Add unique object to PFquery that is user - ios

Question

I am trying to add a list people who follow a user to the column titled "Followers" under the user, which is retrieved from objectatindex of a sender tag.
Here is the code:
-(void)followButton:(id)sender {
UIButton *senderButton = (UIButton *)sender;
NSLog(#"current Row=%ld",(long)senderButton.tag);
PFObject *object = [self.objects objectAtIndex:senderButton.tag];
if (![[object objectForKey:#"followers"]containsObject:[PFUser currentUser].objectId]) {
[[PFUser currentUser] addUniqueObject:object.objectId forKey:#"following"];
[[PFUser currentUser] saveInBackground];
PFUser *otherUser = [self.objects objectAtIndex:senderButton.tag];
NSLog(#"Followed %#", otherUser);
[otherUser addUniqueObject:[PFUser currentUser].objectId forKey:#"followers"];
[otherUser saveInBackground];
// NSLog(#"Followed %#", object);
} else {
[[PFUser currentUser] removeObject:object.objectId forKey:#"following"];
[[PFUser currentUser] saveInBackground];
PFUser *otherUser = [self.objects objectAtIndex:senderButton.tag];
[otherUser removeObject:[PFUser currentUser].objectId forKey:#"followers"];
[otherUser saveInBackground];
}
[self.tableView reloadData];
}
For some reason, the code above only adds to the array of "Following" of the current user. When re-clicked, the object is to be removed but nothing happens. Additionally, the code
PFUser *otherUser = [self.objects objectAtIndex:senderButton.tag];
[otherUser removeObject:[PFUser currentUser].objectId forKey:#"followers"];
[otherUser saveInBackground];
does absolutely nothing meanwhile it supposed to do the work of add to the "Followers" array of the user at the selected row. What am I doing wrong? The goal's to get a working following/followers action. I'm using PFQueryTableViewController!

Answer 1

You can't modify other user's objects from the client. You can only modify the current user. The way to modify users that are the current user is to use the master key in the cloud code by using Parse.Cloud.useMasterKey();
https://parse.com/questions/how-can-i-allow-a-user-to-edit-another-user
So create a function in the cloud code by passing the username of the "otherUser" and the objectId that you want to remove
Parse.Cloud.define("RemoveFollower", function(request, response){
var username = request.params.username;
var id_to_remove = request.params.objectId_passed;
var query = new Parse.Query(Parse.User);
query.equalTo("username", username);
query.find({
success: function(results){
var u = results[0];
//u modify the user u however you like...
u.save();
response.success("Success");
},
error: function(){
response.error("Error");
}
});