除了WWDC，我还可以去哪里进行实践可可培训？

I'm banging my head up against Cocoa and Xcode, and have been for months. I never seem to be able to get away from the tutorials, which are often incomplete, or Apple developer documentation, which is sparse on samples. I've watched videos, downloaded source code and asked developers for help. I still feel like I haven't gotten that audible "click" when something falls into place. Maybe I'm too old to learn something new, but I feel pretty productive in .Net!I'm banging my head up against Cocoa and Xcode,