Global constants with swift extensions and Implicit Member Expression.

GlobalConstant.swift

extension Double {
    public static let kRectX = 30.0
    public static let kRectY = 30.0
    public static let kRectWidth = 30.0
    public static let kRectHeight = 30.0
}

public func makeRect() -> CGRect {
    return CGRect(x: .kRectX, y: .kRectY, width: .kRectWidth, height: .kRectHeight)
}

extension String {

    // Notifications
    public static let myCustomNotification = "myCustomNotification"

    // URL paths
    public static let myURLPath = "https://www.google.com/"
    public static func myOtherURLPath() -> String { return "https://www.google.com" }
}


extension NSURL {
    public static let myURL = NSURL(string: .myURLPath)
    public static let myOtherURL = NSURL(string: .myOtherURLPath())
    public static func myThirdURL() -> NSURL { return NSURL(string: .myURLPath)! }
}

public func postNotification () {
    NSNotificationCenter.defaultCenter().postNotificationName(.myCustomNotification, object: nil)
}

public func makeRequest() {
    // Can't omit type with just string
    let request = NSMutableURLRequest(URL: NSURL.myURL!)
    let otherReqeust = NSMutableURLRequest(URL: NSURL.myOtherURL!)
    // Can omit with func!
    let thirdRequest = NSMutableURLRequest(URL: .myThirdURL())
}