TweetFollow Us on Twitter

Enhancing Your Application with NSStatusItem

Volume Number: 24 (2008)
Issue Number: 07
Column Tag: Application Development

Enhancing Your Application with NSStatusItem

How to utilize the NSStatusItem API to add functionalitys

by Marcus S. Zarra

Introduction

The user interface is arguably the hardest part of any application. This is especially true on OS X because we, as users, demand more of the developers of our applications. If the developer adds too many features and UI elements, then the application feels too busy or complicated. However if too few features are added then application is too primitive or simple.

Fortunately there are some choices. An application that would be considered too simple for the Dock might be perfect on the Dashboard or on the Menu Bar. Likewise, an application that is too busy to be a Dashboard widget might very well be perfectly at home in the Dock. But what if you are in the grey area between the Dock and the Menu Bar? While the design choices between these options ischoices between these options are beyond the scope of this article, I will present how to add a Menu Bar item – also known as a menu extra, menu item or menulet – to to your application and how to control it.

Menu Bar Items: Two Different Beasts

There are two different kinds of objects that can be placed on the menu bar in the upper right corner. First there is the kind that only Apple is allowedallows. The API is private and at the time of this article, third party developers are discouraged from using them.

The second kind that developers are encouraged to use is the NSStatusItem API. The NSStatusItem behaves decidedly different than the internal API that Apple uses. First, NSStatusItem objects cannot be dragged around the menu bar; second they cannot be removed from the menu bar with the mouse; and lastly, they are more "sluggish" than the Apple internal items when another item on the bar is moved or removed.

However, they are still an extremely useful UI element that can be utilized to great effect. The basic concept behind them is that they are a menu with an icon. In that respect, their behavior is very similar to NSMenuItem objects.

Building an NSStatusItem

While it is possible to build an NSStatusItem 100% in code, I prefer to use Interface Builder wherever whenever possible. This makes localizations easier and reduces the amount of code I need to maintain. Therefore, the first step to building an NSStatusItem is to build its menu in Interface Builder.

Building the Menu

To add a new menu to the project, I open the MainMenu.xib file and drag in a new NSMenu object (See Image 1). I normally rename the new menu to "Status Menu" or something similar to keep it clear which menu is which.


Image 1: Drag a new NSMenu into the nib

When an NSMenu is first added it contains three menu items. These items can be added to, removed from and changed as needed. For this example, I have changed the menu so that it has four items: Status, a separator, About and Quit. When I am done the menu looks like Image 2.


Image 2: The finished menu in IB

Now that the menu itself is complete it is time to write some code. For this example, the AppDelegate of my project will be responsible for the NSStatusItem. First, the header:

AppDelegate.h
#import <Cocoa/Cocoa.h>
@interface AppDelegate : NSObject {
   NSStatusItem *myStatusItem;
   IBOutlet NSMenu *myStatusMenu;
   IBOutlet NSMenuItem *myMenuStatusItem;
}
@end

Since both the about menu item and the quit menu item can be handled outside of the AppDelegate in this example, I have not added IBAction methods for them. Once the header has been written, it is time to go back to Interface Builder and link the references as shown in Image 3.

As for the About and Quit menus, they are linked to the Application object as follows:

About -> NSApplication -orderFrontStandardAboutPanel:
Quit -> NSApplication -terminate:

Once all of the linking is complete, I am done withwith the work with Interface Builder is complete;. tTime to move on to the AppDelegate. In this situation I prefer to initialize the NSStatusItem in the applicationDidFinishLaunching: method so that it appears as soon as the application is ready to start receiving events. Depending on an applications particular situation the initialization code can be placed in other locations.

AppDelegate.m
#import "AppDelegate.h"
@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification*)notification
{
   myStatusItem = [[[NSStatusBar systemStatusBar] statusItemWithLength:NSSquareStatusItemLength] retain];
   
   NSImage *statusImage = [NSImage imageNamed:@"TheZ.tiff"];
   [myStatusItem setImage:statusImage];
   [myStatusItem setHighlightMode:YES];
   
   [myStatusItem setMenu:myStatusMenu];
   
   [myMenuStatusItem setTitle:NSLocalizedString(@"Special Status", @"status menu item text")];
}
@end

The first thing to notice in this code block is that NSStatusItem objects are not initialized directly. Rather, they are requested from an NSStatusBar object. The NSStatusBar object has a class level method that returns the system status bar from which I one can request a NSStatusItem.

Once I have my newthe NSStatusItem request is complete, it is possibleI am able to set its image, highlight mode and menu. The image is the image that is displayed on the Menu Bar and is has a 16x16 resolutionimage. The highlight mode determines whether or not the image is highlighted when clicked. The default is "NO", which is not appropriate when a menu is attached so I have set it to YES in the sample code. The last call to myStatusItem passes it the menu that isI constructed and referenced in Interface Builder. This will be the menu that the NSStatusItem displays when it is clicked.

The last line of the applicationDidFinishLaunching: method is a call to the status menu item that isI referenced from Interface Builder. This call changes the text of that menu item. Note that the sample code doesI have not disabled this menu. Since it does not have a target or action it will be displayed grayed out already so there is no need to disable it.

Controlling The Menu

In various situations it is appropriate to make changes to the NSStatusItem or one of its menu items. In this example, I have intentionally linked the *myStatusMenuItem ivar to one of the NSMenuItem objects on the menu so that it can be changed during the life of the program. To illustrate this change, I added a button to the main window that when clicked would change this menu item:


Image 3: Linking the AppDelegate to the Menu

AppDelegate.h
-(IBAction)changeMenu:(id)sender;
AppDelegate.m
-(IBAction)changeMenu:(id)sender;
{
  [myMenuStatusItem setTitle:NSLocalizedString(@"Changed Status", @"statuc menu item changed text")];
}

With this addition to the application, the status menu item will change to "Changed Status".

It is also possible to change the image that is displayed on the Menu Bar

AppDelegate.h
-(IBAction)purpleZ:(id)sender;
-(IBAction)blackZ:(id)sender;
AppDelegate.m
-(IBAction)purpleZ:(id)sender;
{
   [myStatusItem setImage:[NSImage imageNamed:@"ThePurpleZ.tiff"]];
}
-(IBAction)blackZ:(id)sender;
{
   [myStatusItem setImage:[NSImage imageNamed:@"TheZ.tiff"]];
}

In the example application, I added these actions are added to the Format menu rather than buttons on the main window.

Lastly, if it is desired to have the NSStatusItem as an option rather than a requirement in the application, it is possible to remove the menu item from the bar:

AppDelegate.h
-(IBAction)removeStatusItem:(id)sender;
-(IBAction)addStatusItem:(id)sender;
AppDelegate.m
-(IBAction)removeStatusItem:(id)sender;
{
   [[NSStatusBar systemStatusBar] removeStatusItem:myStatusItem];
   myStatusItem = nil;
}
-(IBAction)addStatusItem:(id)sender;
{
   if (myStatusItem) return;
   myStatusItem = [[[NSStatusBar systemStatusBar] statusItemWithLength:NSVariableStatusItemLength] retain];
   
   [myStatusItem setImage:[NSImage imageNamed:@"TheZ.tiff"]];
   [myStatusItem setHighlightMode:YES];
   [myStatusItem setMenu:myStatusMenu];
   
   [myMenuStatusItem setTitle:NSLocalizedString(@"Special Status", @"status menu item text")];
}
-(BOOL)validateMenuItem:(NSMenuItem*)item
{
   if ([item action] == @selector(removeStatusItem:)) {
      return (myStatusItem != nil);
   }
   if ([item action] == @selector(addStatusItem:)) {
      return (myStatusItem == nil);
   }
   return YES;
}

The code to remove the status item is very simple. Just one call to NSStatusBar -removeStatusItem: and it is gone. Since there is no way to add the existing item back to the bar it is prudent to set the ivar to nil at this time.

To add the NSStatusItem back to the bar, the example I simply copiesd the code from the applicationDidFinishLaunching: method. Ideally this should be abstracted so that the code is not duplicated.

Lastly, I addedthere is a -validateMenuItem: method to make sure that only one status item is ever added and just as importantly, that the application is not trying to remove a non-existent item I do not try to remove a non-existent item.

Now, with the addition of a checkbox in the preferences linked to NSUserDefaults, it is trivial to add a user preference on whether or not to show the status item. OneI could then add logic to the applicationDidFinishLaunching: method to decide whether or not a NSStatusItem needs to be initialized based on the NSUserDefault.

Conclusion

That is all there is to the NSStatusItem API. Hopefully, one day, Apple will allow third party developers to utilize their internal status items so that we can legitimately produce menu bar items that are feature comparable to the system items. Until then, NSStatusItem is a solid API that we can utilize.

As a parting comment, if I wanted my entire application to run as a menu bar item (without a Dock icon ala Twitterific), that only requires one small addition to the Info.plist:

Info.plist
<key>LSUIElement</key>
<string>1</string>

And the application will not bounce in the dock at all. I do not recommend that for this example application as it is not designed to run in that manner but there are plenty of applications that this is perfectly suited for.

NOTE: This change cannot be made to an application on the fly. So if you wanted to make the Dock icon optional also it would require an application restart and probably some trickery with the Finder as the Finder does tend to "cache" the Info.plist file for applications.


Marcus S. Zarra is the owner of Zarra Studios, based out of Colorado Springs, Colorado. He has been developing Cocoa software since 2003, Java software since 1996, and has been in the industry since 1985. Currently Marcus is producing software for OS X. In addition to writing software, he assists other developers by blogging about development and supplying code samples.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Gordon Ramsay DASH: Guide to upgrading a...
If we've learned anything about celebrity chef Gordon Ramsay over the years, it's that you don't want him angry and breathing down your neck. He's not above calling you out on TV, making a mockery of your efforts in the kitchen in front of... | Read more »
Galaxy of Trian (Games)
Galaxy of Trian 1.1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1.0 (iTunes) Description: Galaxy of Trian is an exciting, fast paced digital board game based on the highly acclaimed tabletop title. | Read more »
Dead In Bermuda (Games)
Dead In Bermuda 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
The Little Fox (Games)
The Little Fox 1.0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1 (iTunes) Description: The Little Fox is an alternative perspective on the world-renowned ‘fairy tale for adults', The Little Prince by Antoine de... | Read more »
5 popular free fertility apps
There was a good article this week in The Independent about how more women are using fertility appsas a de facto form of contraception. It's apparently not working too well, leading to numerous unwanted pregnancies. [Read more] | Read more »
How to get more cars in CSR Racing 2
NaturalMotion and Zynga brought a lot of real life cars to the table for CSR Racing 2. From souped up everyday rides made by Nissan and Hyundai to supercars produced by the likes of McLaren and Pagani, there really is something for everyone. [... | Read more »
Crypt of the NecroDancer Pocket Edition...
Crypt of the NecroDancer Pocket Edition 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Crypt of the NecroDancer is an award winning hardcore roguelike rhythm game. Move to the music and... | Read more »
Gear-grinding puzzle title Inner Circle...
If you saw our post earlier this month announcing the imminent release of ZPlay’s new creation, Inner Circle, you’ll be happy to know that it’s now available on the App Store. Established in 2010, developer and publisher ZPlay have taken the... | Read more »
CSR Racing 2: Your guide to what's...
CSR Racing 2, or CSR2, as it likes to call itself, has finally arrived. The follow-up to the immensely popular drag racing game CSR Racing is the first release from NaturalMotion since the studio's acquisition by Zynga in early 2014. [Read more] | Read more »
Nanuleu (Games)
Nanuleu 1.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1 (iTunes) Description: Nanuleu is a strategy game where you take control of ancient magical trees that protect the land from an invading dark force. A... | Read more »

Price Scanner via MacPrices.net

July 4th sale: $100 off 13-inch MacBook Airs
Amazon has 13″ MacBook Airs on sale for $100 off MSRP for a limited time. Shipping is free: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $899.99 $100 off MSRP - 13″ 1.6GHz/256GB MacBook Air (sku... Read more
Swiftpoint Launches Advanced Pivot, Tilt And...
Christchurch, New Zealand based Swiftpoint has announced the launch of its new generation computer mouse, The Z, on the crowdfunding website kickstarter.com. The company’s previous device, the... Read more
Clearance 12-inch Retina MacBooks, Apple refu...
Apple has Certified Refurbished 2015 12″ Retina MacBooks available starting at $929. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more
12-inch MacBooks available with free bundles...
Adorama has 12″ Retina MacBooks available including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB Adapter, free 4-Port USB Hub, and... Read more
Das Keyboard Unveils First Cloud-Connected Ke...
Austin, Texas based Das Keyboard has unveiled the newest addition to its family of high-performance mechanical keyboards with the introduction of the Das Keyboard 5Q on Kickstarter. Built with... Read more
13-inch 2.7GHz Retina MacBook Pros on sale fo...
Adorama has 13″ 2.7GHz Retina MacBook Pros on sale for up to $130 off MSRP. Shipping is free, and Adorama charges NY & NJ sales tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1169 $130 off -... Read more
New App Reminds Us to Put Down Our Phones and...
Mode, a new smartphone app that makes us more mindful of how we use our devices, debuts in the app stores today. The Mode app tracks time spent in different modes of day-to-day life without... Read more
ZuumSpeed Personalized Speedometer + HUD For...
RMKapps has announced the release and immediate availability of ZuumSpeed 1.0, its personalized speedometer plus heads up display for iOS devices. ZuumSpeed gives users over 18 custom fonts available... 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
9-inch 128GB Silver iPad Pro on sale for $50...
B&H Photo has the 9.7″ 128GB Silver Apple iPad Pro on sale for $699 including free shipping plus NY tax only. Their price is $50 off MSRP. 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
*Apple* iPhone 6s and New Products Tester Ne...
…we therefore look forward to put out products to quality test for durability. Apple leads the digital music revolution with its iPods and iTunes online store, Read more
*Apple* Retail - Multiple Positions, Fort Wo...
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
*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
*Apple* iPhone 6s and New Products Tester Ne...
…we therefore look forward to put out products to quality test for durability. Apple leads the digital music revolution with its iPods and iTunes online store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.