Xcode ios Unknown type name?
You probably have a circular dependency/include. Use a forward declaration (@class MONClass;) rather than #importing the header. Since there is no physical dependence, you should be using a forward declaration in the first place (i.e. for much faster builds).
So instead of:
#import "VistaDereIzq.h"use:
@class VistaDereIzq;and then add your #import to an .m file as needed.