line up your buttons and NSTextField.

Create the AppController Class

Now that your interface is laid out, it's time to create the new AppController class.

Click on the MainMenu.nib window and click on the Classes tab. Scroll all the way to the left and click on the NSObject class. With NSObject highlighted, select Subclass NSObject from the Classes menu. Name the new subclass AppController (see Figure 4).


Figure 4. Click on the NSObject class and select Subclass NSObject from the Classes menu.

Now you'll add two actions (one for each button) and an outlet (an instance variable that points to the text field) to AppController. Open the Info window by selecting Show Info from the Tools menu. Click on the AppController class in the classes tab in the MainMenu.nib window, then click on the Info window and select Attributes from the popup near the top of the Info window.

Click on the Actions tab, then click on the Add button at the bottom right of the Info window. When the new action appears, name it sayIt:, then click Add and name the second action stopIt: (see Figure 5).


Figure 5. The Info window, showing the AppController class attributes.

Next, click on the Outlet tab and click Add to add an outlet named textField to AppController. Click in the Type column and select NSTextField to set the textField type to NSTextField instead of the generic id.

If you look back at Figure 1, you'll see that we've addressed 3 of the 4 arrows in the object diagram. We'll add the missing outlet, speechSynth, in code in just a minute.

Be sure that the AppController class is selected in the Classes tab and select Create Files for AppController from the Classes menu. This will generate two source files (AppController.m and AppController.h) in your Xcode project which we'll edit in a bit.

Next, create an instance of the AppController class by selecting Instantiate AppController from the Classes menu. Interface Builder will switch the MainMenu.nib window to the Instances tab and a new, blue cube will appear with the name AppController.

As you can see in Figure 6, the AppController instance is represented by a blue cube. The tiny exclamation point in a circle to the lower right of the blue cube tells you that there is at least one unconnected outlet. Let's take care of that now.


Figure 6. The new instance of AppController with an unconnected outlet.

Making Connections

Before you start making your connections, take a quick peek back at Figure 1. There are four connections that need to be made. Three of them will be made by control-dragging. The fourth (speechSynth) will be made in code.

First, we'll connect AppController's textField outlet so it points to the NSTextField in the main window. Make sure the Info window is open before you start your drag.

Control-drag from the AppController blue cube to the text field in the main window. When you release the mouse button, the Info window should display its Connections pane and list the textField outlet. Either double-click on the textField line or make sure it is selected and click the Connect button in the lower-right corner of the Info window (Figure 7).


Figure 7. Click the Connect button to connect the AppController to the textField.

Next, we'll connect the two buttons to their respective AppController methods. Control-drag from the Say It button to the AppController cube then, in the Info window, connect to the sayIt: method.

Now control-drag from the Stop button to the AppController cube and connect to the stopIt: method.

NSWindow's initialFirstResponder

The last bit of Interface Builder work we'll do is to set the NSWindow initialFirstResponder outlet to point to the text field. This tells the window that you want the text field to be active when the window appears so you don't have to click in the text field to start typing. To get a feel for this, try running the program with the initialFirstResponder connected and then with it disconnected to see what happens.

Control-drag from the Window icon (to the left of the blue AppController cube) to the text field. In the Info window, click on the initialFirstResponder outlet and click the Connect button.

Now let's type in the code!

Enter the AppController Code

Head back over to Xcode and edit the AppController.h file. We'll add the declaration of speechSynth:


#import <Cocoa/Cocoa.h>


@interface AppController : NSObject 
{
	IBOutlet NSTextField *textField;
	NSSpeechSynthesizer *speechSynth;
} 

- (IBAction)sayIt:(id)sender;
- (IBAction)stopIt:(id)sender; 
@end

Next, edit AppController.m to look like this:

#import "AppController.h"
@implementation AppController

- (id)init 
{  
	[super init];
 	NSLog( @"init" );
 	speechSynth = [[NSSpeechSynthesizer alloc] initWithVoice:nil];
	return self; 
 }


- (IBAction)sayIt:(id)sender 
{  
	NSString *string = [textField stringValue];
 if ( [string length] == 0) {   
 	return;  
 }

 [speechSynth startSpeakingString:  string];

 	NSLog( @"Have started to say: %@", string ); 
 }

- (IBAction)stopIt:(id)sender 
{
	NSLog( @"stopping" );
	[speechSynth stopSpeaking]; 
}

- (void)dealloc 
{
	NSLog( @"dealloc" );
	[speechSynth release];
	[super dealloc];
}
@end 

Build and run the application. Notice that you can click the Stop button to stop the speaking, even in the middle.

Take a look through the code. Most of it should make sense, especially if you've been following along with my previous Cocoa columns.

The init: method calls the superclasses' init drops a message to the console, creates an instance of the NSSpeechSynthesizer, then returns a pointer to itself.

sayIt: sends a stringValue message to textField to retrieve the text, then, if there's at least one character in the field, send it via a startSpeakingString message to speechSynth. The string is sent to the console as well, just to help you follow along.

stopIt: sends a message to the console, then sends a stopSpeaking message to speechSynth.

dealloc: is called when the AppController object is released. You'll likely never see the console message, since the AppController object was created automatically and is never sent a release message. When it is loaded from the .nib file, the AppController instance has a ref count of one. Not a big deal, but worth noting.

Till Next Month...

One thing that Aaron does in his book is add a color well to the program so the user can choose their own text color. See if you can do this on your own. You'll want to take advantage of the NSColorWell class.

Be sure to check out http://www.spiderworks.com and I'll see you next month...


Dave Mark is a long-time Mac developer and author and has written a number of books on Macintosh development, including Learn C on the Macintosh, Learn C++ on the Macintosh, and The Macintosh Programming Primer series. Dave's been busy lately cooking up his next concoction. Want a peek? http://www.spiderworks.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Lyn 1.5.11 - Lightweight image browser a...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
NeoOffice 2014.11 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LaunchBar 6.4 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
VOX 2.5.1 - Music player that supports m...
VOX is a beautiful music player that supports many filetypes. The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all... Read more
NetNewsWire 4.0.0 - RSS and Atom news re...
NetNewsWire is the best way to keep up with the sites and authors you read most regularly. Let NetNewsWire pull down the latest articles, and read them in a distraction-free and Mac-like way. Native... Read more
MacUpdate Desktop 6.0.6 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
ForkLift 2.6.5 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Drive Genius 4.1.0 - Powerful system uti...
Drive Genius 4 gives you faster performance from your Mac while also protecting it. The award-winning and improved DrivePulse feature alerts you to hard drive issues before they become major problems... Read more

Biz Builder Delux (Games)
Biz Builder Delux 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Ah, there's nothing like the rhythmic bustle of a burgeoning business burg... especially when you're the one building it... | Read more »
Auroch Digital is Bringing Back Games Wo...
| Read more »
Carbo - Handwriting in the Digital Age...
Carbo - Handwriting in the Digital Age 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Draggy Dead (Games)
Draggy Dead 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Ditch your dead end job and take up a rewarding career in Grave Robbing today!Guide the recently deceased to a fun filled life of... | Read more »
Bad Dinos (Games)
Bad Dinos 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Apple Watch isn't Great as a Fi...
| Read more »
Show the World What You See With Stre.am...
Live broadcasting is getting popular on mobile devices, which is why you can now get Stre.am, by Infinite Takes. [Read more] | Read more »
PhotoTime's 2.1 Update Adds Apple W...
The latest PhotoTime update is adding even more functionality to the handy photo organizing app. Yep, including Apple Watch support. [Read more] | Read more »
Oh My Glob! Adventure Time Puzzle Quest...
Finn and Jake are taking over D3 Go!'s popular puzzle game series in the upcoming Adventure Time Puzzle Quest. [Read more] | Read more »
Earthcore: Shattered Elements - Tips, Tr...
At first glance, Earthcore: Shattered Elements seems like a rather simple card-battling game. Once you’re introduced to skills that will change quite a bit. Even more so once you start to acquire hero cards. But it’s not so complicated that we... | Read more »

Price Scanner via MacPrices.net

OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more
Price drop on 2014 15-inch Retina MacBook Pro...
B&H Photo has dropped prices on 2014 15″ Retina MacBook Pros by $200. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 save $200 - 15″ 2.5GHz... Read more
With a Mission to Make Mobile Free, Scratch W...
Scratch Wireless, claiming to be the world’s first truly free mobile service, has announced the availability of a new Scratch-enabled Android smartphone, the Coolpad Arise. The smartphone is equipped... Read more
First-Ever Titanium Alloy Curved iPhone 6 Scr...
One of the most common problems with mobile phones is damage to the screens. The slightest drop can cause a dreaded spider web of gashes and cracks in the glass panel surface that can cost $hundreds... Read more
Preorder new 12-inch MacBook, $10 off, save o...
Adorama has new 12″ Retina MacBooks available for preorder for $10 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB... Read more
Will iOS 9 Finally Bring Productivity Friendl...
Ah, the irony. From its original announcement in 2010, Apple has doggedly insisted that the iPad remain “simple,” thus arbitrarily limiting its considerable potential as a content creation and... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
Business Development Manager - *Apple* Pay...
**Job Summary** Apple Pay is seeking an experienced Business Development professional to join the Apple Pay team to develop partnerships and strategic alliances with Read more
Project Manager, *Apple* Retail New Store O...
**Job Summary** An Apple Retail New Store Openings & Remodels Project Manager is responsible for successfully managing the openings, remodels, and small works of Read more
SW QA Engineer - *Apple* TV - Apple (United...
**Job Summary** The Apple TV team is looking for experienced Quality Assurance Engineers with a passion for delivering first in class home entertainment solutions. **Key Read more
Partner Marketing Manager - *Apple* Pay - A...
**Job Summary** The Apple Pay partner marketing team is looking for a marketing manager to develop and drive US marketing programs with our financial institution Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.