_before.swift

    func viewDidLoad() {
        super.viewDidLoad()

        let currentEnvironment = EnvironmentManager.currentEnvironment()
        
        self.selectSegmentForEnvironment(currentEnvironment)
        // Do any additional setup after loading the view.
    }
    
    func selectSegmentForEnvironment(environment:Environment) {
        let index: Int
        
        switch environment.vintage {
        case .Production :
            index = 0
        case .Staging:
            index = 1
        case .Local:
            index = 2
        }
        
        self.environmentSelectionControl.selectedSegmentIndex = index

    }

after.swift

extension EnvironmentVintage {
    private func segmentIndex() -> Int{
        let index: Int
        
        switch self {
        case .Production :
            index = 0
        case .Staging:
            index = 1
        case .Local:
            index = 2
        }
        return index

    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    let currentEnvironment = EnvironmentManager.currentEnvironment()
    
    self.environmentSelectionControl.selectedSegmentIndex = currentEnvironment.vintage.segmentIndex()
  // Do any additional setup after loading the view.
}