Redraw with new properties - Cocoa/Objective C

Say that I have this view called "MyView". And I have these three dropdowns called "Shadow", "Color" and "Border".

Whenever I change one of these dropdowns I want the view to update with the selected property! How do I do this? I'm currently just able to draw a square in the view :(

Please help m开发者_Go百科e out on this one!

Thank you!

Each time you change a value - call [myRectangleView setNeedsDisplay:YES]. This way your app will know that it needs to redraw the view and once it does - it will use newly set values.