C ++类作为Objective-C类的实例变量

I need to mix Objective-C and C++. I would like to hide all the C++ stuff inside one class and keep all the others plain Objective-C. The problem is that I want to have some C++ classes as instance variables. This means they have to be mentioned in the header file, which gets included by other classes and C++ starts spreading to the whole application. The best solution I was able to come with so far looks like this:I need to mix Objective-C and C++. I would like