Question

I’m creating a a Master-Detail Splitview app and I’m using a UIAlertView in the insertNewObject method to let the user define a title for the new object being added to the master view. I’ve used the code and guide from this question linky by Warkst.

My problem is that when the alert view is called the rest of the insertNewObject function continues to run and therefore creates a new object with a blank title, as it finishes running before the AlertView even has a chance to appear.

The code I’m using is as follows, with the first method being insertNewObject and the second being the method the AlertView calls when the button is pressed. newTitle is a global variable.

- (void)insertNewObject:(id)sender
{
    //Make sure clear before we start, also make sure initalized (double redundancy with clear statement at end)
    newTitle = @"";

    //New Title pop up UIAlert View
    UIAlertView * alert = [[UIAlertView alloc] 
                           initWithTitle:@"New Object" 
                           message:@"Please enter a name for object" 
                           delegate:self 
                           cancelButtonTitle:@"Create" 
                           otherButtonTitles:nil];

    alert.alertViewStyle = UIAlertViewStylePlainTextInput;

    UITextField * alertTextField = [alert textFieldAtIndex:0];

    alertTextField.keyboardType = UIKeyboardTypeDefault;

    alertTextField.placeholder = @"Enter a new title";
    [alert show];

    //Create and enter new object.
    if (!_objects) 
    {
        _objects = [[NSMutableArray alloc] init];
    }

    [_objects insertObject:newTitle atIndex:0];
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];

    //Clear newTitle for use next time
    newTitle = @"";
}

UIAlertView button clicked method

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{ 
    newTitle = [[alertView textFieldAtIndex:0] text];
}

Answer 1

You want to be doing your object creation in the UIAlertViewDelegate method alertView:clickedButtonAtIndex: because (as you noticed) the call to show the alert dos not block the rest of the method from executing.

Also, if it is relevant, you might want to let the user cancel out of the action by adding an additional button.