在didSelectRowAtIndexPath Parse.com中选择收件人时，PFUser objectId错误

Question

I'm currently building a photo messaging app where users can send photos to each other. When the photo is taken, you select recipients from a UITableView in a new View Controller.

But every time I select a person from the list and send the photo, it gets the wrong user.objectId. It seems to take the Friendship objectId which is another class named Friendship, when it should take the objectId of the user. Here's how I'm doing it:

@implementation PickRecipientsViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.recipients = [[NSMutableArray alloc] init];
    [_selectedImage setImage:_image];
    self.tableView.delegate = self;

    [self refreshFriends];
}

- (void)refreshFriends {

    [__acceptedRequests removeAllObjects];
    PFQuery *friendsQuery = [self queryForFriends];
    PFQuery *acceptedRequestQuery = [self queryForAcceptedFriendRequests];
    PFQuery *friendRequestsQuery = [self queryForRequests];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{

        // Find friends
        NSArray *objects = [friendsQuery findObjects];
        for (PFObject * obj in objects) {
            [obj[@"user1"] fetchIfNeeded];
            [obj[@"user2"] fetchIfNeeded];
        }
        _friends = [objects mutableCopy];

        // Find pending requests
        objects = [friendRequestsQuery findObjects];
        for (PFObject *obj in objects) {
            [obj[@"fromUser"] fetchIfNeeded];
        }
        __friendRequests = [objects mutableCopy];

        // Find accepted requests
        objects = [acceptedRequestQuery findObjects];
        for (PFObject *obj in objects) {
            PFUser *to = (PFUser*)[obj[@"toUser"] fetchIfNeeded];
            [obj deleteEventually];
            [__acceptedRequests addObject:to[@"username"]];
        }

        // show accepted requests
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.tableView reloadData];
            if (__acceptedRequests.count > 0) {
                NSString *friends = __acceptedRequests[0];
                for (int i = 1; i < __acceptedRequests.count; ++i) {
                    friends = [friends stringByAppendingFormat:@", %@", __acceptedRequests[i]];
                }
                friends = [friends stringByAppendingString:@" accepted your friend request"];

                UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"New Friends" message:friends delegate:self cancelButtonTitle:@"Wuhu" otherButtonTitles:nil, nil];
                alert.tag = kAlertTagAcceptedRequest;
                [alert show];
            }
        });
    });
}

- (PFQuery *)queryForAcceptedFriendRequests {
    PFUser *user = [PFUser currentUser];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"status = %@ AND (fromUser = %@ AND toUser != %@)", @"approved", user, user];
    PFQuery *acceptedRequestQuery = [PFQuery queryWithClassName:@"FriendRequest" predicate:predicate];
    return acceptedRequestQuery;
}

- (PFQuery *)queryForFriends {
    PFUser *user = [PFUser currentUser];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"user1 = %@ AND user2 != %@ OR user1 != %@ AND user2 = %@", user, user, user, user];
    PFQuery *friendsQuery = [PFQuery queryWithClassName:@"Friendship" predicate:predicate];
    return friendsQuery;
}

- (PFQuery *)queryForRequests {
    PFUser *user = [PFUser currentUser];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"status = %@ AND (toUser = %@ AND fromUser != %@)", @"pending", user, user];
    PFQuery *friendRequests = [PFQuery queryWithClassName:@"FriendRequest" predicate:predicate];
    return friendRequests;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    RecipientsTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"RecipientsTableViewCell" forIndexPath:indexPath];

    PFUser *user = [self.friends objectAtIndex:indexPath.row];

    if([self.recipients containsObject:user.objectId]){
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }else{
        cell.accessoryType = UITableViewCellAccessoryNone;
    }

    PFObject *friendRequest = [_friends objectAtIndex:indexPath.row];
    PFUser *user1 = (PFUser *)friendRequest[@"user1"];
    PFUser *user2   = (PFUser *)friendRequest[@"user2"];

    if ([user1.username isEqualToString:[PFUser currentUser].username]) {
        cell.nameL.text = user2[@"username"];

        [(PFFile*)user2[@"profilePic"] getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
            if (error) {return;}
            cell.profilePic.image = [UIImage imageWithData:data];
        }];

    } else if ([user2.username isEqualToString:[PFUser currentUser].username]) {
        cell.nameL.text = user1[@"username"];

        [(PFFile*)user1[@"profilePic"] getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
            if (error) {return;}
            cell.profilePic.image = [UIImage imageWithData:data];
        }];
    }
    return cell;
}

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

-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return _friends.count;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return 68;
}

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

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

    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
    PFUser *user = [self.friends objectAtIndex:indexPath.row];

    if (cell.accessoryType == UITableViewCellAccessoryNone){
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
        [self.recipients addObject:user.objectId];
    } else{
        cell.accessoryType = UITableViewCellAccessoryNone;
        [self.recipients removeObject:user.objectId];
    }
}

- (IBAction)sendImage {

    PFObject *message = [PFObject objectWithClassName:@"Messages"];

    [message setObject:[PFUser currentUser] forKey:@"fromUser"];
    [message setObject:[PFUser currentUser] forKey:@"toUser"];
    [message setObject:@"image" forKey:@"fileType"];

    [message setObject:self.recipients forKey:@"recipientIds"];
    [message setObject:[[PFUser currentUser] objectId] forKey:@"senderId"];

    // Image
    NSData *imageData = UIImageJPEGRepresentation(_image, 1.0);
    NSString *filename = [NSString stringWithFormat:@"image.png"];
    PFFile *imageFile = [PFFile fileWithName:filename data:imageData];
    [message setObject:imageFile forKey:@"file"];

    [message saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
        if (!error) {

            // Dismiss the controller
            [[[self presentingViewController] presentingViewController] dismissViewControllerAnimated:YES completion:nil];

        } else {
            [SVProgressHUD showErrorWithStatus:@"Oh darn! Something went wrong :("];
        }
    }];
}

@end

Answer 1

Because _friends is an array of Friendship objects and when a row is tapped you just directly get it out of the array and don't then get the appropriate user from it (like you do when you configure the cell labels).

So in tableView:didSelectRowAtIndexPath: you should have something like:

BOOL adding = NO;

if (cell.accessoryType == UITableViewCellAccessoryNone){
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
    adding = YES;
} else {
    cell.accessoryType = UITableViewCellAccessoryNone;
}

PFObject *friendRequest = [_friends objectAtIndex:indexPath.row];
PFUser *user1 = (PFUser *)friendRequest[@"user1"];
PFUser *user2 = (PFUser *)friendRequest[@"user2"];

PFUser *recipient = nil;

if ([user1.username isEqualToString:[PFUser currentUser].username]) {
    recipient = user2;
} else if ([user2.username isEqualToString:[PFUser currentUser].username]) {
    recipient = user1;
}

if (adding) {
    [self.recipients addObject:recipient.objectId];
} else {
    [self.recipients removeObject:recipient.objectId];
}