Parse.com向朋友推送通知

Question

In my app I am using a PFRelation so a user can add friends.

I want the currentUser to tap a UIButton and it sends a push notification to their friends.

Right now I have it set up using their example and the push goes to every user.

Is there a specific query search? Or something else?

// Create our Installation query
PFQuery *pushQuery = [PFInstallation query];
[pushQuery whereKey:@"deviceType" equalTo:@"ios"];

// Send push notification to query
[PFPush sendPushMessageToQueryInBackground:pushQuery
                           withMessage:@"Hello World!"];

EDIT:

Here is what I have tried to get the objects, but nothing is returned:

PFQuery * theQuery = [PFUser query];
[theQuery whereKeyExists:@"friendsRelation"];
[theQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {

    if (error)
    {
        NSLog(@"Error: %@ %@", error, [error userInfo]);
    }
    else
    {
        self.friends = objects;
    }
}];

EDIT TWO:

I know can bring up a list of the currentUser's friends.

Next step I can not figure out, how to send the push notification to the NSArray of friends.

    PFRelation *rel = [[PFUser currentUser] relationForKey:@"friendsRelation"];
    [[rel query] findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (error)
        {
            NSLog(@"Error: %@ %@", error, [error userInfo]);
        }
        else
        {
            self.friends = objects;
            NSLog(@"objects are: %@", [self.friends valueForKey:@"username"]);
        }
    }];

EDIT THREE:

Here's what I have setup in my App Delegate:

- (void)application:(UIApplication *)application
didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken
{
    PFUser *currentUser = [PFUser currentUser];

    if (currentUser)
    {
        // Store the deviceToken in the current Installation and save it to Parse.
        PFInstallation *currentInstallation = [PFInstallation currentInstallation];
        [currentInstallation setDeviceTokenFromData:deviceToken];
        [currentInstallation setObject:[PFUser currentUser].objectId forKey:@"owner"];
        [currentInstallation saveInBackground];
    }
}

Answer 1

Now you will want to query the installation table for all installations where the owner is a user in the array of friends.

Here is some code, I'm on my iphone so it may not be exactly correct:

// Create our Installation query
PFQuery *pushQuery = [PFInstallation query];
[pushQuery whereKey:@"owner" containedIn:self.friends];

// Send push notification to query
[PFPush sendPushMessageToQueryInBackground:pushQuery
                           withMessage:@"Hello World!"];

If you don't have an owner column in your installation table, there is something in the parse docs about adding a user pointer to an installation.