The error message is pretty explicit:
'Collision' does not contain a definition for 'collidor' and no accessible extension method 'collidor' accepting a first argument of type 'Collision' could be found
And what it means is what it says: the class
Collision
does not contain a property called
collidor
Remember, c# is case sensitive, so
collidor
is not the same as
Collidor
- so check the class to see what is defined.
Or perhaps it's miss-spelled? Again, check the
Collision
class to see what is available.
While you are there, check the access modifier on the property: if it is
private
for example, it is only accessible within the
Collision
class.