I have an Obj-C object with a bunch of methods inside of it. Sometimes a method needs to call another method inside the same object. I can't seem to figure out how to get a C method to call a Obj-C method...
WORKS: Obj-C method calling an Obj-C method:
[self objCMethod];
WORKS: Obj-C method calling a C method:
cMethod();
DOESN'T WORK: C method calling an Obj-C method:
[self objCMethod]; // <--- this does not work
The last example causes the compiler spits out this error:
error: 'self' undeclared (first use in this function)
Two questions. Why can't the C function see the "self" variable even though it's inside of the "self" object, and how do I call it without causing the error? Much thanks for any help! :)
You really can't use C in Objective-C, since Objective-C is C. The term is usually applied when you write code that uses C structures and calls C functions directly, instead of using Objective-C objects and messages.
You can mix C++ in with Objectiv-C (Objective C++). Write a C++ method in your Objective C++ class that simply calls [context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self. layer]; and call it from your C++.
It's Shorthand writing. In Objective-C, any character , numeric or boolean literal prefixed with the '@' character will evaluate to a pointer to an NSNumber object (In this case), initialized with that value. C's type suffixes may be used to control the size of numeric literals.
An Objective-C method declaration includes the parameters as part of its name, using colons, like this: - (void)someMethodWithValue:(SomeType)value; As with the return type, the parameter type is specified in parentheses, just like a standard C type-cast.
In order for that to work, you should define the C method like this:
void cMethod(id param);
and when you call it, call it like this:
cMethod(self);
then, you would be able to write:
[param objcMethod];
In your cMethod
.
This is because the self
variable is a special parameter passed to Objective-C methods automatically. Since C methods don't enjoy this privilege, if you want to use self
you have to send it yourself.
See more in the Method Implementation section of the programming guide.
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