TweetFollow Us on Twitter

Nov 97 - Getting Started

Volume Number: 13 (1997)
Issue Number: 11
Column Tag: Getting Started

VerySimpleText, Version 2

by Dave Mark , Copyright1997, All Rights Reserved

Three months ago, the August Getting Started column featured a program called VerySimpleText. We built this first version of VerySimpleText using ProjectBuilder and InterfaceBuilder. We started off by editing the nib file (the first version of VerySimpleText wrapped its entire user interface into a single nib file).

We added a Format submenu to the application's default menu, thus adding a series of powerful font, text, and page manipulation features to VerySimpleText. This was done by dragging a Format menu from the menu palette in the palette window.

We also added a scrollable text area (implemented by the NSScrollView class) to the default application window. We did this by dragging a scrollable text view from the DataViews portion of the palette window. We used the NSScrollView inspector to set the autosizing for this view so the scrollable text view grew and shrank along with its containing window. We used InterfaceBuilder's Test Interface feature to test out the window, making sure it looked and behaved as we wanted it to.

Next, we added an info panel (an about box) to VerySimpleText, along with a menu item to bring up the info panel. We edited an existing menu item (Info Panel...) to create our "About VerySimpleText..." item. We used the NSMenuItem inspector to enable the item (unchecking the disabled checkbox, actually). To create the panel itself, we used the Windows portion of the palette window and dragged out our new window, changing the name of the window instance in the nib window and the window's title in the inspector. We also used the palette window to drag some default text into the new info panel.

Once the about panel was built, we created an AboutPanelController class which brought up the about panel when the "About VerySimpleText..." item was selected. Working in the Classes tab within the nib window, we first subclassed NSObject, then created one outlet (abtWindow) and one action (show:). As a reminder, think of an outlet as a variable or object you want associated with your class. When InterfaceBuilder generates the source code for this class, outlets are declared in the header file as type id. An action is a method. In this case, the show: method will bring up the about panel.

Once we were done with our nib file, we told InterfaceBuilder to generate the source files for this project and to add them to the project.

Our next step was to link the "About VerySimpleText..." menu item to the AboutPanelController so when it was selected, the show: method would get called and the panel would appear. First, we instantiated our newly created AboutWindowController class. The instance appeared in the nib window's Instances tab. We then control-dragged from the "About VerySimpleText..." menu item (it's in the menu itself) to the AboutWindowController instance in the nib window. In the inspector window, we clicked the connect button to establish this link. Now, when the "About VerySimpleText..." item is selected, the AboutWindowController's show: method will be called.

Next, we control-dragged from the AboutWindowController instance to our AboutWindow instance. When the link appeared, we moved to the inspector window and clicked on the abtWindow outlet and clicked the Connect button to establish the link. This links the AboutWindowController's abtWindow variable to the AboutWindow. We added a line to the show: method to bring up the window:

- (void)show:(id)sender
{
	[abtWindow makeKeyAndOrderFront:self];
}

The Model, View, Controller Paradigm

Before we move on to this month's additions to VerySimpleText, I thought it might be useful to talk about the Model, View, Controller paradigm, described in Discovering OpenStep: A Developer Tutorial. The Model, View, Controller paradigm is also known as MVC. MVC originated with Smalltalk-80. It categorizes objects as either models, views, or controllers.

Models are objects that emulate some process or represent some knowledge-base. For example, an Employee object represents the knowledge or data associated with an employee. It is a model of an employee. A waterworks object might model the process of converting waste water to clean water and might include the data associated with that process. In general, a model object does not have a user interface. A model object may be distributable and persistent. A model class may be reusable and portable.

View objects are the user interface of your application. Anything displayed by your application is displayed in a view. For example, a window, editable, static, or scrolling text area, button, and scroll bar are all examples of view objects. View objects have no special knowledge of the data they display. In OpenStep, the Application Kit contains a complete set of view objects, all of them designed independent of any model objects. As is evidenced by the Application Kit, view objects are reusable.

Controller objects are the mediators between model objects and view objects. Typically, you'll have one controller object per window (or, possibly, a single controller for your entire application). Your controller object communicates between a model object and its representative view object. For example, an employeeController might use data from an employee object and use that data to create a visible representation of that employee within a view object. At the application level, a controller object would take care of tasks such as loading nib files and acting as a delegate for a window or application.

Delegates

Delegates allow you to provide methods that get called by a class without actually having to subclass the class. Classes which allow delegates feature a set of delegation methods. For example, the NSWindow class features a delegation method called windowWillClose. In this month's sample program, we're going to create a class called Document which will act as an NSWindow delegate. When the NSWindow object gets ready to close, it first calls the delegate's windowWillClose method (assuming the delegate provides such a method). When we define the Document class, we'll provide a windowWillClose method so you can see how this works. You might want to take a look at the NSApplication and NSWindow classes. Their delegation methods are listed at the end of their respective files.

Loading A Nib File

As you've already seen, every application comes with at least one nib file. The nib file is similar to a Macintosh resource file, though it has much more of an object orientation. In fact, one of the primary things stored in a nib file is a set of archived objects. The information in the nib file includes information about each object (like object size and location). It also reflects the position of each object in the overall object hierarchy as well as details about connections between objects in the hierarchy (connections such as the ones we created in the August version of VerySimpleText).

An important part of the object hierarchy is the File's Owner object. Figure 1 shows VerySimpleText's main nib file with the icon representing the File's Owner object in the upper left corner of the Instances tab. The File's Owner sits at the top of each nib file's archived object hierarchy and comes into play when you want to load a nib file other than the main nib file (which is loaded for you automatically).

Figure 1. VerySimpleText's main nib file, showing the File's Owner object.

This line of code:

[NSBundle loadNibNamed:@"NEXTSTEP_Document" owner:self]

loads a nib file named "NEXTSTEP_Document.nib" and sets the File's Owner of the loaded nib file to point to the specified File's Owner. For example, in this month's sample program, we'll define a Document class and we'll tell InterfaceBuilder that the Document class will act as the File's Owner in "NEXTSTEP_Document.nib". Before the nib file can be loaded, we instantiate a Document object. In the Document's init method, we'll call the method loadNibNamed, passing in the nib file name "NEXTSTEP_Document.nib", as well as the object reference self, which refers to the Document object. This second parameter is used as the newly opened nib file's owner.

And Now, Addint to Verysimpletext

Hopefully, the quick review above brought you back up to speed on the overall structure of the August version of VerySimpleText and gave you enough background to follow this month's changes. This month, we're going to add the ability to handle multiple documents to VerySimpleText. We'll tie this functionality to the Document menu's New item. You'll want to start off with a copy of the August version of VerySimpleText. Be sure to keep a copy of the original around just in case. I named my original folder VerySimpleText.01 and named the copy VerySimpleText.02. Once you've made your copy, open the ProjectBuilder project in the duplicate.

  • Find the file PB.project in the duplicate directory and double-click it to launch ProjectBuilder.
  • Next, we're going to create a new nib file.
  • Click the ProjectBuilder Interfaces item, then double-click the NEXTSTEP_VerySimpleText.01.nib file.
  • The selected nib file will be opened in InterfaceBuilder. Now to create the new file:
  • In InterfaceBuilder, select Document/New Module/New Empty.

A new, untitled nib window will appear (See Figure 2). If you click on the Instances tab, you'll see two instances. One is the File's Owner. If you click on the File's Owner icon, the inspector window (attributes popup) will list a set of classes and the NSObject class will be selected. We'll revisit this a bit later in the column.

Figure 2. The new, untitled nib file.

  • Click on the Classes tab in the new nib window.
  • Select NSObject.
  • Select Classes/Subclass.
  • Rename the new subclass from MyNSObject to Document.
  • Save the new nib file.

You'll name your new nib file as NEXTSTEP_Document.nib (you can leave off the .nib if you like). Be sure to save the new nib file in the same directory as the main nib file, NEXTSTEP_VerySimpleText.01.nib (Figure 3).

Figure 3. Saving the new nib file.

  • When asked, say yes to insert the file in the project.

You will now be in ProjectBuilder.

  • Go back to InterfaceBuilder.
  • Be sure the Document line in the nib file's Classes tab is hilited.
  • Click on the outlet icon (the left of the two icons).
  • Be sure that the Outlets line is highlighted.
  • Select Classes/Add Outlet.
  • Change the outlet name myOutlet to window.
  • Click on the outlet icon to get out of outlet mode.
  • Select Classes/Create Files.
  • When asked whether we want to create a Document.h and .m file, click Yes.
  • When asked to insert files in project, click Yes.
  • We'll be back in Project Builder.

Go back to InterfaceBuilder.

  • Back in the nib window, click on the Instances tab.
  • Click on File's Owner.

In the inspector window, the class NSObject will be selected.

  • Scroll up to Document and select it.

Document will now be highlighted when you click on File's Owner.

  • Bring the original nib file to the front.
  • In the Instances tab, select the MyWindow icon.
  • Select Edit/Cut.
  • When you are asked Do you really want to delete the window?", click Delete.
  • Bring the new nib file to the front.
  • Select Edit/Paste.

The MyWindow icon should appear in the new nib window and the window itself should reappear.

  • Hold down the control key and drag from File's Owner icon to MyWindow icon.
  • When you let go, go to the inspector window and click Connect.

You've just connect MyWindow to the File Owner's outlet (in this case, the Document classes' window variable).

  • In the NEXTSTEP_Document.nib window, control drag from MyWindow to File's Owner.
  • Select the word delegate in the left-hand column.
  • Click the Connect button.

You've just made Document MyWindow's delegate.

  • Select Document/Save.

We are now done with this nib window.

  • Bring the old nib file to the front.
  • Click on the nextstep menu to bring it to the front.
  • Select Tools/Palettes/Palettes.
  • Select the leftmost palette (Menus).
  • Drag a Document menu into the nextstep menu, just below Info

The new Document menu will appear, just to the right of the nextstep menu.

  • In the Document menu, click on New.
  • In the inspector window, select attributes from the popup menu.
  • Click the Disabled checkbox so it is unchecked.
  • In the Document menu, click on Close.
  • In the inspector window, click the Disabled checkbox so it is unchecked.
  • Click on the old nib window and select the Classes tab.
  • Click on NSObject.
  • Select Classes/Subclass.
  • Rename subclass to AppDelegate.
  • Click on action icon (on right).
  • Click on Actions line, select Classes/Add Action.
  • Rename new Action to new:.
  • Click off the Actions icon.
  • Click Classes/CreateFiles.
  • Create the files (answer yes to create files and add to project).

We are now back in ProjectBuilder.

  • Go back to InterfaceBuilder.
  • In the old nib file's classes tab, select AppDelegate line.
  • Select Classes/Instantiate.
  • In the instances tab, control-drag from File's Owner to AppDelegate.
  • In the inspector window, be sure delegate is selected, then click Connect.

We have just marked AppDelegate as the NSApplication delegate. We won't implement any of the NSApplication delegate methods in our AppDelegate code, but we could. Take a look at NSApplication and take a few of the delegation methods for a spin.

  • Go to the nextstep menu and control-drag from New to AppDelegate in the old nib window.
  • In the inspector window, select new from the actions list, then click Connect.

We've just connected the new menu item to the AppDelegate's new: method.

  • Select Document/Save.

OK. That's it for the nib files. Now all we need to do is add a bit of code and we are on our way.

  • Go to ProjectBuilder.
  • Under Classes, select Document.m.

Here's what the code looks like now:

#import "Document.h"

@implementation Document

@end
  • Edit the code so it looks like this:
#import "Document.h"

@implementation Document

- init
{
	//Find the nib and load it in.  This instance will be the
	//File's Owner object, so we pass ourself as owner
	if (![NSBundle loadNibNamed:
					@"NEXTSTEP_Document" owner:self])
	{
		//for whatever reason, we failed.  Clean up and go
		NSLog(@"Failed to load Document.nib");
		[self release];
		return nil;
	}
	return self;
}

//Since the Document is the Windows's delegate,
//it will get the following
//method called whenever the window closes.  
- (void)windowWillClose:(NSNotification *)aNotification
{
	//We remove ourself as the delegate as
	//we are going to release ourselves
	[window setDelegate:nil];
	//Let garbage collection do the actual deletion
	[self autorelease];
}

@end
  • Under Classes, select AppDelegate.m.

Here's what the code looks like now:

#import "AppDelegate.h"

@implementation AppDelegate

- (void)new:(id)sender
{
}

@end

Edit the code so it looks like this:

#import "AppDelegate.h"

@implementation AppDelegate

- (void)new:(id)sender
{
}

@end

Change it to look like this:

#import "AppDelegate.h"
#import "Document.h"

@implementation AppDelegate

- (void)new:(id)sender
{
	//Just instantiate a Document. It will know what to do.
	[[Document alloc] init];
}

@end
  • Click on the hammer icon to bring up the project build window.
  • Click on the hammer again to build the project.
  • When prompted with the Save Modified Files dialog, click Save and build.
  • Assuming the build succeeds, click on the monitor icon to bring up the launch window.
  • Click on the monitor icon in the launch window to run the application.

When the application runs, select Document/New to create new windows.

Till Next Month...

Between delegates, File's Owner, and nib file loading, you've learned a lot this month. Be sure to spend some time looking at NSWindow and NSApplication to get a feel for the power of delegation. This will give you something to chew on until we have releases of Rhapsody and Rhapsody developer tools.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Pack a magnifying glass and practice you...
Somehow it has already been a year since Torchlight: Infinite launched, and XD Games is celebrating by blending in what sounds like a truly fantastic new update. Fans of Cthulhu rejoice, as Whispering Mist brings some horror elements, and tests... | Read more »
Summon your guild and prepare for war in...
Netmarble is making some pretty big moves with their latest update for Seven Knights Idle Adventure, with a bunch of interesting additions. Two new heroes enter the battle, there are events and bosses abound, and perhaps most interesting, a huge... | Read more »
Make the passage of time your plaything...
While some of us are still waiting for a chance to get our hands on Ash Prime - yes, don’t remind me I could currently buy him this month I’m barely hanging on - Digital Extremes has announced its next anticipated Prime Form for Warframe. Starting... | Read more »
If you can find it and fit through the d...
The holy trinity of amazing company names have come together, to release their equally amazing and adorable mobile game, Hamster Inn. Published by HyperBeard Games, and co-developed by Mum Not Proud and Little Sasquatch Studios, it's time to... | Read more »
Amikin Survival opens for pre-orders on...
Join me on the wonderful trip down the inspiration rabbit hole; much as Palworld seemingly “borrowed” many aspects from the hit Pokemon franchise, it is time for the heavily armed animal survival to also spawn some illegitimate children as Helio... | Read more »
PUBG Mobile teams up with global phenome...
Since launching in 2019, SpyxFamily has exploded to damn near catastrophic popularity, so it was only a matter of time before a mobile game snapped up a collaboration. Enter PUBG Mobile. Until May 12th, players will be able to collect a host of... | Read more »
Embark into the frozen tundra of certain...
Chucklefish, developers of hit action-adventure sandbox game Starbound and owner of one of the cutest logos in gaming, has released their roguelike deck-builder Wildfrost. Created alongside developers Gaziter and Deadpan Games, Wildfrost will... | Read more »
MoreFun Studios has announced Season 4,...
Tension has escalated in the ever-volatile world of Arena Breakout, as your old pal Randall Fisher and bosses Fred and Perrero continue to lob insults and explosives at each other, bringing us to a new phase of warfare. Season 4, Into The Fog of... | Read more »
Top Mobile Game Discounts
Every day, we pick out a curated list of the best mobile discounts on the App Store and post them here. This list won't be comprehensive, but it every game on it is recommended. Feel free to check out the coverage we did on them in the links below... | Read more »
Marvel Future Fight celebrates nine year...
Announced alongside an advertising image I can only assume was aimed squarely at myself with the prominent Deadpool and Odin featured on it, Netmarble has revealed their celebrations for the 9th anniversary of Marvel Future Fight. The Countdown... | Read more »

Price Scanner via MacPrices.net

Every model of Apple’s 13-inch M3 MacBook Air...
Best Buy has Apple 13″ MacBook Airs with M3 CPUs in stock and on sale today for $100 off MSRP. Prices start at $999. Their prices are the lowest currently available for new 13″ M3 MacBook Airs among... Read more
Sunday Sale: Apple iPad Magic Keyboards for 1...
Walmart has Apple Magic Keyboards for 12.9″ iPad Pros, in Black, on sale for $150 off MSRP on their online store. Sale price for online orders only, in-store price may vary. Order online and choose... Read more
Apple Watch Ultra 2 now available at Apple fo...
Apple has, for the first time, begun offering Certified Refurbished Apple Watch Ultra 2 models in their online store for $679, or $120 off MSRP. Each Watch includes Apple’s standard one-year warranty... Read more
AT&T has the iPhone 14 on sale for only $...
AT&T has the 128GB Apple iPhone 14 available for only $5.99 per month for new and existing customers when you activate unlimited service and use AT&T’s 36 month installment plan. The fine... Read more
Amazon is offering a $100 discount on every M...
Amazon is offering a $100 instant discount on each configuration of Apple’s new 13″ M3 MacBook Air, in Midnight, this weekend. These are the lowest prices currently available for new 13″ M3 MacBook... Read more
You can save $300-$480 on a 14-inch M3 Pro/Ma...
Apple has 14″ M3 Pro and M3 Max MacBook Pros in stock today and available, Certified Refurbished, starting at $1699 and ranging up to $480 off MSRP. Each model features a new outer case, shipping is... Read more
24-inch M1 iMacs available at Apple starting...
Apple has clearance M1 iMacs available in their Certified Refurbished store starting at $1049 and ranging up to $300 off original MSRP. Each iMac is in like-new condition and comes with Apple’s... Read more
Walmart continues to offer $699 13-inch M1 Ma...
Walmart continues to offer new Apple 13″ M1 MacBook Airs (8GB RAM, 256GB SSD) online for $699, $300 off original MSRP, in Space Gray, Silver, and Gold colors. These are new MacBook for sale by... Read more
B&H has 13-inch M2 MacBook Airs with 16GB...
B&H Photo has 13″ MacBook Airs with M2 CPUs, 16GB of memory, and 256GB of storage in stock and on sale for $1099, $100 off Apple’s MSRP for this configuration. Free 1-2 day delivery is available... Read more
14-inch M3 MacBook Pro with 16GB of RAM avail...
Apple has the 14″ M3 MacBook Pro with 16GB of RAM and 1TB of storage, Certified Refurbished, available for $300 off MSRP. Each MacBook Pro features a new outer case, shipping is free, and an Apple 1-... Read more

Jobs Board

*Apple* Systems Administrator - JAMF - Activ...
…**Public Trust/Other Required:** None **Job Family:** Systems Administration **Skills:** Apple Platforms,Computer Servers,Jamf Pro **Experience:** 3 + years of Read more
IT Systems Engineer ( *Apple* Platforms) - S...
IT Systems Engineer ( Apple Platforms) at SpaceX Hawthorne, CA SpaceX was founded under the belief that a future where humanity is out exploring the stars is Read more
Nurse Anesthetist - *Apple* Hill Surgery Ce...
Nurse Anesthetist - Apple Hill Surgery Center Location: WellSpan Medical Group, York, PA Schedule: Full Time Sign-On Bonus Eligible Remote/Hybrid Regular Apply Now Read more
Housekeeper, *Apple* Valley Village - Cassi...
Apple Valley Village Health Care Center, a senior care campus, is hiring a Part-Time Housekeeper to join our team! We will train you for this position! In this role, Read more
Sublease Associate Optometrist- *Apple* Val...
Sublease Associate Optometrist- Apple Valley, CA- Target Optical Date: Apr 20, 2024 Brand: Target Optical Location: Apple Valley, CA, US, 92307 **Requisition Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.