CODEWITHSUNDEEP
iosobjective-cuitableview
user3105870
user3105870

Reputation: 95

reloadData not calling cellForRowAtIndexPath

My project uses a Split View Controller containing a table view with a list of class periods and a main view detailing the class periods. When the app first loads up, there are no entries in the table view and the main view shows a login screen. When the user logs in, the table view is supposed to reload with text containing the title of each class period. I am unable to get the data to reload correctly.

When the login button is pressed a message is sent to the App delegate...

- (IBAction)login:(id)sender
{
    if([self.appDelegate validateUsername:self.usernameField.text validatePassword:self.passwordField.text]) {
        NSLog(@"Login Successful!");
        [self performSegueWithIdentifier:@"loginSegue" sender:sender];
    }else {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Login" message:@"Unsuccessful :(" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alert show];
    }
}

...which checks to see if the username information is valid. If it is, a segue in the main view is performed. The validate username method looks like this:

- (BOOL)validateUsername:(NSString *)username validatePassword:(NSString *)password
{
    // The "username isEqualToString" is placeholder.  This message will request a login and proceed if the login is successful
    if([username isEqualToString:@"username"] && [password isEqualToString:@"password"]) {
        self.student = [SCHStudent newStudentWithName:@"Random Student"];
        [self loadData];
        return YES;
    }else {
        return NO;
    }
}

[self loadData] loads an array of class periods to show in the table view:

- (void)loadData
{
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher1" periodNumber:1]];
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher2" periodNumber:2]];
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher3" periodNumber:3]];
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher4" periodNumber:4]];
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher5" periodNumber:5]];
    [self.student.classPeriods addObject:[SCHClassPeriod newClassPeriodWithTeacher:@"Teacher6" periodNumber:6]];
    [self.tableViewController loadLoginData];
}

and [self.tableViewController loadLoginData] is found in the my table view controller and looks like this. THIS IS WHERE I AM STUCK.

- (void)loadLoginData
{
    [self.tableView reloadData];
    NSLog(@"loadLoginData");
}

I know this method is being called, and as a result re-calling numberOfRowsInSection.

numberOfRowsInSection:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    self.classPeriods = self.appDelegate.student.classPeriods;
    NSLog(@"numberOfRowsInSection returns %ld", (long)self.classPeriods.count);

    // Return the number of rows in the section.
    return self.classPeriods.count;
}

cellForRowAtIndexPath:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"prototypeCell" forIndexPath:indexPath];
    SCHClassPeriod *tempPeriod = [self.classPeriods objectAtIndex:indexPath.row];
    NSLog(@"cellForRowAtIndexPath returns %@", tempPeriod.teacher);

    // Configure the cell...
    cell.textLabel.text = tempPeriod.teacher;

    return cell;
}

The only message not being called is the cellForRowAtIndexPath. It is not originally called because there are no objects in the classPeriods array. This is intentional. However, I need cellForRowAtIndexPath to be called when reloadData is called and its not even though numberOfRowsInSection is.

Sorry for the code dump. I want to make sure all the information necessary to answer this question is present. I've been working on this problem for a couple of days now and all similar questions to this seem to be specific to each project.

EDIT: Console Log:

numberOfRowsInSection returns 0

numberOfRowsInSection returns 6

loadLoginData

Login Successful!

Upvotes: 9

Views: 15432

Answers (3)

William Falcon
William Falcon

Reputation: 9823

If reloadData doesn't call cellForRowAtIndexPath, then you haven't linked up the datasource or are not talking to the correct table.

Upvotes: 5

Peter Schultz
Peter Schultz

Reputation: 219

I figured mine out. I connected everything via Storyboard Connections Inspector, but the tutorial that taught me this also told me to add this to the class's viewDidLoad : 

self.tableView.delegate = self;

self.tableView.dataSource = self;

When I deleted these two lines of code, everything worked like a charm!

Now I call the [self.tableView reloadData] method in the viewWillAppear and it works even when going back and forth through segues.

Hope this helped anyone!

Upvotes: 3

meda
meda

Reputation: 45500

In the storyboard drag the from the UItableview to the property called tableView so that when you call [self.tableView reloadData] the outlet will know which table to reload

Upvotes: 0

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