User taps on UILocalNotification: Can it pass data to the app? - iphone

Question

I am creating a local UILocalNotification and displaying it to the user as a banner. Is it possible to set it up so that when the user taps it and returns to the app, the app will receive some kind of data on the specific kind of notification it was? I want to open a specific view controller in the app. I think the best way would be to essentially send a URL to the app, or is there a way to get access to the UILocalNotification so that I can test which kind is was and do the right action?

Answer 1

To get data from the local NSUserNotification that is passed to an iOS app, all that you need to do is implement the following method: - (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification.
The problem is, this is called both when a local notification is posted when the app is in the background (i.e. when the user taps on the notification and then returns to the app), and also if the app is in the foreground at the time when the local notification fires (it is on a timer, after all). So how should one figure out if the notification was fired when the app was in the background or foreground? It's pretty simple. Here's my code:
- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {
UIApplicationState state = [application applicationState];
if (state == UIApplicationStateInactive) {
// Application was in the background when notification was delivered.
} else {
// App was running in the foreground. Perhaps
// show a UIAlertView to ask them what they want to do?
}
}
At this point you can handle the notification based on notification.userInfo, which holds a NSDictionary.

Answer 2

ust implement the NSUserNotificationCenterDelegate and define this method:
- (void)userNotificationCenter:(NSUserNotificationCenter *)center didActivateNotification:(NSUserNotification *)notification
Example:
This is what I did in a "notifier" application.
- (void) userNotificationCenter:(NSUserNotificationCenter *)center didActivateNotification:(NSUserNotification *)notification
{
NSRunAlertPanel([notification title], [notification informativeText], #"Ok", nil, nil);
}
- (void) userNotificationCenter:(NSUserNotificationCenter *)center didDeliverNotification:(NSUserNotification *)notification
{
notifications=nil;
[tableView reloadData];
[center removeDeliveredNotification: notification];
}
When the notification is activated (click by the user) I just inform the user with a panel (I could use a hud window).In this case I immediately remove the delivered notification, but this is not what happens usually.The notification could stay there some time and be removed after 1/2 hours (it depends on the application that you are developing).

Answer 3

1 - Define some class in your project to implement NSUserNoficationCenterDelegate protocol (documented here)
#interface someObject : NSObject <NSUserNotificationCenterDelegate>
{
- (void)userNotificationCenter:(NSUserNotificationCenter *)center didActivateNotification:(NSUserNotification *)notification;
}
2 - Set an instance of the object defined #1 as the delegate of default notification center.
[[NSUserNotificationCenter defaultNotificationCenter] setDelegate: someObject];
Now you will get called on didActivateNotification any time the user taps/clicks on the notification. You will have the original notification you created. So any information that you need should be available to you.
If you want/need special information (other than notification title, message, etc) you will probably need to set additional application specific information in your notification before you schedule it to be sent. For example:
NSUserNotification* notification = [[NSUserNotification alloc] init];
NSDictionary* specialInformation = [NSDictionary dictionaryWithObjectsAndKeys: #"specialValue", #"specialKey", nil];
[notification setUserInfo:specialInformation];