Deleting tasks, with optional confirmation

deleteCompletedTasks.m

- (void)deleteCompletedTasksWithConfirmation:(id)sender {
    if ([[NSUserDefaults standardUserDefaults] boolForKey:[NSString stringWithFormat:@"%d", AlistoPrefKeyConfirmDeletion]]) {
        UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"Delete completed tasks?" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:@"Delete tasks" otherButtonTitles:nil];
        
        [sheet showFromToolbar:[[self navigationController] toolbar]];
    } else {
        [self deleteCompletedTasks];
    }
}

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
    if (buttonIndex == 0) {
        [self deleteCompletedTasks];
    }
}

- (void)deleteCompletedTasks {
    // item in this case is the actual List displayed by this view controller, so this is a method which deletes all completed tasks from the List
    [item deleteCompletedTasks];
}