Helpers for UILayoutPriority for swift 4

UILayoutPriority+operations.swift

extension UILayoutPriority: ExpressibleByFloatLiteral, ExpressibleByIntegerLiteral {
    public init(floatLiteral value: Float) {
        self.init(rawValue: value)
    }

    public init(integerLiteral value: Int) {
        self.init(rawValue: Float(value))
    }

    public static func +(lhs: UILayoutPriority, rhs: UILayoutPriority) -> UILayoutPriority {
        return UILayoutPriority(rawValue: lhs.rawValue + rhs.rawValue)
    }

    public static func -(lhs: UILayoutPriority, rhs: UILayoutPriority) -> UILayoutPriority {
        return UILayoutPriority(rawValue: lhs.rawValue - rhs.rawValue)
    }
}

let view = UIView()
view.setContentCompressionResistancePriority(.defaultHigh + 1, for: .horizontal)