- example
```.swift
class LineView: UIView {

    override func draw(_ rect: CGRect) {
        layer.cornerRadius = 5
        layer.masksToBounds = true
        // 左側だけ丸くする
        layer.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
        super.draw(rect)
    }

}
```

|プロパティ|角丸になる場所|
|:-----------------:|:------------------:|
|layerMinXMinYCorner|左上|
|layerMaxXMinYCorner|右上|
|layerMinXMaxYCorner|左下|
|layerMaxXMaxYCorner|右下|