TweetFollow Us on Twitter

Xcode and Code Completion

Volume Number: 19 (2003)
Issue Number: 11
Column Tag: Programming

Getting Started

Xcode and Code Completion

by Dave Mark

This month, we're going to take a look at Xcode's code completion feature. As you'll see, code completion is much like the behavior you see in your browser when you start typing a URL and the browser does its best to save you the keystrokes by filling in the closest match it can to complete the URL. But Xcode's code completion is much more than that. Follow along and you'll see what I mean.

As we've done for the past few months, we'll work with the Sketch sample project. As a reminder, the Sketch files live in /Developer/Examples/AppKit/Sketch/. Before you open Sketch, make a copy of it. We will be breaking it!

Launch Xcode and open your copy of the project Sketch.pbxproj.

Setting Code Completion Prefs

Before we dig into code completion itself, let's take a look at the code completion preferences. Select Preferences... from the Xcode menu, then click on the Navigation icon in the scrolling pane at the top of the Preferences window (Figure 1).


Figure 1. Xcode Preferences, the Navigation Pane.

Your very first course of action is to make sure the Enable Indexing checkbox is checked. The Enable Indexing checkbox tells Xcode to constantly index your project in the background as changes are made. An updated index is what makes project searches so lightning quick. Since the index is maintained in the background, the overhead is hardly noticeable. If you turn indexing off, code completion, search, and anything else that depends on the index will slow considerably. Alternatively, if you have a very large project that was never indexed, you might not want to turn on indexing if you just have a few small changes to make. No sense waiting for the index to be built if you won't be taking advantage of it. In general, I always start off with indexing turned on.

Next step, check the Enable Code Completion checkbox. Obviously, this enables code completion.

There are a series of checkboxes and radio buttons that are enabled once you enable code completion. The first of these, Automatically suggest matching option, is what does the auto-complete as you type. For example, if the constant greenColor was the only symbol in scope that started with a g, you might type g and Xcode might add a grey reenColor.

When there is more than one symbol in scope that matches the current typing, Xcode will build a list of all the matching options. This is called the option list. As you type, if there is more than one matching symbol, Xcode will display a grey ellipsis (...). Anytime you see this ellipsis, you can hit the Code Sense Complete key (see Figure 2 for the Code Sense Complete key binding - the default is F5) and the option list will popup allowing you to select from a list of matching options.

The Automatically popup option list checkbox is a bit of a puzzle to me. The sense I get is that this option controls whether the option list popup appears whenever you start typing a symbol and there is more than one match. If the checkbox is unchecked, you have to type F5 (or whatever the Code Sense Complete key binding is set to) to bring up the popup. If that is the case, then this option is broken, as it behaves the same whether this checkbox is checked or not. I've got a question in to Apple on this, but haven't heard back yet. I'm guessing this is a bug and will be fixed in the next Panther release.

The next item in the prefs dialog is the Tab key selects the current item checkbox. It allows the tab key to both bring up the option list popup and make a selection from the popup. I find this option intuitive. Play with it, both on and off, but I'd definitely leave it checked.

Next is the Contains only items matching word checkbox. If checked, the option list popup will contain only symbols that exactly match what you've typed so far. If it is unchecked, the list will contain matching items and then a few more, either before or after the matching items in the symbol list. Play with this and you'll see what I mean.

Next is a radio button set labeled Option list shows methods/functions as: with buttons for Name only and Name and arguments. This option set lets you specify whether methods/functions listed in the option list popup are listed just by name, or with arguments.

The next radio button set, Completed method/function inserted as:, lets you specify whether the selected method/function is inserted in your code as just the name or with argument placeholders.

    The rest of the Navigation prefs pane lets you determine what types of symbols are included in the editing window's function popup and whether the function popup is sorted alphabetically or by the order the symbols appear in the source file being edited.

We'll take a look at some examples that should make all these options a bit clearer. But first, we'll take a quick look at the key bindings prefs.

Changing the Key Binding

You can change most, if not all of the key bindings that ship with Xcode. Go to the Xcode menu, select Preferences..., then click on the Key Bindings icon. Now click on the Text Key Bindings tab (Figure 2.)


Figure 2. Changing the Code Sense Complete key binding.

The text key bindings are sorted into functional sets, like Text Editing, Cursor Movement, and Text Formatting, each with its own disclosure triangle. Open the Text Editing triangle. Under the c's, you'll find Code Sense Complete. In the Keys column, you should see the key binding F5. To change this to some other key, double-click on the F5. Assuming you are playing with your bindings for the first time, you'll see the dialog shown in Figure 3.


Figure 3. Making a personal copy of the Xcode key binding set.

Click Make Copy to create your own copy of the the Xcode key bindings. I named mine Dave's Bindings. Make all the changes you like to those, then use the popup menu at the top of the pane, labeled Key Binding Sets, to select Xcode Default (See Figure 4), if you ever need to go back to the original settings. You'll also find built-in key sets for BBEdit, CodeWarrior, and MPW.


Figure 4. The key binding sets that ship with Xcode.

The key binding labeled Code Sense Completion List pops up the option list, even if there is only a single item on it. More importantly, the key binding labeled Code Sense Argument Placeholder Select jumps to the next argument placeholder in your just completed code. We'll demo this is a minute.

Add a key binding for this one. Double-click in the Keys column to the right of Code Sense Argument Placeholder Select. When the edit field appears, type in your key binding. Most folks use control-slash (^/) for this one.

Taking Code Completion For A Spin

Let's take a quick look at code completion in action. I'm editing the file SKTGraphic.m in the Sketch project. Remember to make a copy of the project before you mess around with it, just so you don't break it.

I'm going to add this line of code to the project:

[self setBounds:NSMakeRect(0.0, 0.0, 1.0, 1.0)];

Since we're not concerned with compiling this code, feel free to type this line anywhere you like. Start at the beginning of a new line by typing the beginning of the line:

 [self setBounds:NSMake

Note that I typed NSM in all caps, as opposed to nsm. This is because I have the Matches using case-sensitivity checkbox checked in the Navigation prefs.

Figure 5 shows where we are at this point. Notice the ellipsis (...) that follows the NSMake, telling us that there are some matching options. If there was only one, the option would be filled in in grey.


Figure 5. The start of NSMakeRect code completion.

Now press F5 or tab to bring up the option list popup. Figure 6 shows the popup with the Contains only items matching word checkbox checked. I pressed the arrow key twice to select NSMakeRect, then pressed tab to add NSMakeRect, and its argument placeholders, in the code.


Figure 6. The option list popup for NSMake.

Here's the code at this point:


Note that each argument is marked by a placeholder between matching angle brackets and pound signs. The four arguments are x, y, w, and h. The first placeholder is selected. I want the first argument to be 0.0. I type it, then press control-slash (^/) to select the next placeholder:


I continue typing arguments and pressing ^/ until my statement is complete:


Till Next Month...

I really like this method of argument selection. It works well for me. As you've seen over the last few months, the move from Project Builder to Xcode is a quantum leap forward. I really like the attention to detail, such as the depth of preference settings on the Code Sense and Key Bindings panes. And you just know that as much as compilation performance has improved from Project Builder to Xcode, there are dramatic improvements still to come...


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 took the debugger through a few of its paces. This month's installment will focus on code completion.

 

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.