Swift 4：根据Picker View选择结果显示/隐藏按钮的实现问题

没问题，我来帮你把这个功能完整实现好，咱们一步步梳理清楚：

1. 先准备基础数据与协议 #

首先，咱们需要定义教育水平的数据源数组，同时确保你的ViewController遵守UIPickerViewDataSource和UIPickerViewDelegate协议：

import UIKit

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
    // 教育水平选项
    private let educationLevels = ["High School", "College Graduate", "Postgraduate"]
    // 本科及以上学位选项
    private let collegeDegreeTitles = ["associates degree", "bachelor's degree", "master's degree"]
    
    // 声明学位按钮为属性，方便后续控制显示/隐藏
    private var associatesBtn: UIButton!
    private var bachelorBtn: UIButton!
    private var masterBtn: UIButton!
    
    // 你的PickerView实例，假设已经在Storyboard或代码中创建
    @IBOutlet weak var educationPicker: UIPickerView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // 设置PickerView的数据源和代理
        educationPicker.dataSource = self
        educationPicker.delegate = self
        
        // 初始化并布局学位按钮
        setupDegreeButtons()
        // 默认隐藏按钮
        hideDegreeButtons()
    }
}

2. 实现PickerView的数据源方法 #

修正你原来代码里的语法错误，正确实现PickerView的标题返回方法：

// PickerView列数（这里我们只需要1列）
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

// PickerView每行的选项数量
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return educationLevels.count
}

// 返回每行显示的标题
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return educationLevels[row]
}

3. 初始化学位按钮 #

在setupDegreeButtons方法里创建三个按钮，设置好布局和样式（这里用Frame做简单示例，你也可以换成AutoLayout适配不同屏幕）：

private func setupDegreeButtons() {
    let btnWidth: CGFloat = 180
    let btnHeight: CGFloat = 40
    let startY: CGFloat = 200
    let centerX = (view.frame.width - btnWidth) / 2
    
    // 创建associates degree按钮
    associatesBtn = UIButton(type: .system)
    associatesBtn.setTitle(collegeDegreeTitles[0], for: .normal)
    associatesBtn.frame = CGRect(x: centerX, y: startY, width: btnWidth, height: btnHeight)
    // 绑定点击事件
    associatesBtn.addTarget(self, action: #selector(degreeBtnTapped(_:)), for: .touchUpInside)
    view.addSubview(associatesBtn)
    
    // 创建bachelor's degree按钮
    bachelorBtn = UIButton(type: .system)
    bachelorBtn.setTitle(collegeDegreeTitles[1], for: .normal)
    bachelorBtn.frame = CGRect(x: centerX, y: startY + 50, width: btnWidth, height: btnHeight)
    bachelorBtn.addTarget(self, action: #selector(degreeBtnTapped(_:)), for: .touchUpInside)
    view.addSubview(bachelorBtn)
    
    // 创建master's degree按钮
    masterBtn = UIButton(type: .system)
    masterBtn.setTitle(collegeDegreeTitles[2], for: .normal)
    masterBtn.frame = CGRect(x: centerX, y: startY + 100, width: btnWidth, height: btnHeight)
    masterBtn.addTarget(self, action: #selector(degreeBtnTapped(_:)), for: .touchUpInside)
    view.addSubview(masterBtn)
}

// 按钮点击事件处理
@objc private func degreeBtnTapped(_ sender: UIButton) {
    if let title = sender.titleLabel?.text {
        print("选中的学位：\(title)")
        // 这里可以添加你需要的逻辑，比如更新页面标签、保存用户选择等
    }
}

4. 实现PickerView选中事件的核心逻辑 #

当用户选中College Graduate时显示按钮，选择其他选项则隐藏：

// 选中PickerView某一行时触发
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let selectedLevel = educationLevels[row]
    if selectedLevel == "College Graduate" {
        showDegreeButtons()
    } else {
        hideDegreeButtons()
    }
}

// 显示所有学位按钮
private func showDegreeButtons() {
    associatesBtn.isHidden = false
    bachelorBtn.isHidden = false
    masterBtn.isHidden = false
}

// 隐藏所有学位按钮
private func hideDegreeButtons() {
    associatesBtn.isHidden = true
    bachelorBtn.isHidden = true
    masterBtn.isHidden = true
}

关键注意点 #

• 你原来的代码里有语法错误：Swift 3+的PickerView标题方法签名是pickerView(_:titleForRow:forComponent:)，不是旧的命名方式
• 不要直接比较row的数值，而是通过数组拿到选中的字符串，这样后续修改数组顺序也不会影响逻辑
• 按钮要提前初始化并默认隐藏，避免出现空指针异常

内容的提问来源于stack exchange，提问作者yukimoda