Archive for June, 2007

A nice pair of updates

Sunday, June 24th, 2007

I’ve updated my list of Favorite Feeds, which you can download from the sidebar of my blog. The list is in opml format, so you import it into feed readers such as Vienna. And speaking of Vienna, a new beta version of Vienna 2.2 has just been released. If you’re an intrepid or foolhardy type, you can download it from SourceForge. Beware: this is a pre-release version we’ve released. That’s impossible and therefore pretty scary in itself. Moreover, Vienna 2.2 hasn’t been fully tested. It’s certain to have bugs, perhaps an STD or two. We take no responsibility if your computer decides to start playing Global Thermonuclear War; in that unfortunate event, set the controls for the heart of the sun.

Working without a nib, Part 4: setAppleMenu

Sunday, June 17th, 2007

Wow, this series already has four parts. It’s entering Rocky territory, having already surpassed Rambo. If I continue much longer I’ll be typecast — (NSNib *)jeff — and no one will remember my work on Vienna or my poignant portrayal of Hamlet (in the community theater production of Guys and Dolls).

A comment by Jack Nutting inspired me to run some additional tests. As the-programmer-currently-known-as-j-o-a-r (formerly known as horse-spear) mentioned in another comment, you can use the method -[NSApplication setAppleMenu:] to set the application menu. The catch is that it’s been removed from the public API and is no longer declared in NSApplication.h. To call the method, you have to declare it yourself in a category:


@interface NSApplication (NiblessAdditions)
-(void) setAppleMenu:(NSMenu *)aMenu;
@end

You could also avoid the need for a category declaration by using [NSApp performSelector:NSSelectorFromString(@"setAppleMenu:") withObject:aMenu].

My tests revealed that AppKit does call -[NSApplication setAppleMenu:] when loading the main menu from a nib, so it appears that this method is no more (or less) fragile than the technique I discovered in Part 2. As far as I can tell, setAppleMenu: sets the title of the menu to @"Apple" and the name of the menu to @"NSAppleMenu", which is why my technique is functionally equivalent. (The method -[NSApplication setMainMenu:] sets the name of the menu to @"NSMainMenu", so my [mainMenu setValue:@"NSMainMenu" forKey:@"name"] isn’t strictly necessary.) It’s a mystery why Apple ‘disappeared’ the method. Maybe it will magically return in a later operating system, with a long beard and a dark tan.

I’m not aware of a method, hidden or otherwise, to set the recent documents menu. Thus, my technique of calling [openRecentMenu setValue:@"NSRecentDocumentsMenu" forKey:@"name"] still seems necessary. Chasing around a little chicken, though, just seems unnecessary and not very mature.

Working without a nib, Part 5: No, 3!

Sunday, June 10th, 2007

For all you desperate souls waiting in line at the Moscone Center, and you more desperate souls waiting in line at MacRumors, take heart, because there’s something even more desperate than you — NSApplicationMain(). It’s so desperate to load a nib that it’ll take the first one it can find. When your application launches, NSApplicationMain() instantiates the NSPrincipalClass from your app’s Info.plist and calls +[NSBundle loadNibNamed:owner:] with the instance as the owner. This method in turn calls +[NSBundle bundleForClass:] with your NSPrincipalClass and -[NSBundle pathForResource:ofType:] with type @"nib". If your Info.plist contains no NSMainNibFile key, then the nib name and path arguments for those methods are nil. Why in the world would your Info.plist be missing NSMainNibFile? See Part 1 of this series. If that doesn’t answer the question, see Part 2. If that doesn’t answer the question, see Part 3.

When I set the NSPrincipalClass key to my custom NSApplication subclass, the corresponding bundle for that class is my app’s main bundle, so if there’s no nib in the bundle, the app fails to launch with the error, No NSMainNibFile specified in info dictionary, exiting. However, when I leave NSPrincipalClass as NSApplication, the corresponding bundle turns out to be /System/Library/Frameworks/AppKit.framework. If you send the message -[NSBundle pathForResource:nil ofType:@"nib"] to that bundle, it returns /System/Library/Frameworks/AppKit.framework/Resources/English.lproj/NSAlertPanel.nib, which is the first nib file in the English.lproj folder. As a consequence, NSApplicationMain() attempts to load NSAlertPanel.nib and set the file’s owner to your app’s NSApplication instance. That particular nib file contains several buttons with the action buttonPressed: targeted at the file’s owner, but unlike NSAlert, which is specified as the class of the file’s owner in the nib, NSApplication doesn’t implement buttonPressed:, so you get the error, Could not connect the action buttonPressed: to target of class NSApplication. Mystery solved! And I would have gotten away with it too, if it wasn’t for those meddling kids!

There are a number of ways to handle this problem. My preferred workaround, which I’ve implemented in the revised version of the Nibless project, is to set NSPrincipalClass to JJApplication, call [[JJBundle class] poseAsClass:[NSBundle class]] in main.m, and override an NSBundle method in JJBundle.m:


+(BOOL) loadNibNamed:(NSString *)aNibNamed owner:(id)owner {
    if (!aNibNamed && owner == NSApp) {
        // We're lying here. Don't load anything.
        return YES;
    } else {
        return [super loadNibNamed:aNibNamed owner:owner];
    }
}

We now return to our regularly scheduled WWDC speculation. (I predict that everyone in the audience will get a car.) If you are attending The Keynote on Monday, remember to bring plenty of Scooby snacks. If you’re playing the home game: every time Steve says “cool”, drink!

Working without a nib, Part 2: Also Also Wik

Monday, June 4th, 2007

I apologize for the fault in the subtitle. Those responsible have been sacked. What I intended to say was that I’ve discovered the Holy Grail of Cocoa hacks: how to create a functional Cocoa application without any nib. In Part 1 of this series, I suggested that you needed a nib for the main menu of the app; some would even argue that having a nib is the essence of a Cocoa app. It turns out that I was wrong, and some (they, the unspecified straw persons) were wrong too. I apologize for any faults in my previous post. Those responsible would be sacked, but those responsible for sacking have just been sacked.

As you may recall if you have a photographic memory or nothing better to do, the main problem with getting rid of nibs is setting the application menu. I had been using a minimal nib as a workaround, but now I have a reliable, though undocumented, solution to the problem. I came upon the solution by using gdb and JJApp (along with a herring) to override initWithCoder: while the main menu is loaded from a nib. The class NSMenu has a private ivar _name, declared in /System/Library/Frameworks/AppKit.framework/Headers/NSMenu.h, that is usually nil, but a few menus — including the application menu — have a string value for the ivar. Although there are no public accessors, we can set the value anyway through the magic of key-value coding. For example, I called setValue:@"NSMainMenu" forKey:@"name" on my main menu and setValue:@"NSAppleMenu" forKey:@"name" on my application menu. This must be done before the return of -[NSApplication finishLaunching], otherwise it will have no effect. I find applicationWillFinishLaunching: to be a good place to set your main menu.

Another caveat is that the old deleting-the-nib trick doesn’t work at all if you change NSPrincipalClass in Info.plist. When I set it to my NSApplication subclass, the app refuses to launch, complaining, No NSMainNibFile specified in info dictionary, exiting. Strangely, it works fine if I leave NSPrincipalClass alone and call [[JJApplication class] poseAsClass:[NSApplication class]] in main.m. A special treat is that Cocoa automatically adds the Special Characters item to the Edit menu at runtime. Thanks, Cocoa! You can see all of this yourself by downloading my sample Xcode project, Nibless. If you use my code in your app, I may sue you, or I may kiss you. In either case, it’s a risk you’ll have to take. (It!)

Despite the fact that my solution is for the most part unsupported by official API (consult the book of armaments!), there’s good reason to think that it’s stable and should survive Leopard at least. Apple is unlikely to remove an ivar from such an important class as NSMenu. More important, the value of the ivar seems to be the way that archived menus indicate their function to Cocoa and to Interface Builder, as reflected by the “Special Menus” setting in the Inspector. Try opening keyedobjects.nib with BBEdit, and you’ll see that the file is just a plist containing definitions of the objects in the nib.

In Part 5 of this series — sorry, Part 3 — I’ll investigate the cause of the log message Could not connect the action buttonPressed: to target of class NSApplication when launching without a nib. I’ll also attempt to populate the Open Recent menu. The Clear Menu item seems to work, but for some reason I can’t get items to appear in the menu. So, um, anything that you could do to help would be very helpful.

I’d like to end this post on a personal note. Many of my legions of fans have sent emails asking for more information about me: birth date, hobbies, pet peeves, dress size, etc. I prefer not to start a cult of personality, but I’ve decided that you, the heroes, deserve something. Thus, I’m going to share one particularly juicy tidbit. My favorite color is … blue. No, yellooooooooow!