Ios 使用UIBezierPath:byRoundingCorners:Swift 2和Swift 3

我用这个代码使一个按钮的两个角变圆

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

它抛出一个错误：

二进制运算符“|”不能应用于两个UIRecentCorner操作数

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如何在Swift 2.0中使用此方法？

Swift 2:

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

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

Swift 3和Swift 4:

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

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

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在这种情况下，swift 2.0中需要使两个角接合。F.例如：

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

与Swift 2和Swift 3配合使用