Distinction in Swift between uppercase “Self” and lowercase “self”

Question

While playing in a Swift playground I noticed that Self, with capital \"S\", is available along with the lowercase self. Is there any difference be

Answer 1

in protocol & Extension declaration use Self else self

extension protocolName where Self: UIView 
{
  func someFunction()
  {
    self.layer.shadowColor = UIColor.red.cgColor
  }
}