pull notification locally on jailbroken device

Question

Since the iOS framework doesn\'t allow local notifications to execute code before they are posted, I\'m looking for a way to achieve it on a jailbroken device.

Answer 1

... Or post the notification any other way?

Yes. You can make this work with a background (launch) daemon that triggers a notification (not necessarily a UILocalNotification). When the notification shows the user an alert, your daemon can then decide to open a normal UI application (or not).

Build a Launch Daemon.

This is the best tutorial I've found. The launch daemon starts when the phone boots, and runs all the time as a non-graphical background process. From there, you can schedule your check for updates. (I have a HelloDaemon class which does all its work in the run: method):

int main(int argc, char *argv[]) {
    @autoreleasepool {
        HelloDaemon* daemon = [[HelloDaemon alloc] init];
        
        // start a timer so that the process does not exit.
        NSTimer* timer = [[NSTimer alloc] initWithFireDate: [NSDate date]
                                                  interval: 1.0
                                                    target: daemon
                                                  selector: @selector(run:)
                                                  userInfo: nil
                                                   repeats: NO];
        
        NSRunLoop* runLoop = [NSRunLoop currentRunLoop];
        [runLoop addTimer: timer forMode: NSDefaultRunLoopMode];
        [runLoop run];
    }    
    return 0;
}

Daemons can use NSTimer normally, so schedule another timer (within run:) to check for updates to download whenever you want.

Notify User from Daemon

If the daemon decides that the user should be notified, then you can either:

1) open the full UI application.

#include 
#define SBSERVPATH "/System/Library/PrivateFrameworks/SpringBoardServices.framework/SpringBoardServices"

-(void) openApp {
  
    // the SpringboardServices.framework private framework can launch apps,
    //  so we open it dynamically and find SBSLaunchApplicationWithIdentifier()
    void* sbServices = dlopen(SBSERVPATH, RTLD_LAZY);
    int (*SBSLaunchApplicationWithIdentifier)(CFStringRef identifier, Boolean suspended) = dlsym(sbServices, "SBSLaunchApplicationWithIdentifier");
    int result = SBSLaunchApplicationWithIdentifier(CFSTR("com.mycompany.AppName"), false);
    dlclose(sbServices);
}

This code requires the com.apple.springboard.launchapplications entitlement for your daemon to use it successfully. See here for adding an entitlement. You'd need an entitlements.xml file for your daemon executable, like this:

    
        com.apple.springboard.launchapplications
        
    

2) show a simple alert window from your daemon, notifying the user of the event, and prompting them to open the UI app

#include "CFUserNotification.h"

-(void) showAlert {
  
    NSMutableDictionary* dict = [NSMutableDictionary dictionary];
    [dict setObject: @"Alert!" forKey: (__bridge NSString*)kCFUserNotificationAlertHeaderKey];
    [dict setObject: @"Updates Ready!" forKey: (__bridge NSString*)kCFUserNotificationAlertMessageKey];
    [dict setObject: @"View" forKey:(__bridge NSString*)kCFUserNotificationDefaultButtonTitleKey];
    [dict setObject: @"Cancel" forKey:(__bridge NSString*)kCFUserNotificationAlternateButtonTitleKey];
    
    SInt32 error = 0;
    CFUserNotificationRef alert =
    CFUserNotificationCreate(NULL, 0, kCFUserNotificationPlainAlertLevel, &error, (__bridge CFDictionaryRef)dict);
    
    CFOptionFlags response;
    // we block, waiting for a response, for up to 10 seconds
    if((error) || (CFUserNotificationReceiveResponse(alert, 10, &response))) {
        NSLog(@"alert error or no user response after 10 seconds");
    } else if((response & 0x3) == kCFUserNotificationAlternateResponse) {
        // user clicked on Cancel ... just do nothing
        NSLog(@"cancel");
    } else if((response & 0x3) == kCFUserNotificationDefaultResponse) {
        // user clicked on View ... so, open the UI App
        NSLog(@"view");
        [self openApp];
    }
    CFRelease(alert);
}

You'll need a CFUserNotification.h header to use the code the way I did above. You can find one by googling, or see one here. This older wiki document also shows some good information for using CFUserNotification from iOS apps.

The answer I linked to from KennyTM above also shows how you can make your alert popup show, even if the device is locked.