Question

我想用嵌套数据和2个组件构建一个UIPicker。第二个组件应依赖于第一个组件的选择（例如，当选择水果时->显示香蕉，苹果...；当选择蔬菜时->显示西红柿...）。

这可行，但是第二个组件的UI不会直接更新。我必须点击第二个组件才能看到标题。选择后，我尝试更新组件（picker.reloadComponent(1)）和所有组件picker.reloadAllComponents()。

有什么想法吗？

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    @IBOutlet weak var picker: UIPickerView!

    var plants = [Dictionary<String, Any>]()
    var groups:[String] = [String]()

    override func viewDidLoad() {
        super.viewDidLoad()

        plants.append([
            "name": "Fruits",
            "groups": [
                "Banana",
                "Apple"
            ]
        ])
        plants.append([
            "name": "Veggies",
            "groups": [
                "Tomatoe",
                "Salad",
                "Cucumber"
            ]
        ])

        if plants[0]["groups"] != nil {
            groups = plants[0]["groups"] as! Array
        }

        picker.delegate = self
        picker.dataSource = self
    }

    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 2
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if component == 0 {
            return plants.count
        } else if component == 1 {
            return groups.count
        }

        return 0
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if component == 0 {
            // Update groups array, based on selection
            if plants[row]["groups"] != nil {
                groups = plants[row]["groups"] as! Array
            }

            picker.reloadComponent(1) //also tried picker.reloadAllComponents() here
        }
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if component == 0 {
            if plants[row]["name"] != nil {
                return plants[row]["name"] as! String
            }
        } else if component == 1 {
            // return values of current group
            return groups[row]
        }

        return ""
    }
}

谢谢！

Answer 1

Swift 4.2 / xCode 10

您的代码可以正常工作。如果您的问题是希望将第二个组件重新加载到第一个组件，请在picker.reloadComponent(1)之后尝试：

picker.selectRow(0, inComponent: 1, animated: true)

否则，请更具体地说明问题。

UIPickerView取决于第一个组件不会更新UI

1 个答案: