What mark up language is there for Mac Os developers?

Question

• So Adobe gives GIVES US mxml FOR AIR ( Flash ) design/development (cross platform, ActionScript)

• Microsoft gives us XAML for .Net design/development (Windows, Silverlight, C# + VB+ F# +...)

• What mark up language gives us Apple for design/development of our Mac native apps?!?

Answer 1

It's called nib (older version) or xib (more recent, XML version) and you can edit it using Interface Builder. People don't usually view them as markup languages, because conceptually the file describes a freeze-dried GUI objects rather than a markup language describing the GUI. But it fills the same position as them.