Iterating over a vector with foreach

Iterating over a vector with foreach

The following code:
std::vector< int > keysDown;
for each ( int currentKey in keysDown )
{
}
is throwing an intellisense error:
1 IntelliSense: a 'for each' statement cannot operate on an expression
of type "std::vector<int, std::allocator<int>>"
but it seems to compile and run, any ideas?