In visual studio there is an event called text_changed for text boxes, how can I create a similar event/Action in Cocoa?
And in general how do you get these extra events for form controls? e.g. mouse over, in visual studio you just choose from a list of events.
You want to set yourself (i.e. the app delegate, or whatever controller you've got for managing that view) as the delegate of your NSTextField. Then implement the method
- (void)controlTextDidChange:(NSNotification *)aNotification
It gets called whenever the text in the text field changes.
For an introduction to handling mouse events, such as mouse over, the Cocoa Event Handling Guide is a pretty good starting point.