CODEWITHSUNDEEP
objective-cc
eagle_bear
eagle_bear

Reputation: 47

Calling Objective-C method from C code

I'm trying to call a method implemented in Obj-C from C code as follows:

// MainViewController.m

- (void)Test
{
    [self outputLine:@"Called from MyCode.c"];
}
.
.
.
cFunc(id param);
.
.
.

// MyCode.c

void cFunc(id param)
{
    [param Test]; // compilation error: Parse issue: Expected expression
}

I guess it happens since the MainViewController is not declared in MyCode.c, but when I #include the MainViewController.h I get tons of other errors that suggests I'm totally wrong... How should I handle it correctly?

TIA

Upvotes: 0

Views: 275

Answers (3)

Nico Cvitak
Nico Cvitak

Reputation: 471

Just change your myCode.c to myCode.m :P

Don't be afraid to put C code in an Objective-C file.

Upvotes: 0

George Mitchell
George Mitchell

Reputation: 1168

Check: using objc_msgSend to call a Objective C function with named arguments

void cFunc(id param) {
    objc_msgSend(param, sel_getUid("Test"));
}

But, as per the link above, this is dangerous for a few reasons, if your arguments don't fit in registers (i.e. floats, structs, blah blah).

The accepted way of doing this is to cast objc_msgSend:

void cFunc(id param) {
    // Now let's pretend that you want to send someFloat to your method

    void (*objc_msgSendTyped)(id self, SEL _cmd, float bar) = (void*)objc_msgSend;

    float someFloat = 42.f;
    objc_msgSendTyped(param, sel_getUid("Test"), someFloat);
}

Upvotes: 0

user529758
user529758

Reputation:

You should compile the MyCode.c file as Objective-C. Objective-C is a superset of C, but it's not true the other way around. You can't have Objective-C code interspersed with your "pure C" code if you are intending to compile it as C.

Upvotes: 4

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