Question

I have class1.m . I declared a method and written in it. Now i need to call it into another class. How can I make it? Can we use extern for it like we use for variables.
Thank you.

Answer 1

You should separate your declaration and definition, and place the declaration for class1 in class1.h. Then, you should include class1.h using #import "class1.h" in your source file for class2. Within class2, you can instantiate and use class1 as follows:

class1* instance_of_class1 = [[class1 alloc] init];
[class1 invokeMyMethod];

When you are done using your instance, be sure to decrement the reference count via release as in:

[instance_of_class1 release];
instance_of_class1 = nil;