vtable C++ error after implementing pure virtual method - c++

Question

I have a pure virtual function defined in a class as below:
template <typename T>
class PositioningMethod {
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) = 0;
};
and implementing it in ParticleFilter as below:
class ParticleFilter:public PositioningMethod<T> {
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) {
/*Some code and return*/
return ApproximatePosition::from(xxxx, xxxx, xxxx());
}
};
but getting below errors:
"ParticleFilter<KnownBluetoothBeacon<CartesianLocation>, RadioProximity<BluetoothBeacon>
>::getPosition(std::__1::list<RadioProximity<BluetoothBeacon>*, std::__1::allocator<RadioProximity<BluetoothBeacon>*> >&)", referenced from:
vtable for RadioProximityParticleFilter in lib.a(RadioProximityParticleFilter.o)
"ParticleFilter<KnownBluetoothBeacon<CartesianLocation>, RadioProximity<BluetoothBeacon>
>::ParticleFilter(std::__1::list<KnownBluetoothBeacon<CartesianLocation>, std::__1::allocator<KnownBluetoothBeacon<CartesianLocation> > >&, double)", referenced from:
RadioProximityParticleFilter::RadioProximityParticleFilter(std::__1::list<KnownBluetoothBeacon<CartesianLocation>, std::__1::allocator<KnownBluetoothBeacon<CartesianLocation> > >&, double) in lib.a(RadioProximityParticleFilter.o)
ld: symbol(s) not found for architecture arm64
I know vtable error generally occurs on non-implementing pure virtual functions, but in my case it is same. Any idea where I may be wrong?
Note: The above errors I am getting while integrating my C++ code with objective C in iOS. While in C++ its working fine
This below line is causing the errors in ViewController.mm:
RadioProximityParticleFilter *obj = new RadioProximityParticleFilter (*asList,50);

Answer 1

I completed your code to use it in my MS VS 2013 test project, and it just works - here is the full listing:
#include <iostream>
#include <list>
using namespace std;
class ApproximatePosition
{
public:
static ApproximatePosition *from( int a, int b, int c)
{
cout << "from called." << endl;
return NULL;
}
};
class ListElem{};
template <typename T>
class PositioningMethod
{
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) = 0;
};
template <typename T>
class ParticleFilter :public PositioningMethod<T>
{
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals)
{
/*dummy input and return*/
int a = 0, b = 0, c = 0;
cout << "getPosition called." << endl;
return ApproximatePosition::from( a, b, c );// xxxx, xxxx, xxxx());
}
};
int main()
{
PositioningMethod<ListElem> *pm = new ParticleFilter<ListElem>();
std::list<ListElem*> l;
pm->getPosition( l );
}
The output is:
getPosition called.
from called.