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

Macs Fan Control 1.4.7.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
Boom 2 1.5.2 - $14.99
Boom 2 is a system-wide volume booster and equalizer app that is designed especially for OS X 10.10 Yosemite. It comes with a smart interface, self-calibrates itself according to your Mac, offers... Read more
MacFamilyTree 8.1.3 - Create and explore...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more
WhiteCap 6.6 - Visual plug-in for iTunes...
WhiteCap is a sleek and sophisticated music visualizer and screensaver that features futuristic, wireframe mesh visuals with dynamic backgrounds and colors. WhiteCap contains thousands of visual... Read more
VOX 2.8.14 - Music player that supports...
VOX just sounds better! 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 audio formats you should ever need.... Read more
Paparazzi! 1.0b2 - Make user-defined siz...
Paparazzi! is a small utility for OS X that makes screenshots of webpages. This very simple tool takes screenshots of websites which do not fit on one screen. You specify the desired width, minimal... Read more
Carbon Copy Cloner 4.1.13 - Easy-to-use...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
TrailRunner 3.8.832 - Route planning for...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more
VueScan 9.5.65 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Adobe Illustrator CC 2017 21.0.2 - Profe...
Illustrator CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Illustrator customer). Adobe Illustrator CC 2017 is the industry... Read more

Stickman Surfer rides in with the tide t...
Stickson is back and this time he's taken up yet another extreme sport - surfing. Stickman Surfer is out this Thursday on both iOS and Android, so if you've been following the other Stickman adventures, you might be interested in picking this one... | Read more »
Z-Exemplar (Games)
Z-Exemplar 1.4 Device: iOS Universal Category: Games Price: $3.99, Version: 1.4 (iTunes) Description: | Read more »
5 dastardly difficult roguelikes like th...
Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »
Last week on PocketGamer
Welcome to a weekly feature looking back on the past seven days of coverage on our sister website, PocketGamer. It’s taken a while for 2017 to really get going, at least when it comes to the world of portable gaming. Thank goodness, then, for... | Read more »
ROME: Total War - Barbarian Invasion set...
To the delight of mobile strategy fans, Feral Interactive released ROME: Total War just a few months ago. Now the game's expansion, Barbarian Invasion is marching onto iPads as a standalone release. [Read more] | Read more »
Yuri (Games)
Yuri 1.0 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: It's night. Yuri opens his eyes. He wakes up in a strange forest.The small, courageous explorer rides on his bed on casters in this... | Read more »
Space schmup Xenoraid launches on the Ap...
10Tons Xenoraid is out today on the App Store, bringing some high-speed space action to your mobile gadgets just in time for the weekend. The company's last premium title, another sci-fi game titled Neon Chrome, did quite well for itself, so... | Read more »
Star Wars: Force Arena Beginner's G...
Star Wars: Force Arena joined the populous ranks of Star Wars games on mobile today. It's a two-lane MOBA starring many familiar faces from George Lucas's famed sci-fi franchise. As with most games of this nature, Force Arena can be a little obtuse... | Read more »
Mysterium: The Board Game (Games)
Mysterium: The Board Game 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: The official adaptation of the famous board game Mysterium! | Read more »
Sonny (Games)
Sonny 1.0.4 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.4 (iTunes) Description: Reimagined for iOS, cult-hit RPG Sonny brings challenging turn-based combat that requires strategy and mastery of each new skill to... | Read more »

Price Scanner via MacPrices.net

CalcTape for macOS 1.2 Adding Machine App for...
schoettler Software has announced CalcTape 1.2, an update to their desktop calculator for macOS. When it comes to adding long columns of numbers, doing complex calculations or playing around with... Read more
New MacBooks And MacBook Pros WIth Kaby Lake...
Digitimes’ Joseph Tsai cites a Chinese-language Economic Daily News (EDN) report that unnamed market watchers are predicting Apple MacBook shipments to grow 10 percent in 2017, and projecting 15... Read more
New 2016 13-inch MacBook Pros on sale for up...
B&H Photo has the new 2016 13″ MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.9GHz/512GB Touch Bar MacBook Pro... Read more
New 15-inch Touch Bar MacBook Pros in stock a...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
Opera Announces Neon Concept Browser For Mac
Opera is inviting users to get a glimpse of what Opera for computers could become with its Opera Neon browser concept. Each Opera Neon feature is described as “an alternate reality” for the Opera... Read more
Tellini Releases TabView 3.0 Missing Tool fo...
Tellini has announced the release of TabView 3.0. TabView has been the first macOS viewer for PowerTab tablatures. PowerTab is a well-known and widely adopted tablature editor for Windows systems and... Read more
13-inch 1.6GHz/128GB MacBook Air on sale for...
Overstock.com has the 1.6GHz/128GB 13″ MacBook Air on sale for $130 off MSRP including free shipping: - 13″ 1.6GHz/128GB MacBook Air (MMGF2LL/A): $869.99 $130 off MSRP Their price is the lowest... Read more
12-inch 32GB Space Gray iPad Pro on sale for...
B&H Photo has 12″ Space Gray 32GB WiFi Apple iPad Pros on sale for $55 off MSRP including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $744.44 $55 off... Read more
9-inch 32GB Space Gray iPad Pro on sale for $...
B&H Photo has the 9.7″ 32GB Space Gray Apple iPad Pro on sale for $549 for a limited time. Shipping is free, and B&H charges NY sales tax only. Read more
Apple iMacs on sale for up to $120 off MSRP,...
B&H Photo has 21″ and 27″ Apple iMacs on sale for up to $120 off MSRP, each including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2199 $100 off MSRP - 27″ 3.2GHz/1TB Fusion iMac... Read more

Jobs Board

*Apple* Retail - Multiple Positions (Multi-L...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Stamford, CT We have immediate job openings for several Desktop Support Technicians with one of our most well-known Read more
*Apple* macOS Systems Integration Administra...
…most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing Read more
*Apple* Premier Retailer - Service Technicia...
DescriptionSimply Mac is the largest premier retailer for Apple products and solutions. At Simply Mac we are all Apple , all the time. Same products. Same prices. Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.