Using UIBezierPath:byRoundingCorners: with Swift 2 and Swift 3

Swift 2:

let buttonPath = UIBezierPath(roundedRect: button.bounds, 
                              byRoundingCorners: [.TopLeft , .BottomLeft], 
                              cornerRadii: CGSizeMake(1.0, 1.0))

Swift 3 and Swift 4:

let buttonPath = UIBezierPath(roundedRect: button.bounds, 
                              byRoundingCorners: [.topLeft ,.bottomLeft], 
                              cornerRadii: CGSize(width:1.0, height:1.0))

In this case in swift 2.0 is required to make union of two corners. F. ex.:

let corners = UIRectCorner.TopLeft.union(UIRectCorner.BottomLeft)
let buttonPath = UIBezierPath(roundedRect: button.bounds, 
                              byRoundingCorners: corners,
                              cornerRadii: CGSizeMake(1.0, 1.0))

Works with Swift 2 and Swift 3