Your First Cocoa App

The following program will open a window titled 'My First Window':

#import <Cocoa/Cocoa.h>

@interface MyWindow: NSWindow {
}

-(MyWindow*) init;

@end

@implementation MyWindow

-(MyWindow*) init {
   [super init];

   if( self ) {
      [self setTitle: @"My First Window"];
   }

   return self;
}

@end

int main( int argc, char **argv ) {
   NSAutoreleasePool *pool;
   MyWindow *window;

   /* initialise the autorelease pool */
   pool = [[NSAutoreleasePool alloc] init];

   /* initialise GUI and connect to WindowServer */
   [NSApplication sharedApplication];

   /* create the window */
   window = [[MyWindow alloc] init];

   /* set as window receiving keyboard events, and add it to the front */
   [window makeKeyAndOrderFront: NSApp];

   /* set as main window (focus) */
   [window makeMainWindow];

   /* start Cocoa event loop */
   [NSApp run];

   /* release unused objects in the pool */
   [pool release];

   return 0;
}

Ok what's going on here?

• #import is like #include, but makes sure every header file is included only once.

• Normally, @interface goes into the .h file, and the rest into the .m file.

• We created a simple window class, which sets its title upon initialisation.

• We can create stuff (windows) beforfe the event loop is started. Practical.

• The main window is the one with focus, the key window is the one receiving keyboard events.

• We need to create our own NSAutoreleasePool, since Cocoa assumes one exists. I'll explain this thing in the next section.

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