通过小项目开发的实例，学习swift。

为大家分享swift实现简单的计算器项目，具体如下：

//
//  ViewController.swift
//  计算器
//
//  Created by yaoyezhifan on 2022/8/23.
//

import UIKit

class ViewController: UIViewController {
    var numOne = UITextField()
    var numTwo = UITextField()
    var sum = UILabel()
    var cleanButton = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        //创建第一个输入的加数，即创建文本框
        let numOne = UITextField(frame: CGRect(x: 35, y: 120, width: 75, height: 35))
        numOne.placeholder = "输一个数"
        numOne.layer.borderColor = UIColor.lightGray.cgColor//边框色
        numOne.layer.borderWidth = 2//边框的宽度
        numOne.layer.cornerRadius = 5//边框的弧度
        self.view.addSubview(numOne)//向view画面中，添加文本框
        numOne.keyboardType = UIKeyboardType.numberPad//设定输入键盘为数字型
        self.numOne = numOne//通过self保存创建的文本框
 
        //创建“+”号标签
        let add = UILabel(frame: CGRect(x: 130, y: 120, width: 40, height: 30))
        add.text = "+"
        add.font.withSize(20)//字体大小
        self.view.addSubview(add)//向view画面中，添加标签
   
        // 第二个数
        let numTwo = UITextField(frame: CGRect(x: 165, y: 120, width: 75, height: 35))
        numTwo.placeholder = "输一个数"
        numTwo.layer.borderColor = UIColor.lightGray.cgColor//边框色
        numTwo.layer.borderWidth = 2//边框的宽度
        numTwo.layer.cornerRadius = 5//边框的弧度
        self.view.addSubview(numTwo)//向view画面中，添加文本框
        numTwo.keyboardType = UIKeyboardType.numberPad//设定输入键盘为数字型
        self.numTwo = numTwo//通过self保存创建的文本框
        
        //创建“=”号标签
        let equalTo = UILabel(frame: CGRect(x: 275, y: 120, width: 40, height: 30))
        equalTo.text = "="
        equalTo.font.withSize(20)//字体大小
        self.view.addSubview(equalTo)//向view画面中，添加标签
        
        // sum  和
        let sum = UILabel(frame: CGRect(x: 310, y: 120, width: 40, height: 30))
        sum.textAlignment = .center//对齐方式：居中对齐
        sum.font.withSize(20)//字体大小
        sum.text = "0"
        self.view.addSubview(sum)//向view画面中，添加标签
        sum.layer.borderWidth = 2//边框的宽度
        sum.layer.borderColor = UIColor.lightGray.cgColor//边框色
        self.sum  = sum
        
        // “计算”按钮，点击后实现计算功能
        let button: UIButton = UIButton(frame: CGRect(x: 145, y: 200, width: 100, height: 40))
        self.view.addSubview(button)
        button.backgroundColor = UIColor.lightGray//边框色
        button.setTitle("计算", for: .normal)//按钮title
        button.setTitleColor(.black, for: .normal)//按钮title色
        button.addTarget(self, action: #selector(Onclick), for: .touchUpInside)//点击按钮触发事件
    }

    //点击“计算”按钮方法实现
    @objc func Onclick () {
        let sum = NSString(string: self.numOne.text ?? "").intValue + NSString(string: self.numTwo.text ?? "").intValue
        self.sum.text = String(String(sum))//计算总和并显示
        self.addCleanButton()//添加清除按钮
    }
    
    //清除按钮
    func addCleanButton(){
        let cleanButton:UIButton = UIButton(frame: CGRect(x: 145, y: 250, width: 100, height: 40))
        cleanButton.setTitle("清除", for: .normal)//按钮title
        cleanButton.setTitleColor(.red, for: .normal)//按钮title色
        self.view.addSubview(cleanButton)
        cleanButton.addTarget(self, action: #selector(cleanButtonClick), for: .touchUpInside)//点击按钮触发事件
        self.cleanButton = cleanButton
 
    }
    
    //清除按钮方法实现
    @objc func cleanButtonClick(){
       self.sum.text = "0"
       self.numOne.text = ""
       self.numTwo.text = ""
       if(self.sum.text=="0"){
           self.cleanButton.isHidden = true

       }
    }
}

最终实现结果：

自我感觉可以看的懂，希望对初学者有帮助～～