TweetFollow Us on Twitter

More on Xcode

Volume Number: 19 (2003)
Issue Number: 9
Column Tag: Programming

Geeting Started

More on Xcode

by Dave Mark

I must say, I am really enjoying digging into Xcode. I'm impressed with what I've seen so far. The bugs I've encountered have mostly been cosmetic and, I assume, easily fixable. My understanding is that the WWDC release is the only Jaguar release and that all fixes and future releases will be Panther-only.

For the moment, I'll stick with the Jaguar version. As soon as a "for public consumption" version of the Panther Xcode makes its way into my hot little hands, I'll shift permanently into Panther mode.

Editor Window Details

Last month's column started off by opening an existing Project Builder project called Sketch.pbxproj in Xcode and updating the target, creating a new target called Sketch (Upgrade). Go ahead and launch Xcode and open the project. If you are starting from scratch, you'll find Sketch.pbxproj in the directory /Developer/Examples/AppKit/Sketch/. Remember, you can open a project by navigating to the right directory and clicking the Open button. Xcode will find the project file for you.

When the project window appears, click and hold on the Build and Debug icon. After a slight pause, a drop-down menu will appear (see Figure 1). The little triangle to the lower right of an Xcode tool icon is your clue that there's a drop-down menu lurking within. Just remember to hold and wait a hitch for the menu to appear.


Figure 1. The Build and Debug drop-down menu.

Go ahead and select Build and Debug from the drop-down menu. Xcode will build and launch a debug-ready version of Sketch and open the debugger window. As you'd expect, the debugging window allows you to control the debugging process.

Use the Dock to bring Sketch to the front. Click on the rectangles icon in the palette, then click and drag out a rectangle in the main window (see Figure 2). Note that the rectangle that appears is not filled.


Figure 2. Dragging out a rectangle with Sketch.

Now go back to the project window and click on the Project Symbols group (the last group in the Groups & Files column). As you saw last month, this "smart group" lists all the symbols in the project. Type init in the search field to reduce the list of symbols (See Figure 3).


Figure 3. Using the search field to find the init method in SKTGraphic.m.

We're looking for the init method in the file SKTGraphic.m. There are two ways to open this file from the listing in the Project Symbols group. We can click on the Editor icon in the toolbar (the cursor is pointing to this icon in Figure 3) to open an editing pane for that file in the Project Window. Alternatively, we can double-click on the line listing the file we want to open that file in a separate editing window. That's the method we're going to use here.

Figure 4 shows the editor window that appeared when I double-clicked on SKTGraphic.m. At the top of the window is the editor toolbar. Just beneath that is the status bar (in Figure 4 it says Sketch (Upgraded)).


Figure 4. A new editing window listing the file SKTGraphic.m.

Below the status bar is the navigation bar. Towards the left edge of the nav bar is a pair of arrows. These act like the left and right arrows in your browser and are used to move between source files. You'll see how this works in a sec.

If you scan to the right side of the nav bar, you'll see an icon showing a pair of overlapping rectangles, a grey one in front of a white one. This is called the counterpart icon. Click on it to switch between a .m and its corresponding .h file. For example, click the counterpart icon to switch to SKTGraphic.h. Note that the left arrow on the left side of the nav bar is now enabled. You can click it to go back to the file SKTGraphic.m. And, as you'd expect, once you click on the left arrow, the right arrow will be enabled so you can go back to SKTGraphic.h. As promised, just like the arrows in your browser.

As you visit different files in your editor window, they are added to a list, sort of a running history. Immediately to the right of the arrows in your nav bar is a popup listing all the files in this history list. Select a file name and the editor edits that file. Makes sense. The tiny dogear icon immediately to the left of the file name is a dirty flag. If the file is dirty (if it has changed since the last save) the icon is grey. Save the file and it returns to white.

Just to the right of the file name is a colon (":") followed by the current line number (either the beginning of a selection, or the line holding the insertion point). If you want to go to a specific line in a file, you can trial and error it, clicking around using the line number in the nav bar to help you home in on the right line. Or you can select Go to Line... from the Find menu (Command-L) and use that interface to select a specific line or range of lines (See Figure 5).


Figure 5. The Go to Line... command from the Find menu.

Also in the nav bar, just to the right of the file popup menu, lies the function/method popup. As you'd expect, this popup lists all the functions in the current file. Click anywhere inside a function and that function is shown in the popup title. Click on the popup and all the functions/methods in the file are listed in the order in which they appear. Option-click and the functions are listed in alphabetical order, separated by implementation. Give it a try. You'll get it right away.

Next over to the right is the counterpart icon (which we discussed above) followed immediately by the included files popup (it looks like a #) which lets you edit the tree of included files. Figure 6 shows the included files popup for SKTGraphic.m.


Figure 6. The included files popup menu.

To the lower right of the included files popup (at the top of the scroll bar) is the split view toggle. Click on the toggle to create a split in the editing window. Click the toggle again to remove the split. Once you create a split, the split resize control appears between the upper and lower scroll bars. To move the split, just drag this control (See Figure 7). Note that in the current Jaguar release (and presumably the only Jaguar release) of Xcode, the split resize control does not get drawn when you first create a split. Just resize the window a tiny bit and the control will appear.


Figure 7. Dragging the split resize control.

Fix and Continue

One of my favorite Xcode features is Fix-and-Continue. With Mac OS X's built-in support for dynamic linking, you can actually modify your code while it is running and watch the change come to life. Really.

So let's try this out. When you played with Sketch earlier in the column, you dragged out a rectangle and saw that the result was unfilled. If you look through the source code, you'll find that the fill color is white, but the setDrawFill: method is called with the parameter NO. In SKTGraphic.m, here's the init method:

- (id)init {
    self = [super init];
    if (self) {
        _document = nil;
        [self setBounds:NSMakeRect(0.0, 0.0, 1.0, 1.0)];
        [self setFillColor:[NSColor whiteColor]];
        [self setDrawsFill:NO];
        [self setStrokeColor:[NSColor blackColor]];
        [self setDrawsStroke:YES];
        [self setStrokeLineWidth:1.0];
        _origBounds = NSZeroRect;
        _gFlags.manipulatingBounds = NO;
    }
    return self;
}

Pay special attention to lines 6 and 7, which correspond to lines 20 and 21 in the file. If you haven't already, launch Sketch in the debugger. You can click on the Debug spray can in the editing window or debug window's toolbar, or select from the hammer/spraycan icon in the Project Window's toolbar.

Once Sketch launches in debug mode (you can tell the debugger is active because the Terminate and Pause icons will be enabled in the Debug window), drag out a couple of rectangles, just to prove that they are, indeed, unfilled.

Now go back to your editing window for SKTGraphic.m and change line 20 and 21 from:

        [self setFillColor:[NSColor whiteColor]];
        [self setDrawsFill:NO];

to:

        [self setFillColor:[NSColor greenColor]];
        [self setDrawsFill:YES];

Do NOT save. You'll see why in a sec.

Basically, we've changed the fill color from white to green and we've told Sketch that we do want our shapes filled.

Now comes the cool part.

Select Fix from the Debug menu.

Remember not to save!

You'll see a message in the Debug window about compiling and building. Once that settles down, go back to the running Sketch and click and drag out a rectangle. Wait, I've done it for you. Check out Figure 8. As you were expecting, the rectangles are now filled and green.


Figure 8. After the fix is applied, our rects are filled with green. Cool!

Once you are done playing with your new green rects, quit Sketch and rerun it, either as a straight run or via the debugger. Notice that your rectangles are back to being unfilled (you did remember to not save your changes, right?) To me, this is a beautiful way to play with your code. You can make changes, experiment, use Debug/Fix to test out your changes, see what works for you, then save what you want to.

I find dynamic linking fascinating. Fix and Continue works for Objective C, Carbon/C++ or even straight C, so it's available to all Mac OS X APIs and development languages. Though the Xcode team did not create dynamic linking, they did an excellent job rolling it into the environment. Brilliant!

    You may have noticed a scotch-tape dispenser icon in the Debug window with the label Fix. Clicking this icon does the same thing as selecting Fix from the Debug menu. There is a bug (I believe it is fixed in the current Panther release) where the icon is disabled (it just beeps when you click it). Fortunately, the bug does not affect the Fix item in the Debug menu.

Till Next Month...

Whelp, I'm out of space again. <sigh>. There's so much more I want to talk about. Next month, we're going to take the debugger through its paces and we'll also play around with a feature called code completion, one of my very favorite parts of Xcode. See you then...


Dave Mark is a long-time Mac developer and MacTech contributor. Author of more than a dozen books on various Mac-development topics, Dave is all about Xcode these days. Last month's column focused on the basics of opening a Project Builder project, target conversion, and the project window user interface. This month's installment will focus on the editor interface and a demo of fix-and-continue.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Whitethorn Games combines two completely...
If you have ever gone fishing then you know that it is a lesson in patience, sitting around waiting for a bite that may never come. Well, that's because you have been doing it wrong, since as Whitehorn Games now demonstrates in new release Skate... | Read more »
Call of Duty Warzone is a Waiting Simula...
It's always fun when a splashy multiplayer game comes to mobile because they are few and far between, so I was excited to see the notification about Call of Duty: Warzone Mobile (finally) launching last week and wanted to try it out. As someone who... | Read more »
Albion Online introduces some massive ne...
Sandbox Interactive has announced an upcoming update to its flagship MMORPG Albion Online, containing massive updates to its existing guild Vs guild systems. Someone clearly rewatched the Helms Deep battle in Lord of the Rings and spent the next... | Read more »
Chucklefish announces launch date of the...
Chucklefish, the indie London-based team we probably all know from developing Terraria or their stint publishing Stardew Valley, has revealed the mobile release date for roguelike deck-builder Wildfrost. Developed by Gaziter and Deadpan Games, the... | Read more »
Netmarble opens pre-registration for act...
It has been close to three years since Netmarble announced they would be adapting the smash series Solo Leveling into a video game, and at last, they have announced the opening of pre-orders for Solo Leveling: Arise. [Read more] | Read more »
PUBG Mobile celebrates sixth anniversary...
For the past six years, PUBG Mobile has been one of the most popular shooters you can play in the palm of your hand, and Krafton is celebrating this milestone and many years of ups by teaming up with hit music man JVKE to create a special song for... | Read more »
ASTRA: Knights of Veda refuse to pump th...
In perhaps the most recent example of being incredibly eager, ASTRA: Knights of Veda has dropped its second collaboration with South Korean boyband Seventeen, named so as it consists of exactly thirteen members and a video collaboration with Lee... | Read more »
Collect all your cats and caterpillars a...
If you are growing tired of trying to build a town with your phone by using it as a tiny, ineffectual shover then fear no longer, as Independent Arts Software has announced the upcoming release of Construction Simulator 4, from the critically... | Read more »
Backbone complete its lineup of 2nd Gene...
With all the ports of big AAA games that have been coming to mobile, it is becoming more convenient than ever to own a good controller, and to help with this Backbone has announced the completion of their 2nd generation product lineup with their... | Read more »
Zenless Zone Zero opens entries for its...
miHoYo, aka HoYoverse, has become such a big name in mobile gaming that it's hard to believe that arguably their flagship title, Genshin Impact, is only three and a half years old. Now, they continue the road to the next title in their world, with... | Read more »

Price Scanner via MacPrices.net

B&H has Apple’s 13-inch M2 MacBook Airs o...
B&H Photo has 13″ MacBook Airs with M2 CPUs and 256GB of storage in stock and on sale for up to $150 off Apple’s new MSRP, starting at only $849. Free 1-2 day delivery is available to most US... Read more
M2 Mac minis on sale for $100-$200 off MSRP,...
B&H Photo has Apple’s M2-powered Mac minis back in stock and on sale today for $100-$200 off MSRP. Free 1-2 day shipping is available for most US addresses: – Mac mini M2/256GB SSD: $499, save $... Read more
Mac Studios with M2 Max and M2 Ultra CPUs on...
B&H Photo has standard-configuration Mac Studios with Apple’s M2 Max & Ultra CPUs in stock today and on Easter sale for $200 off MSRP. Their prices are the lowest available for these models... Read more
Deal Alert! B&H Photo has Apple’s 14-inch...
B&H Photo has new Gray and Black 14″ M3, M3 Pro, and M3 Max MacBook Pros on sale for $200-$300 off MSRP, starting at only $1399. B&H offers free 1-2 day delivery to most US addresses: – 14″ 8... Read more
Department Of Justice Sets Sights On Apple In...
NEWS – The ball has finally dropped on the big Apple. The ball (metaphorically speaking) — an antitrust lawsuit filed in the U.S. on March 21 by the Department of Justice (DOJ) — came down following... Read more
New 13-inch M3 MacBook Air on sale for $999,...
Amazon has Apple’s new 13″ M3 MacBook Air on sale for $100 off MSRP for the first time, now just $999 shipped. Shipping is free: – 13″ MacBook Air (8GB RAM/256GB SSD/Space Gray): $999 $100 off MSRP... Read more
Amazon has Apple’s 9th-generation WiFi iPads...
Amazon has Apple’s 9th generation 10.2″ WiFi iPads on sale for $80-$100 off MSRP, starting only $249. Their prices are the lowest available for new iPads anywhere: – 10″ 64GB WiFi iPad (Space Gray or... Read more
Discounted 14-inch M3 MacBook Pros with 16GB...
Apple retailer Expercom has 14″ MacBook Pros with M3 CPUs and 16GB of standard memory discounted by up to $120 off Apple’s MSRP: – 14″ M3 MacBook Pro (16GB RAM/256GB SSD): $1691.06 $108 off MSRP – 14... Read more
Clearance 15-inch M2 MacBook Airs on sale for...
B&H Photo has Apple’s 15″ MacBook Airs with M2 CPUs (8GB RAM/256GB SSD) in stock today and on clearance sale for $999 in all four colors. Free 1-2 delivery is available to most US addresses.... Read more
Clearance 13-inch M1 MacBook Airs drop to onl...
B&H has Apple’s base 13″ M1 MacBook Air (Space Gray, Silver, & Gold) in stock and on clearance sale today for $300 off MSRP, only $699. Free 1-2 day shipping is available to most addresses in... Read more

Jobs Board

Medical Assistant - Surgical Oncology- *Apple...
Medical Assistant - Surgical Oncology- Apple Hill Location: WellSpan Medical Group, York, PA Schedule: Full Time Sign-On Bonus Eligible Remote/Hybrid Regular Apply Read more
Omnichannel Associate - *Apple* Blossom Mal...
Omnichannel Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
Cashier - *Apple* Blossom Mall - JCPenney (...
Cashier - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Blossom Mall Read more
Operations Associate - *Apple* Blossom Mall...
Operations Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
Business Analyst | *Apple* Pay - Banco Popu...
Business Analyst | Apple PayApply now " Apply now + Apply Now + Start applying with LinkedIn Start + Please wait Date:Mar 19, 2024 Location: San Juan-Cupey, PR Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.