如何根据 UIPickerview 选择运行代码？

Posted 2023-02-24

【中文标题】如何根据 UIPickerview 选择运行代码？

【英文标题】：How to run code based on UIPickerview selections?

【发布时间】：2020-06-02 14:09:24

【问题描述】：

我正在制作一个类似于谷歌文档或其他文本编辑器的简单 ios 应用程序。我创建了一个 UIPickerview 来更改字体大小，但后来我意识到当我选择某些东西时，什么也没有发生。那么有什么办法可以做到这一点，这是我的代码

import UIKit

class FirstViewController: UIViewController, UIPopoverPresentationControllerDelegate, UIPickerViewDelegate, UIPickerViewDataSource 


    @IBOutlet weak var fontBTN: UIButton!
    func numberOfComponents(in pickerView: UIPickerView) -> Int 
        return 1
    
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
        return arrayFruits.count
    
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
        return arrayFruits[row]
    
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 

    
    var arrayFruits = [String]()
    @IBOutlet weak var picker: UIPickerView!
    @IBOutlet weak var aligners: UISegmentedControl!

    @IBOutlet weak var foramtters: UISegmentedControl!
    @IBOutlet weak var textView: UITextView!

    var pickerData = ["10", "12", "14", "16", "18", "20", "22", "24", "26", "28", "30", "36", "48", "72"]


    override func viewDidLoad() 
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        self.picker.delegate = self
        self.picker.dataSource = self
        arrayFruits = ["10", "12", "14", "16", "18", "20", "22", "24", "26", "28", "30", "36", "48", "72"]
    


    @IBAction func aligning(_ sender: Any) 
        switch aligners.selectedSegmentIndex 
        case 0:
            textView.textAlignment = .left
        case 1:
            textView.textAlignment = .center
        case 2:
            textView.textAlignment = .right
        case 3:
            textView.textAlignment = .justified
        default: break

        
    

    @IBAction func formating(_ sender: Any) 
        switch foramtters.selectedSegmentIndex 
        case 0:
            textView.font = UIFont.boldSystemFont(ofSize: 14)
        case 1:
            textView.attributedText = NSAttributedString(string: textView.text, attributes:
                [.underlineStyle: NSUnderlineStyle.single.rawValue])
            textView.font = UIFont(name: "Arial", size: 14)
        case 2:
            textView.font = UIFont.italicSystemFont(ofSize: 14)
        default: break

        

    

    @IBAction func fontPicker(_ sender: Any) 
        if picker.isHidden == true 
            picker.isHidden = false
            fontBTN.setTitle("Done", for: .normal)
         else if picker.isHidden == false 
            fontBTN.setTitle("Aa", for: .normal)
            picker.isHidden = true

        
    

我尝试过Switch statement，但我收到错误消息"Expression pattern of type 'Int' cannot match values of type 'UIPickerView?'" 我尝试用谷歌搜索，但没有任何显示，所以我问了这个问题。

switch picker 
        case 0:
            //funtion here
        default:

        

你能帮帮我吗？

【问题讨论】：

didSelectRow 的主体是空的，所以当您在选择器中选择项目时它什么也不做，将您想要的代码移到那里。

我要在那里放一个 switch 语句吗？

你到底想达到什么目的？

更改文本视图的字体大小

【参考方案1】：

考虑以下代码：

class ViewController: UIViewController 
    @IBOutlet weak var picker: UIPickerView!

    @IBOutlet weak var textView: UITextView!
    let data: [CGFloat] = [20, 25, 30]

    override func viewDidLoad() 
        super.viewDidLoad()
        picker.delegate = self
        picker.dataSource = self
    


extension ViewController: UIPickerViewDelegate 
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
        textView.font = UIFont.systemFont(ofSize: data[row])
    


extension ViewController: UIPickerViewDataSource 
    func numberOfComponents(in pickerView: UIPickerView) -> Int 
        return 1
    

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
        return data.count
    

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
        return "\(data[row])"
    

因此，您可以通过实现如上所示的 didSelectRow 方法来运行基于 UIPickerView 选择的代码。编辑： 我已更改代码以更新 textView 的 fontSize。

【参考方案2】：

要根据选择器选择更改 textView 的字体大小，您需要执行以下操作。

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
      if let doubleValue = Double(arrayFruits[row]) 
          let fontSize = CGFloat(doubleValue)
          textView.font = UIFont.systemFont(ofSize: fontSize)