Can I write an array of UILocalNotifications to disk?

Question

I'm trying to use the following code to persist the current list of local notifications. NSArray explicitly lists the kind of objects it will work with, which implies I can not use this with an array full of UILocalNotification objects. However, UILocalNotifications does implement NSCoding, which led me to believe there must be an easy way to serialize/deserialize this list of objects. Do I need to do the encoding and file persistence myself? Also, is there a way to get more information about why the write failed?

- (NSString*)getSavedNotifsPath {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    return [documentsDirectory stringByAppendingString:@"saved_notifs.plist"];
}

- (void)prepareToHide {
UIApplication* app = [UIApplication sharedApplication];
NSArray *existingNotifications = [app scheduledLocalNotifications];
if (! [existingNotifications writeToFile:[self getSavedNotifsPath] atomically:NO] ) {
    // alert
    [self showSomething:@"write failed"];
}
}

Answer 1

First, change the code

return [documentsDirectory stringByAppendingString:@"saved_notifs.plist"];

to

return [documentsDirectory stringByAppendingPathComponent:@"saved_notifs.plist"];

stringByAppendingPathComponent: will ensure a slash (/) is included, if needed, before the file name.

NSArray can only save property list objects, which UILocalNotification is not. Instead, try using NSKeyedArchiver. For example:

- (void)prepareToHide {
   UIApplication* app = [UIApplication sharedApplication];
   NSArray *existingNotifications = [app scheduledLocalNotifications];
   NSString *path = [self getSavedNotifsPath];
   BOOL success = [NSKeyedArchiver archiveRootObject:existingNotifications toFile:path];
   if (! success ) {
      // alert
      [self showSomething:@"write failed"];
   }
}

Use NSKeyedUnarchiver to retrieve the array from the saved file.

Note: I have not actually tested this so I'm not 100% sure it will work. But give it a try and see what happens.