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General Discussion

Posted by Armand L.
Armand L.
71 Points

Removing Friends by Tapping on a Table View Cell

Hello.

I'm new to iOS development and I can't understand 1 thing in the following lines of code.

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    [self.tableView deselectRowAtIndexPath:indexPath animated:NO];

    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];

    PFUser *user = [self.allUsers objectAtIndex:indexPath.row];
    PFRelation *friendsRelation = [self.currentUser relationForKey:@"friendsRelation"];
    if ([self isFriend:user]) {
        cell.accessoryType = UITableViewCellAccessoryNone;

        for (PFUser *friend in self.friends) {
            if ([friend.objectId isEqualToString:user.objectId]) {
                [self.friends removeObject:friend];
                break;
            }
        }
        [friendsRelation removeObject:user];
    } else {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
        [self.friends addObject:user];
        [friendsRelation addObject:user];
    }
    [self.currentUser saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (error) {
            NSLog(@"Error %@ %@", error, [error userInfo]);
        }
    }];

}

- (BOOL)isFriend:(PFUser *)user {
    for (PFUser *friend in self.friends) {
        if ([friend.objectId isEqualToString:user.objectId]) {
            return YES;
        }
    }
    return NO;
}

Why do we need to loop twice thru the list of friends? In the video Ben Jakuben says that the user ID may change but aren't they already compared in helper method which is called by if condition?

Can't we replace:

        for (PFUser *friend in self.friends) {
            if ([friend.objectId isEqualToString:user.objectId]) {
                [self.friends removeObject:friend];
                break;
            }
        }

with this?

        [self.friends removeObject:user];

As it's in else statement.

p.s. It works.