Lock screen in Xcode

Question

Hello
I'm new in Xcode. I would like to make an Lock Screen application.
How can I tell the textfield that when the word 'test' is entered, the program closes.But if Ienter a different word should appear a message.
Example code would be helpful.
Thanks
Mario

Answer 1

For the target application, you'll want to use the frameworks; without intending offense, the only folks that ask for and process passwords directly are usually folks that are trying to steal the user's passwords.  The following is an OpenGL framework for a screensaver: Writing a Screen Saver (part I), Writing a Screen Saver (part II) and here is part of the Apple screen saver framework documentation.  That'll get you some idea of what's involved with using the existing frameworks available here.  Now in fairness, this probably really isn't what you want, if you're just learning Cocoa...
If you're looking to display a dialog box or other window and prompt for input and react to it (and I'd stay away from the "passwords" stuff for now; you're writing the first part of a Guess The Animal-style program, or whatever), that's a fairly straightforward Cocoa application.
Posting an example of what you want is slightly difficult, as the easiest way to do most of what you're after is with the Interface Builder tool and that doesn't post well here; a fair chunk of the generic prompting application is "just" making the connections in IB.  (The amount of source code to do the simplest form of string comparision is a couple of lines around the NSString's isEqualToString method (there's some example code lined at the end of the isEqualToString method definition) as the core test.
If you're new to C and/or Objective C and/or Cocoa programming, I'd suggest one of the available books on Cocoa and Mac OS X programming.  There are various guides and Apple intro material including Your First Mac App, and both Big Nerd Ranch and Pragmatic Programmers have programming books available, and there is online materials such as this course at CocoaDevCentral - that last course is a bit stale, as Xcode has been a moving target recently.)
And there's a veritable goldmine of sample application code available directly in the Xcode-provided documentation.
There is far more development-related traffic in the Apple Developer (Discussion) Forums, and particularly on the various mailing lists including the Cocoa mailing list and particularly in the archives of the mailing list.