swift不改UIButton的大小，扩大按钮响应范围

class MyButton: UIButton {
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        let margin: CGFloat = 5
        //负值是方法响应范围
        let area = self.bounds.insetBy(dx: -margin, dy: -margin)
        return area.contains(point)
    }
}