Angle.swift

import UIKit

postfix operator °

protocol IntegerInitializable: ExpressibleByIntegerLiteral {
    init (_: Int)
}

extension Int: IntegerInitializable {
    postfix public static func °(lhs: Int) -> CGFloat {
        return CGFloat(Measurement(value: Double(lhs), unit: UnitAngle.degrees)
            .converted(to: .radians).value)
    }
}

let angle = 45°
let contentView = UIView()
contentView.transform = CGAffineTransform(rotationAngle: 45°)