Question

I was reading the docs to learn how to add a row in a table view, and I found this example :

- (void)save:sender {

    UITextField *textField = [(EditableTableViewTextField *)[tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]] textField];

    SimpleEditableListAppDelegate *controller = (SimpleEditableListAppDelegate *)[[UIApplication sharedApplication] delegate];
    NSString *newItem = textField.text;

    if (newItem != nil) {
        [controller insertObject:newItem inListAtIndex:[controller countOfList]];
    }

    [self dismissModalViewControllerAnimated:YES];

}

I don’t understand the method : insertObject:inListAtIndex: or what [[UIApplication sharedApplication] delegate]; stands for; are we putting the data in a plist file? Could someone explain this to me? The UIApplication docs do not really help.

Answer 1

[[UIApplication sharedApplication] delegate] is the main application delegate, typically this is a class named AppDelegate. The main application delegate is the one that is created on application start-up and which is the main controller for your application.

I’m going to assume that you’re using something similar to this class as your AppDelegate class.

[controller insertObject:newItem inListAtIndex:[controller countOfList]];

This assumes that your AppDelegate class has a method named insertObject:inListAtIndex: on it. For the class I linked the method looks like this:

- (void)insertObject:(id)obj inListAtIndex:(NSUInteger)theIndex {
    [list insertObject:obj atIndex:theIndex];
}

So in this case, that method is adding the object to a member variable of your AppDelegate class called List.