[IOS]PickerView 搭配動畫達到上滑選單效果

extension AddProductViewController:UIPickerViewDelegate,UIPickerViewDataSource{
    //設定有幾個bar可以滾動
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    //設定bar的內容有幾項
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return list.count
    }
    //設定bar的內容
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return list[row]
    }
    //調整pickerview文字
    func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
        var label = UILabel()
        if let v = view as? UILabel { label = v }
        label.font = UIFont (name: "Helvetica Neue", size: 25)
        label.text =  list[row]
        label.textAlignment = .center
        label.textColor = UIColor.white
        return label
    }
    //設定每個選項的高度
    func pickerView(_ pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
        50
    }
}

//popoverview榜定
    @IBOutlet var selectView: UIView!
    //popover裡的picker榜定
    @IBOutlet weak var pickerView: UIPickerView!
    //設定popover出來的高度
    let popoverViewHeight = CGFloat(256)

override func viewWillAppear(_ animated: Bool) {
        //加入子視圖(在這裡是要彈出的popoverview)
        view.addSubview(selectView)
        /*在所有有繼承自 UIView 的 object 中都會有一個名為 “translatesAutoresizingMaskIntoConstraints”
        的 property，這 property 的用途是告訴 iOS自動建立放置位置的約束條件，而第一步是須明確告訴它不要這樣做，因此需設為false。*/
        selectView.translatesAutoresizingMaskIntoConstraints = false
        //設定子試圖畫面高度，一定要加.isActive = true 不然排版會沒有用
        selectView.heightAnchor.constraint(equalToConstant: popoverViewHeight).isActive = true
        //設定左右邊界(左邊要是-10)
        selectView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 10).isActive = true
        selectView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -10).isActive = true
        //先設定這個畫面在螢幕bottom下方height高度位置，等等調整這個數值就可以達到由下往上滑出的效果
        //設為變數等等才方便調整
        let constraint = selectView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: popoverViewHeight)
        //設定constraint id
        constraint.identifier = "bottom"
        constraint.isActive = true
        //設定圓角
        selectView.layer.cornerRadius = 10
        super.viewWillAppear(animated)
    }

 //設定彈出的方法 ture就顯示false就藏在下面
    func displayPicker(_ show:Bool){
        for c in view.constraints{
        //  判斷id
            if(c.identifier == "bottom"){
                //判斷彈出
                c.constant = (show) ? -10 : popoverViewHeight
                break
            }
        }
        //設定動畫
        UIView.animate(withDuration: 0.5){
        //立即更新佈局
            self.view.layoutIfNeeded()
        }
    }

//按下位置按鈕後的action
    @IBAction func locationClick(_ sender: Any) {
        currentButton = btnProductLocation
//清除picker舊資料
        list.removeAll()
//更新picker資料
        list = ["台北市","新北市","基隆市","桃園市","臺中市","臺南市","高雄市","新竹縣","苗栗縣","彰化縣","南投縣","雲林縣","嘉義縣","屏東縣","宜蘭縣","花蓮縣","臺東縣","澎湖縣","金門縣","連江縣","新竹市","嘉義市"]
        //刷新pick內容
        pickerView.reloadAllComponents()
        //跳出popoverview
        displayPicker(true)
    }

//popover裡按下完成按鍵的action
    @IBAction func doneClick(_ sender: Any) {
        let title  = list[pickerView.selectedRow(inComponent: 0)]
        currentButton.setTitle(title, for: .normal)
        //關閉pickerview
        displayPicker(false)
    }
    
    //popover裡按下取消按鍵的action
    @IBAction func cancelClick(_ sender: Any) {
        
        //關閉popoverview
        displayPicker(false)
    }