Example swift exception throw and catch.

ExceptionTestSwift.swift

enum ArrayError : ErrorType{
  case OutOfBounds
}

class SomeClass {

  var test: NSArray! = ["Test1", "Test2"]

  func testCode() {

    do{
      try testing(3)
    } catch let error{
      print("error = \(error)") // for index 3 this would print "error = OutOfBounds\n"
    }

  }

  func testing(index: Int) throws -> String {

    guard index < test.count else{
      throw ArrayError.OutOfBounds
    }

    return test[index] as! String
  }

}

let sC = SomeClass()
sC.testCode()
// Credit to: http://stackoverflow.com/users/1066899/the-critic