Checking for Existing Friend Requests in Parse - objective-c

Question

I am creating my own friend network using parse and want to check to see if a friend request has been sent from one user to another. However, it seems that when I query my parse database it takes some time to receive the information and therefore acts as if a friend request had never been made between two users even though the relationship exists already.
//This is the method to test to see if the request has already been sent
-(int) testForFriendRequestBetween: (NSString *) ID1 and: (NSString *) ID2
{
NSString *user1 = ID1;
NSString *user2 = ID2;
PFQuery *query1 = [PFQuery queryWithClassName:#"friendRequest"];
[query1 whereKey:#"requestFrom" equalTo:user1];
[query1 whereKey:#"requestTo" equalTo:user2];
[query1 findObjectsInBackgroundWithBlock:^(NSArray *objects1, NSError *error) {
if (error)
{
a = 0;
NSLog(#"Error with query");
}
else
{
a = objects1.count;
NSLog(#"%i", a);
}}];
return a;
}
//This is where the user types in an email address to search for a friend and I test to see if request already exists
- (IBAction)sendRequest:(id)sender
{
PFUser *currentUser = [PFUser currentUser];
NSString *myID = currentUser.objectId;
//Look in email column and search whatever was typed into the texfield
PFQuery *query = [PFQuery queryWithClassName:#"_User"];
[query whereKey:#"email" equalTo: _typeEmail.text];
[query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error)
{
//If the user was found
if (!error)
{
//Create a string that reads the unique ID
NSString *friendID = object.objectId;
//Test to see if request already exists
int test1 = [self testForFriendRequestBetween:myID and:friendID];
int test2 = [self testForFriendRequestBetween:friendID and:myID];
if(test1+test2 == 0)
{
NSLog(#"%i", test1+test2);
//Save request to new row
PFObject *request = [PFObject objectWithClassName:#"friendRequest"];
request[#"requestFrom"] = myID;
request[#"requestTo"] = friendID;
request[#"status"] = #"pending";
[request saveInBackground];
//Update label
_requestLabel.text = #"Friend Request Sent";
} else
{
_requestLabel.text = #"Request Already Sent";
}
}
//If user was not found
else
{
//Update label
_requestLabel.text = #"Friend Is Not Registered";
}
}
];
}
The output of this in the console is:
2014-07-07 13:14:25.559 SignIn[11363:70b] 0
2014-07-07 13:14:25.667 SignIn[11363:70b] 14
2014-07-07 13:14:25.730 SignIn[11363:70b] 2
This means that it is first reporting that test1 + test2 = 0. But then it runs the first method and says that the value of test1 is 14 and the value of test2 is 2! Any help would be much appreciated.

Answer 1

Your implementation of testForFriendRequestBetween has a serious bug. You return a value that does not have a valid value. If you make an asynchronous request, like you do with findObjectsInBackgroundWithBlock:, you can't return the result of that call synchronously (i.e. by using return a. Instead, your method should have a callback block with a parameter that contains the data you receive from the query. You call that callback inside the query completion block.
Here's a simple example based on your code. As you see, all the results are processed in the callback blocks. This is the only correct way when you get the data using async calls.
- (void)testForFriendRequestBetween:(NSString *)ID1 and:(NSString *)ID2 callback:(void (^)(NSArray *results))completion {
// configure the query object, etc.
[query1 findObjectsInBackgroundWithBlock:^(NSArray *objects1, NSError *error) {
if(!error) {
// now you can send the query results back to the caller!
callback(objects1);
}
}
}
- (IBAction)sendRequest:(id)sender
{
// set up query, etc.
[query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error)
{
//If the user was found
if (!error)
{
[self testForFriendRequestBetween:myID and:friendID callback:^(NSArray *results) {
if(results.count == 0) {
// do stuff
}
}];
}
}
}