为什么我似乎无法取消归档由OS X应用程序归档的iPhone应用程序中的对象？

I'm writing an iPhone app that is mainly centered around grid patterns, so I have a Pattern class which contains an NSMutableArray of NSMutableArrays. This class implements NSCoding, and it seems the following code works just fine in my iPhone app:I'm writing an iPhone app that is mainly center