You should be able to use NSInvocation for this. Something like:
// Assuming you really need to use a string at runtime. Otherwise, hardcode the selector using @selector()
SEL selector = NSSelectorFromString(@"pathForwardTo1");
NSMethodSignature *signature = [test methodSignatureForSelector:selector];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
[invocation setSelector:selector];
[invocation setTarget:test];
[invocation invoke];
CGMutablePathRef result = NULL;
[invocation getReturnValue:&result];
You can also do it directly with the proper objc_msgSend variant, but NSInvocation is easier (though probably significantly slower).
EDIT: I put a simple little test program here.