为什么 UIPickerView 显示空列表

Question

我创建了两个 UIPickerView 并为每个来源声明。单击标签后，用户应该会看到所选 UIPickerView

的值

override func viewDidLoad() {
        super.viewDidLoad()
        print(monthBoolLabel)
        monthPickerView.dataSource = self
        monthPickerView.delegate = self
        monthPickerView.isHidden = true

        freeDayPickerView.dataSource = self
        freeDayPickerView.delegate = self
        freeDayPickerView.isHidden = true

        let tapMonth = UITapGestureRecognizer(target: self, action: #selector(tapOnMonth(gestureReconizer:)))
        monthLabel.addGestureRecognizer(tapMonth)
        monthLabel.isUserInteractionEnabled = true

        let tapFreeDay = UITapGestureRecognizer(target: self, action: #selector(tapOnFreeDay(gestureReconizer:)))
        freedayLabel.addGestureRecognizer(tapFreeDay)
        freedayLabel.isUserInteractionEnabled = true


        let tapView = UITapGestureRecognizer(target: self, action: #selector(backgroundViewTapped))
        view.addGestureRecognizer(tapView)
}

我声明了检测用户何时点击标签的函数：

@objc func tapOnMonth(gestureReconizer: UITapGestureRecognizer) {
        print("*")
        monthPickerView.isHidden = false
        monthBoolLabel = true
        freedayBoolLabel = false

    }

    @objc func tapOnFreeDay(gestureReconizer: UITapGestureRecognizer) {
        print("*")
        freeDayPickerView.isHidden = false
        freedayBoolLabel = true
        monthBoolLabel = false
    }

我的 ViewController

也得到了扩展

extension HomePageViewController: UIPickerViewDelegate, UIPickerViewDataSource {

    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if freedayBoolLabel == true {
            return freeDaySource.count
        }
        else if monthBoolLabel == true{
            return monthSource.count
        }
        else {
            return 0
        }
    }


    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if freedayBoolLabel == true {
            freedayLabel.text = freeDaySource[row]
        }
        else if monthBoolLabel == true{
            monthLabel.text = monthSource[row]
        }

    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if freedayBoolLabel == true {
            return freeDaySource[row]
        }
        else if monthBoolLabel == true{
            return monthSource[row]
        }
        else {
            return ""
        }
    }

}

无论 UILabel 用户点击哪个，列表总是空的

Answer 1

您需要在点击标签后重新加载选择器视图。

@objc func tapOnMonth(gestureReconizer: UITapGestureRecognizer) {
    print("*")
    monthPickerView.isHidden = false
    monthBoolLabel = true
    freedayBoolLabel = false
    monthPickerView.reloadAllComponents() // add this
}

对另一个也进行类似的更改。

仅供参考 - 您只需要一个选择器视图，而不是两个，因为无论如何您一次只显示一个。

为什么 UIPickerView 显示空列表

Why UIPickerView shows empty list

ios

swift

uipickerview