Define variables in objective-c m file

Always in order to facilitate the implementation of a method, the way to define the variable at the top of the method, that this should and H file definition is the same, in fact, is defined in the M file variable is static, the class of multiple objects will be access to the same variable. The encapsulation of the slot OC is far from Java, and there is no concept of package, sometimes importing other people's code, their own code and others define the same name of the macro. There is no private method, Performselector can execute any method.