Monitoring Screensaver Events in OSX

Question

I want to monitor screensaver and lockscreen events on an OSX box. As a first pass, I\'m fine with them just printing to the console.

Following the advice of another\'s

Answer 1

Edit: further testing showed that com.apple.screensaver.didlaunch is also available, the code here is tested on 10.6.8 and 10.8.4

Your code will work if you remove [[NSRunLoop currentRunLoop] run]; and initialize ScreenSaverMonitor from a Cocoa application's applicationDidFinishLaunching: method. ( Just create a new Cocoa application project in XCode and add your code where appropriate ).

ScreenSaverMonitor.h

#import 

@interface ScreenSaverMonitor : NSObject
-(id) init;
-(void) receive: (NSNotification*) notification;

@end

ScreenSaverMonitor.m

#import "ScreenSaverMonitor.h"
#import 
#import 
#import 
#import 

@implementation ScreenSaverMonitor
-(id) init {
    NSDistributedNotificationCenter * center
    = [NSDistributedNotificationCenter defaultCenter];

    [center addObserver: self
               selector:    @selector(receive:)
                   name:        @"com.apple.screensaver.didlaunch"
                 object:      nil
     ];

    [center addObserver: self
               selector:    @selector(receive:)
                   name:        @"com.apple.screensaver.didstart"
                 object:      nil
     ];
    [center addObserver: self
               selector:    @selector(receive:)
                   name:        @"com.apple.screensaver.didstop"
                 object:      nil
     ];
    [center addObserver: self
               selector:    @selector(receive:)
                   name:        @"com.apple.screenIsLocked"
                 object:      nil
     ];
    [center addObserver: self
               selector:    @selector(receive:)
                   name:        @"com.apple.screenIsUnlocked"
                 object:      nil
     ];
    return self;
}
-(void) receive: (NSNotification*) notification {
    printf("%s\n", [[notification name] UTF8String] );
}

@end

AppDelegate.h

#import 
#import "ScreenSaverMonitor.h"

@interface AppDelegate : NSObject 

@property (assign) IBOutlet NSWindow *window;
@property (retain) ScreenSaverMonitor *monitor;
@end

AppDelegate.m

#import "AppDelegate.h"
#import "ScreenSaverMonitor.h"

@implementation AppDelegate
@synthesize monitor;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Insert code here to initialize your application
    self.monitor = [[ScreenSaverMonitor alloc] init];

}

@end

main.m

#import 

int main(int argc, char *argv[])
{
    return NSApplicationMain(argc, (const char **)argv);
}