Inheritance from non-protocol, non-class type ‘CGPoint’

This is not possible because you want to inherit a struct from a class. CGPoint is a struct and therefore it does not support inheritance, although it can conform to protocols.

If you really want to do this, use composition instead of inheritance.

class IYAttachPoint {

  var point:CGPoint?
  var holder: String = "No holder"
  var unavailable: Bool = false
}