what is the program flow in Cocoa Applcation

Question

Hi,

I am new to mac os X development ,I downloaded an open source mac application ,but i couldn't able to understand the flow of execution of cocoa program.so any one can explain the program flow of a general cocoa program briefly.

Thanks in advance

Answer 1

Start in main. It's not likely to contain anything interesting, but worth checking just in case. Most probably, it will contain only a call to NSApplicationMain, which will create the NSApplication object and send it a run message. That's what gets the application running, and this method will run for the rest of the rest of the process.

Then look in the MainMenu nib. Loading this is one of the first things the application will do. Any windows here that are set as “Visible on Launch” will come up immediately; more importantly, the application delegate will probably be here. Check the application's or File's Owner's (the application is both of them in this nib, so you need to check both) delegate outlet, and if one of them is connected, follow the connection. See what class that object is an instance of.

Once you've found the application delegate class, open it up in Xcode. Look through the list of application delegate methods and find which ones are implemented, and read the ones that are. The application:…FinishLaunching: twins will be particularly important at the start of the process.

From there, it's all just reading code, seeing what it does, and going where it takes you.

Answer 2

Peter's answers are good - I'd also say to check for implementations of 'awakeFromNib', especially for object loaded from MainMenu.nib. You often find interesting things stashed away in that method, rightly or wrongly.