CODEWITHSUNDEEP
objective-c
user1170015
user1170015

Reputation: 21

Invalid selector sent to instance

I am creating a applications for teachers that will store Courses and students as well as keep track of grades. Right now it is set up in a data model that stores the courses in an array. The courses are objects that include an array of students and assignments. I have a tableview of all the courses that transitions to a tableview of students. In the courses detail view I have a tableview cell that transitions to a third table view for the assignments. My problem is occurring here. When I try to add an assignment to the tableview I am getting the error: 'NSInvalidArgumentException', reason: '-[__NSArrayI addObject:]: unrecognized selector sent to instance 0x6b38620'..

Here is some code that I believe may contain the problem.

Course detail view controller:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:@"AssignmentTable"]) {

    AssignmentViewController *controller = segue.destinationViewController;
    controller.checklist = checklistToEdit;

}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if(indexPath.row == 2)
    {
    [self performSegueWithIdentifier:@"AssignmentTable" sender:checklistToEdit];


    }
}

Assignment View controller:

- (void)editAssignmentViewController:(EditAssignmentViewController *)controller     didFinishAddingItem:(Assignment *)item
{
int newRowIndex = [self.checklist.assignments count];

[self.checklist.assignments addObject:item];

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:newRowIndex inSection:0];
NSArray *indexPaths = [NSArray arrayWithObject:indexPath];
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];


[self dismissViewControllerAnimated:YES completion:nil];
}

Assignment Detail View Controller:

- (IBAction)done
{
if (assnToEdit == nil) {
    Assignment *item = [[Assignment alloc] init];
    item.texta = self.textFielda.text;

    [self.delegate editAssignmentViewController:self didFinishAddingItem:item];


} else {
    self.assnToEdit.texta = self.textFielda.text;

    [self.delegate editAssignmentViewControllerDidCancel:self]; 
}

}

Upvotes: 0

Views: 160

Answers (1)

jlehr
jlehr

Reputation: 15597

The object you've stored in the assignments property is an instance of NSArray, which is immutable. You need that to be an instance of NSMutableArray instead. That's the reason addObject: is an unrecognized selector -- it's a method that exists in NSMutableArray but not in NSArray and your code is sending it to an instance of NSArray.

Upvotes: 2

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