Check a condition in the background every ten seconds and send notification

I'm working on an app for Mac OS X. My app checks something every ten seconds, and if the condition is true, the app sends a Growl notification.

I've already coded the Growl notifications and the checking. I just need to know how to make this checking repeat itself every ten seconds, and each time send a notification if true, all in the background.

Please write the exact code, as I am very new to Objective-C. Thank you :D

-------------------------------EDIT------------------------------------

Currently i'm using this:

//  MyApp_AppDelegate.m

#import "MyApp_AppDelegate.h"

@implementation MyApp_AppDelegate

- (void)awakeFromNib {
    return;
}


-(void)applicationDidFinishLaunching:(NSNotification*)aNotification {

    // grwol:
    NSBundle *myBundle = [NSBundle bundleForClass:[MyApp_AppDelegate class]];
    NSString *growlPath = [[myBundle privateFrameworksPath] stringByAppendingPathComponent:@"Growl-WithInstaller.framework"];
    NSBundle *growlBundle = [NSBundle bundleWithPath:growlPath];

    #include <unistd.h>

    int x = 0;
    int l = 10; // time/repeats
    int t = 10; //seconds
    while ( x <= l ) {

        // more code here only to determine sendgrowl value...

        if(sendgrowl) {
            if (growlBundle && [growlBundle load]) {
                // more code to sends growl
            } else {
                NSLog(@"ERROR: Could not load Growl.framework");
            }
        }

        // do other stuff that doesn't matter...

        // wait:
        sleep(t);

        x++;
    }
}

/* Dealloc method */
- (void) dealloc { 
    [super dealloc]; 
}

@en开发者_JAVA百科d

The exact code that you are looking for can be found here: Time Programming Topics

-(void) sendGrowl { } // your growl method

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:10 target:self 
                  selector:@selector(sendGrowl) userInfo:nil repeats:YES]; 

When you are done with the timer call [timer invalidate]. Paste to XCode and alt+click it to read the docs.

To schedule a timer to run every 10 seconds, you need this:

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval: 10.0
                                                  target: someObject 
                                                selector: @selector(fire:)
                                                userInfo: someParameter
                                                 repeats: YES];

That will create a timer and put it on the run loop such that it fires every 10 seconds. When it fires, it is equivalent to the following method invocation:

[someObject fire: someParameter];

You are allowed to pass nil as someParameter in which case your selector need not take a parameter i.e. it could be -fire rather than -fire:.

To stop a timer, simply send it the invalidate message.

[timer invalidate];

Timers require a run loop to work. This is fine if you run it on the main thread of your application since the main thread already has a run loop (it's what handles UI events and passes them off to your actions). If you want the timer to fire on a different thread, you have to create and run a run loop on that different thread. This is a bit more advanced, so given you are new to Objective-C avoid it for now.

Edit

Having seen what you are trying to do, the first bit of code to schedule the timer needs to replace that entire while loop. The -fire method would look something like:

-fire
{
    // code here only to determine sendgrowl value...

    if(sendgrowl) 
    {
        if (growlBundle && [growlBundle load]) 
        {
            // more code to sends growl
        }
        else 
        {
            NSLog(@"ERROR: Could not load Growl.framework");
        }
    }
    // do other stuff that doesn't matter...
}