//In Swift 5.0
let screenSize: CGRect = UIScreen.main.bounds

//Swift 4.0
// Screen width.
public var screenWidth: CGFloat {
    return UIScreen.main.bounds.width
}
// Screen height.
public var screenHeight: CGFloat {
    return UIScreen.main.bounds.height
}

//In Swift 3.0
let screenSize = UIScreen.main.bounds
let screenWidth = screenSize.width
let screenHeight = screenSize.height

//In older swift:
//Do something like this:
let screenSize: CGRect = UIScreen.mainScreen().bounds
//then you can access the width and height like this:
let screenWidth = screenSize.width
let screenHeight = screenSize.height