TweetFollow Us on Twitter

Checking Out Kiosk Mode Features

Volume Number: 19 (2003)
Issue Number: 12
Column Tag: Programming

Mac OS X Programming Secrets

Checking Out Kiosk Mode Features

by Scott Knaster

For about 20 years now, Apple has been telling us that modes in software are bad. It's hard to remember, especially if you're a youngster, but we used to drive software around by getting into and out of modes, restricted places that provided their own definitions for the way commands worked and actions were interpreted (kind of the way a lot of venerable UNIX text editors and command line tools work in OS X today, except this was for everybody, not just us geeks). For example, when you typed a slash into a little old spreadsheet program called VisiCalc, you went into command mode, signaling that the next character was an instruction rather than something that should appear in a cell.

But Apple in its wisdom says modes are OK in certain situations. For example, modes that emulate the real world are permitted, such as picking a type of brush in a painting program. Another kind of mode is useful when you intentionally want to limit what your users can do. This rare situation becomes reality when you consider the kiosk, a public computer that has to fend for itself when accosted by clueless newbies, hostile geeks, and keyboard-pounding toddlers.

If you're developing an application that has to run at a kiosk, Apple helps you out by providing a set of features for kiosk mode in Mac OS X. In this column, we'll take a look at how to take advantage of what OS X can do for you in kiosk mode.

Simple API

Apple put the cool new kiosk mode features into OS X 10.2, adding a little more in 10.3. You get to the features through two function calls: SetSystemUIMode and GetSystemUIMode. These calls let you effectively lock the user inside your application, preventing the hostile, curious, or ignorant from wreaking havoc. The SetSystemUIMode call is defined like this:

OSStatus SetSystemUIMode (SystemUIMode inMode,
                                        SystemUIOptions inOptions);

The inMode parameter specifies the UI mode you want, and inOptions lets you choose settings for that mode. There are five modes you can pick for your application, as shown in the following table:

System UI mode setting      Details

kUIModeNormal               The usual mode for all applications, and the mode you get if you don't 
                            make any calls to this API.
                            
kUIModeContentSuppressed    This mode prevents the system from drawing anything into the content 
                            area of the screen below the menu bar unless the user performs an action 
                            that triggers an auto-show behavior. In practice, this mode simply turns 
                            dock hiding on, which makes the dock vanish until the mouse pointer 
                            moves over it, whereupon it slides onto the screen. Note: this was 
                            broken in 10.2 and is fixed in 10.3.  
                            
kUIModeContentHidden        This mode hides the dock - technically, all system UI elements other 
                            than the menu bar - and does not show it even if the user mouses into 
                            the dock region. Note: this was also broken in 10.2 and fixed in 10.3.
                            
kUIModeAllHidden            Use this mode to hide the menu bar along with the dock, with no 
                            auto-showing feature.   
                            
kUIModeAllSuppressed        This mode was added in 10.3. Use it for hiding the dock and menu bar, 
                            but in this mode they will both auto-show if the user mouses over their 
                            content areas.  

When you call SetSystemUIMode, you also get to pass a set of options in addition to the mode you want to use. These options provide even more lock-in features for your kiosk and help you further refine the imprisonment of your rowdy user. Here's a list of the options you can choose:

System UI option                    Details

kUIOptionDisableAppleMenu           Use this option to disable all items in the Apple menu, 
                                    although despite the option's name, the appearance of the 
                                    Apple itself isn't disabled (must be a corporate logo thing). 
                                    
kUIOptionDisableProcessSwitch       This option turns off the user's ability to switch apps using 
                                    Command-Tab and Command-Shift-Tab.  
                                    
kUIOptionDisableForceQuit           If you select this option, the Force Quit item in the Apple 
                                    menu is disabled, and Command-Option-Escape doesn't do 
                                    anything. Powerful!  
                                    
kUIOptionDisableSessionTerminate    This option helps prevent the user from shutting down or 
                                    logging out. When you use it, the Restart, Shut Down, and 
                                    Log Out menu items are disabled. Also, if the user presses 
                                    the power button, the Restart/Sleep/Cancel/Shut Down alert 
                                    won't appear.  
                                    
kUIOptionAutoShowMenuBar            This option is only valid when used with kUIModeAllHidden. 
                                    Pass it to make the menu bar show itself if the user rolls 
                                    the mouse into its content region.  
                                    
kUIOptionDisableHide                This option was added in 10.3. Set it to disable the Hide item 
                                    in the application menu.  


Figure 1. You can use SetSystemUIMode to prevent users from getting access to the Force Quit and Power windows.

One of the cautions to note in using SetSystemUIMode is that the mode you set is only respected when your application is frontmost. If through magical incantation or other method the user somehow manages to bring another application to the front, the UI mode for your application is switched out along with the rest of the app.

There is a corresponding call to find out the current UI mode:

GetSystemUIMode(SystemUIMode *outMode, 
                        SystemUIOptions *outOptions);

As you can guess, calling GetSystemUIMode gets the current mode and options, in case you need to know what they are.

Depending on what your kiosk does, you might want to make the Finder go away. One good reason for this is that it prevents users from clicking on the desktop to switch out of your application. You can get rid of the Finder by sending it a kAEQuitApplication Apple event. Apple has an example to show you how to do that - it's at http://developer.apple.com/technotes/tn2002/downloads/tn2062_2.hqx .

If you just want your application to start up in one of the modified system UI modes and stay there, and you don't need to set any options, you can specify your desire in the application's property list. Just add a key named LSUIPresentationMode with type number and a value of 0, 1, 2, 3, or 4. Use 0 for normal mode, 1 for content suppressed, 2 for content hidden, 3 for all hidden, and 4 for all suppressed.

To help you view the power of the kiosk mode APIs in all their majesty, Apple provides a cool sample app, called UsingSystemUIMode, that demonstrates the various available features and tweaks. See Figure 2 for a shot of the app's screen.


Figure 2. Apple's sample application for testing kiosk mode APIs.

To get the sample app and to learn more about implementing kiosk mode in your application, see Technical Note TN2062, Guide to Creating Kiosks on Mac OS X, available at http://developer.apple.com/technotes/tn2002/tn2062.html.

No Can Do

Although the kiosk mode API is a good start toward locking up your kiosk machine, there are some things you'll want to do that you can't do yet. And just when you thought everything was perfect. Here's more information about some of those limitations:

You can't disable the eject key. If your kiosk has to run with a CD or DVD inserted, you can design the kiosk so that it's physically impossible to eject the disk.

To disable various wacky scenarios, such as taking control of the machine by booting off an external disk or booting into single-user mode by holding down Command-S, you can enable the Mac's Open Firmware password. When the Open Firmware password is enabled, the Mac will only boot from the startup disk you select in System Preferences.

You can't prevent the user from messing with the brightness keys and darkening the screen, nor can you intercept the volume keys.

One More Thing

Needless to say, locking your users in and preventing them from having basic features is not a standard design principle. In a kiosk, many of these features are necessary. In a typical app, they're practically criminal. Please use them with care, or at least a sense of humor.


Scott Knaster has been writing about Macs for as long as there have been Macs. Scott's books How To Write Macintosh Software and Macintosh Programming Secrets were required reading for Mac programmers for more than a decade. Scott wrote developer books for General Magic and worked on Mac software for Microsoft. Scott's books have been translated into Japanese and Pascal. Scott has every issue of Mad magazine, which explains a lot.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

How to get a high score in every level o...
Sky Charms is an adorable match three puzzler that provides a decent challenge thanks to its creative level design. It regularly presents something new, forcing you to think on your feet. [Read more] | Read more »
Apestorm: Full Bananas (Games)
Apestorm: Full Bananas 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: ***Launch sale – limited time only!*** Fugitive Apes have taken to the skies in search of revenge after humans have... | Read more »
How to create bigger words in Spellspire
Words have power. At least they do in Spellspire,a game about blasting out magical attacks by making words out of a jumble of letters. And it's a lot of fun. But if you want to be the best, you're going to have to think tactically when you start... | Read more »
Steel Media and DeePoon have partnered f...
Virtual reality is the next big thing, and 148Apps's publisher,Steel Media, wants to know what the hottest upcoming games are. [Read more] | Read more »
Airline Director 2 - Tycoon Game (Games...
Airline Director 2 - Tycoon Game 1.2.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.2.1 (iTunes) Description: Airline Director 2 is a management game set in the challenging field of commercial aviation. As the... | Read more »
Dog Mendonca (Games)
Dog Mendonca 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: [ Solve a criminal case beyond believe in this supernatural adventure game based on the popular graphic novel trilogy published... | Read more »
Amidakuji Knight (Games)
Amidakuji Knight 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Ghost leg rules meets RPG!Select the best path and save a princess! A long long time ago, there was a beautiful and peaceful... | Read more »
The 5 best mobile games like Game of Thr...
Everyone's favourite weekly dosage of medieval depression, Game of Thrones, is back for its sixth season. An excellent time for the bloodthirsty! [Read more] | Read more »
How to approach quests in Fallen London
Sitting at over 1.5 million words, Fallen London is filled to the brim with intriguing tales and mysterious characters. From the start, you’ll find a slew of quests ripe for the taking. [Read more] | Read more »
How to survive in LOUD on Planet X
LOUD on Planet X is a hybrid of a tower defense and rhythm game that pits famous indie acts against invading aliens. You need timing and strategy in this game in order to succeed, things can get pretty overwhelming pretty quickly. Here are some... | Read more »

Price Scanner via MacPrices.net

Aleratec Releases Mac Software Upgrade for 1...
California based Aleratec Inc., designer, developer and manufacturer of Portable Device Management (PDM) charge/sync products for mobile devices and professional-grade duplicators for hard disk... Read more
Sale! Amazon offers 27-inch iMac, 13-inch 2.9...
Amazon has the 27″ 3.2GHz 5K iMac and the 13″ 3.9GHz Retina MacBook Pro on sale for $300 off MSRP, each including free shipping, for a limited time: - 27″ 3.2GHz/1TB HD 5K iMac (model MK462LL/A): $... 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
13-inch 2.7GHz/128GB Retina MacBook Pro on sa...
Take $200 off MSRP on the price of a new 13″ 2.7GHz/128GB Retina MacBook Pro (model MF839LL/A) at Amazon. Shipping is free: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1099.99 $200 off MSRP Act now if... Read more
Apple refurbished clearance 15-inch Retina Ma...
Apple has Certified Refurbished 2014 15″ 2.2GHz Retina MacBook Pros available for $1609, $390 off original MSRP. Apple’s one-year warranty is included, and shipping is free. They have refurbished 15... Read more
27-inch 5K iMacs on sale for up to $150 off M...
B&H Photo has 27″ 5K iMacs on sale for up to $150 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2199 $100 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1849.99 $150... Read more
What Does The Refreshed 12-Inch MacBook Tell...
A lot of commentators are complaining that Apple’s update of the 12-Inch MacBook last week is a bit of a damp squib. I don’t know what they were expecting, since it would be very unlike Apple to do a... Read more
Free Wittify Keyboard Now Available On The Ap...
A team of Harvard Business School students have announced that the Wittify Keyboard, a new app utility for iOS devices, is now available on the Apple App Store. The Wittify keyboard and application... Read more
Apple Reports First Year-Over-Year Quarterly...
Apple on TUesday announced financial results for its fiscal 2016 second quarter ending March 26, 2016. The Company posted quarterly revenue of $50.6 billion and quarterly net income of $10.5 billion... Read more
13-inch 2.7GHz Retina MacBook Pros on sale fo...
Take $130-$150 off MSRP on the price of a new 13″ 2.7GHz Retina MacBook Pro at Amazon. Shipping is free: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1169 $130 off MSRP - 13″ 2.7GHz/256GB Retina MacBook... Read more

Jobs Board

*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
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
*Apple* Solutions Consultant - … (United Sta...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.