TweetFollow Us on Twitter

TinyViewer

Volume Number: 19 (2003)
Issue Number: 5
Column Tag: Programming

Getting Started

TinyViewer

by Dave Mark

When I first started programming the Mac, lo those many years ago, one of the earliest programs I wrote was a teeny app called PictViewer. PictViewer put up a standard document window, with scroll bars and a grow box, and drew a pict image, centered in the window. The first version just displayed the image, clipping it to the window FrameRect as needed. The scroll bars were mere decoration. When I tackled a more advanced version of PictViewer, I added the callback routines and other code to bring the scroll bars to life. In still a later incarnation, I added the ability to drag and drop an image on a PictViewer window.

As I was putting the finishing touches on this project, I remember thinking, "gee, it sure would be nice if all this was just a bit easier." Frameworks like PowerPlant did go a long way towards stringing all the pieces together, but there was still a lot of hand-coding to be done and lots of room for error.

As you'll see in this month's program, TinyViewer, the combination of the Objective-C runtime and tools like Interface Builder and Project Builder take working with objects to the next level.

Getters, Setters, and Key Value Coding

Before we dig into TinyViewer, I'd like to take a moment to emphasize a point I made in my March column. The issue was a naming convention for accessor functions. I suggested that you name your getter methods to match the name of the instance variable being retrieved, then put the word "set" in front of that (be sure to cap the first letter after the word "set") to name the setter function. Here's the example I gave:

- (int)height;        // Returns the value of the height field
- (void)setHeight:(int)h;    // Sets the height field to
                                     // the value in h

Bill Cheeseman, famous ex-attorney (remember the John Travolta movie A Civil Action? Bruce Norris played Bill in the movie. True.) and Cocoa aficionado (I highly recommend his most excellent book, Cocoa Recipes for Mac OS X: The Vermont Recipes), took the time to discuss the importance of this convention with me.

In a nutshell, consider this naming convention mandatory, not optional. In Bill's words:

    "The -height and -setHeight: getter and setter naming conventions are expected by many features of the AppKit and Foundation. While these are optional naming "conventions" from the perspective of Objective-C as a language, they are effectively mandatory if you want to use the Cocoa frameworks. You will lose a lot of important Cocoa framework functionality if you don't follow these naming conventions.

    The most important aspect of the Cocoa frameworks that depends on following these naming conventions is the key-value coding protocol. Look up key-value coding in the Cocoa documentation, and read the class reference document for the NSKeyValueCoding informal protocol in the Foundation frameworks. Several important Cocoa technologies use key-value coding, such as AppleScript. If you don't follow this naming convention for your accessors, you will not be able to take advantage of Cocoa's automatic support for AppleScriptability. There are several other areas where similar dependence on key-value coding requires you to follow these naming conventions.

    Basically, key-value coding lets you write code that calls methods by giving the names of instance variables as strings. This enables you to write a single method which will call other methods based on the strings you provide, rather than having to make actual method calls (er, "to send actual messages") in a long case statement. Because of this, the actual method calls ("messages") can be determined at run time, not hard-coded at compile time. Furthermore, key-value coding gives the separate, added benefit of providing the data in the correct type without your having to code type coercions in a case statement."

Thanks, Bill! As you develop more confidence with Objective-C and Cocoa, spend some time digging through the key-value coding doc and examples. Here's a good link to start with:

http://developer.apple.com/techpubs/macosx...

OK, let's get back to this month's program...

TinyViewer

Every time I sit down to tackle a new Mac programming environment or methodology, I always seem to find myself coming back to PictViewer. How am I going to get PictViewer up and running with this new setup. As soon as I had my first working version of Project Builder installed, the first thing I did was dig through the Cocoa doc, looking for the classes I'd need to master to create a resizable window, with scrollbars, I could usein which I could display an image. Once I figured that out, I'd then tackle some drag-and-drop classes so I could add that feature to the program.

Little did I know how easy (and cool) this would turn out to be.

Create the TinyViewer Project

Launch Project Builder and create a new project of type Cocoa Application. Name the app TinyViewer and save. In the Project Builder Files pane, click to open the triangle to the left of Resources, then open the triangle to the left of MainMenu.nib. This will reveal an item named English (assuming you are on an English-based Mac).

The .nib file is an Interface Builder file. Interface Builder is sort of like ResEdit on steroids. With it, you can customize all your favorite objects and encode them for later decoding when your program is actually run. The item named English in the Project Builder Files tab refers to the English-localized nib file. Figure 1 shows the Finder listing of my version of TinyViewer. Notice the directory named English.lproj and the file MainMenu.nib within that directory. That's the English version of the nib file, the one we'll be working with in this column.


Figure 1. The English.lproj folder inside the project folder.

Figure 2 shows a Terminal listing showing a localized application on my hard drive. I start by going into the /Applications directory, the doing a cd into the sub-directory Clock.app. If I looked at /Applications in a Finder window, Clock.app would just appear as a single application file. In reality, your packaged applications are a series of files, all rolled under a single directory, in this case named Clock.app. As Figure 2 shows, if you make your way down into /Applications/Clock.app/Contents/, you'll see a number of different files and directories, including a directory for each localized version of the app. You should definitely fire up Terminal and try this for yourself. Dive down into your favorite app, then look for English.lproj.


Figure 2. Follow the terminal commands to find your way to the localized .nib files

Editing the .nib File

Double-click on TinyViewer/Resources/MainMenu.nib/English in the project window Files tab. This will open your .nib file in Interface Builder. You'll likely see 4 Interface Builder windows appear. The window labeled Window (Figure 3) represents your app's main window. The window labeled MainMenu.nib - MainMenu (Figure 4) contains your app's menu bar. The window labeled MainMenu.nib (Figure 5) acts as a central repository for the resources/instances you'll be creating. And the window labeled Cocoa - Other (Figure 6) is a palette window.


Figure 3. The default TinyViewer window, shrunk for convenience.


Figure 4. The default application menubar.


Figure 5. The main .nib file navigation window.


Figure 6. The palettes window.

Note the row of icons at the top of the palette window (Figure 6). Clicking on one of the icons changes the set of items available from that section of the palette. Currently, there are 10 palette icons. In order, they are Menus, Views, Other, Windows, Data, Containers, GraphicsViews, AppleScript, MSFFormatterPalette, and Sherlock. Our focus will be on the third icon from the left, the Other palette. Click on the Other icon and your palette window should look like the one shown in Figure 6.

Click and drag an NSImageView out of the palette window into the window named Window. If you hover your cursor over an item in the palette window, a "tool tip" will appear that tells you the item type. Drag the NSImageView towards the upper-left corner of the Window window until a pair of crossed blue lines appear (see Figure 7).


Figure 7. Dragging an NSImageView onto your main window.

Next, click on the NSImageView icon to select it. 8 grow handles will appear. Drag the lower right grow handle to grow the NSImageView until the crossed blue lines appear as you approach the lower right corner of the window. The net result will be an NSImageView inset in the window about the thickness of a scrollbar on all four sides.

Now, let's bring up an inspector window and customize our NSImageView. Select Show Info from the Tools menu. The NSImageView Info window will appear (Figure 8). The Info window allows you to modify the currently selected object. In this case, we're inspecting our NSImageView object.


Figure 8. The Info window for our NSImageView.

Take a look at Figure 8. Your settings should look like this. Be sure the Editable checkbox is checked. This will enable "drag and drop". In fact, when you take the interface for a spin, try testing the interface with and without the Editable checkbox checked.

Next, select Size from the popup menu and compare your settings to those shown in Figure 9. Note that the Layout Rect fields will not necessarily match. Not to worry. It's just the difference between our window sizes. What's important is the Autosizing settings. To change those, click on the two lines in the inner square till each line turns into a pair of springs. Again, when you test the interface, play with these settings. Try it with one line and one spring, just to see what affect this has.


Figure 9. The NSImageView Info window, this time showing the Size settings.

Testing the Interface

OK, now let's take the interface for a spin. Select Test Interface from the File menu. Your window will appear, with an NSImageView area centered in the window. Click on a picture and drag it to the NSImageView field. The image should appear centered in the window. When you resize the window, the image should resize until it reaches its full size.

Play, play, play. Drag the image back out of the window and onto the desktop. A clipping file should appear. Double-click it and you can view your image directly in the Finder. Cool!

To exit the application, just select Quit from the File menu.

You should now be back in Interface Builder. Select Save from the File menu to save the .nib file. Now go back into Project Builder and run TinyViewer. Notice that TinyViewer appears in the dock as an icon, the main menu is titled "TinyViewer", your window appears, and is fully functional. Very cool!!

    There's a terrific new Cocoa book out there you should definitely check out. It's called Cocoa Programming by Scott Anguish, Erik M. Buuck, and Donald A. Yacktman, published by Sams. You can find it at http://www.devdepot.com/books.html.

    I can't say enough about Cocoa Programming. Chapter 1 has one of the clearest breakdowns of the Mac OS X development universe I've yet read. There's great coverage of Objective C, design patterns, memory management, strings, encoding/decoding, exhaustive coverage of the Cocoa frameworks, and just about anything else you might think of. And there, nestled in Chapter 3 you'll find the Cocoa Programming treatment of an NSImageView app. Great stuff. My highest recommendation.

Till Next Month...

Next month, we'll do more with Interface Builder, including exploring the details of the Info window and customizing the menu bar. See you then...


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. Be sure to check out Dave's web site at http://www.spiderworks.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

The best scanner app on mobile
People always say that the best camera is the one you have with you. Well, the same is true with scanners, and your phone can be a pretty great tool for scanning receipts and other documents while you're on the go. [Read more] | Read more »
MARVEL Avengers Academy guide - How to g...
MARVEL Avengers Academy lets you build your own superhero school and fill it with heroes from the Marvel universe. It can be a little slow going to get your school's attendance up though, so we've gathered together somesome tips to help you do this... | Read more »
Shadow Blade: Reload guide - How to hack...
Shadow Blade: Reload is the kind of action-platformer that would have happily sucked up hours of your time on a console a few years back.Now, you can take it with you wherever you go, and its mobile conversion is not too shabby at all. To help you... | Read more »
Tomb of the Mask guide - How to increase...
Tomb of the Mask is a great endless arcade game from Happymagenta in which quick reflexes and a persistent attitude can go a long way toward earning a top score. Check out these tips to see if you can give yourself an edge on the leaderboards. [... | Read more »
Smooth Operator! (Games)
Smooth Operator! 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Smooth Operator is a weird, weird two-player kissing game. Squeeze in for 2 player fun on a single iPad, creating awkward... | Read more »
Sinless: Remastered (Games)
Sinless: Remastered 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
_PRISM Guide - How to solve those puzzle...
_PRISM is a rather delightful puzzle game that’s been tailor made for touch screens. While part of the fun is figuring things out as you go along, we thought we’d offer you a helping hand at getting in the right mindset. Don’t worry about messing... | Read more »
Fractal Space (Games)
Fractal Space 1.3.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.3.1 (iTunes) Description: Live the memorable experience of Fractal Space, a unique first person adventure & puzzle game by Haze Games! Will you... | Read more »
Set off on an adventure through the Cand...
Like match three puzzlers? If so, Jelly Blast, the innovative iOS and Android game which launched last year, is worth a look. Jelly Blast sees you head off on an epic adventure through the Candy Kingdom with your friends Lily, Mr. Hare, and Mr.... | Read more »
Ellipsis - Touch. Explore. Survive. (...
Ellipsis - Touch. Explore. Survive. 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

cb Hardcase – Handmade and Premium Protective...
Baden-Baden, Germany based company cb innovations has introduced the new cb Hardcase for iPhone. Featuring fine Italian Premium leather that makes for a unique look and feel, the cb Hardcase... Read more
Sale! B&H Photo offers 12-inch Retina Mac...
B&H Photo has 12″ Retina MacBooks on sale for $300 off MSRP for a limited time. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Gray Retina MacBook: $999 $300 off MSRP - 12″ 1.... Read more
App Annie Reveals Future of the App Economy:...
App Annie, a San Francisco based mobile app data and insights platform, has launched its first comprehensive app economy forecast. This new offering will provide brands, agencies, investors and app... Read more
Apple restocks Certified Refurbished Mac mini...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
What iPad Pro Still Needs To Make It Truly Pr...
I love my iPad Air 2. So much that I’m grudgingly willing to put up with its compromises and limitations as a production tool in order to take advantage of its virtues. However, since a computer for... Read more
21-inch 3.1GHz 4K on sale for $1399, $100 off...
B&H Photo has the 21″ 3.1GHz 4K iMac on sale $1399 for a limited time. Shipping is free, and B&H charges NY sales tax only. Their price is $100 off MSRP: - 21″ 3.1GHz 4K iMac (MK452LL/A): $... Read more
Apple price trackers, updated continuously
Scan our Apple Price Trackers for the latest information on sales, bundles, and availability on systems from Apple’s authorized internet/catalog resellers. We update the trackers continuously: - 15″... Read more
Save up to $240 with Apple Certified Refurbis...
Apple is now offering Certified Refurbished 12″ Retina MacBooks for up to $240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
Apple refurbished Time Capsules available for...
Apple has certified refurbished Time Capsules available for $120 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $179, $120 off - 3TB... Read more

Jobs Board

Infrastructure Engineer - *Apple* /Mac - Rem...
…part of a team Requires proven problem solving skills Preferred Additional: Apple Certified System Administrator (ACSA) Apple Certified Technical Coordinator (ACTC) Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
*Apple* Reporter - Business Insider, Inc. (U...
Business Insider is looking for a reporter to cover Apple , the biggest and arguably most important company in tech. As our primary Apple reporter, you will: * Read more
Infrastructure Engineer - *Apple* /Mac - Rem...
…part of a team Requires proven problem solving skills Preferred Additional: Apple Certified System Administrator (ACSA) Apple Certified Technical Coordinator (ACTC) Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.