Working with multiple Windows Using Interface Builder

How to work with multiple windows in Cocoa? I have created a cocoa application. When I run that application it automatically shows a default window. I've added a button in the window. When I click the button I want to open another window named MySecondWindow which I created in IB..

I created Window controller (MySecondWindowController) for MySecondWindow and linked it to the nib in IB. When I click the button in my main window, I am calling an IBAction that creates an instance of MySecondWindowController and calling the N开发者_Python百科SApp beginSheet: method with [mySecondWindowObj window]. I am getting the Modal session requires modal window message in NSlog. When I try to print [mySecondWindowObj window] in NSLog, it prints null..

I don't know what to do. What are the necessary things should be done to make this work? I need help..

Thanks..

YourWindowController* sheet;

[[NSApplication sharedApplication] beginSheet:[sheet window]
                               modalForWindow:[[NSApplication sharedApplication] mainWindow]
                                modalDelegate:nil
                               didEndSelector:nil
                                  contextInfo:nil];

Make sure your window is getting properly instantiated. Make sure the "Visible At Launch" option in IB isn't checked.

EDIT: I just noticed you're loading this window from a separate nib file. Make sure you're loading it properly. Use this:

YourWindowController* sheet = [[YourWindowController alloc] initWithWindowNibName:@"NameOfNibMinusExtension"];

ALSO:

Check and make sure the "File Owner" type is set to your custom window controller's classname, and that it's "window" is set to the window in the Nib.

Right-Click (or Cmd+Click) on File's Owner, and ensure the "window" property is connected to the corresponding window. Also, once again, make sure that the window's "Visible on Launch" is NOT checked.

Hold down the Control key, click and hold on the button, then drag a line over to MySecondWindow. It'll give you a little black box full of methods: choose makeKeyAndOrderFront:.

What this does is it makes the button (an instance of NSButton) send the makeKeyAndOrderFront: message to the window when you click the button. The button is a subclass of NSControl which implements what is called the target/action system in Cocoa. Interface Builder, when you drag the line, sets the target of the button to be MySecondWindow, and the action to be makeKeyAndOrderFront:. NSButton is then programmed internally to send the action message to the target when it receives a click.

Make sense?