_NSCFConstantString latitude]: unrecognized selector sent to instance

Question

for(int i=0;i<[self.printers count]; i++)
    {
        PublicPrivateEvent *printerselection = [printers objectAtIndex:i];

        CGFloat latt = [printerselection.latitude floatValue]; //Here is broken
        CGFloat lng=[printerselection.longtitude floatValue];
         pointsCoOrds[index++] = CLLocationCoordinate2DMake(latt,lng);

    }

Hi All, Im trying to get the value from PublicPrivateEvent class. But I dont know for what I cant handle it? I have this problem: _NSCFConstantString latitude]: unrecognized selector sent to instance .. DO you have any idea? Thanks in advance.