Playground

首次公布于WWDC2016，最开始是为了让人人都能愉快的学习Swift编程，但发展至今，这个工具越来越强大

import UIKit

var str = "Hello, playground"
func addTwoNum(num1 : Int, num2 : Int) -> Int {
    return num1 + num2
}
let sum = addTwoNum(num1: 100, num2: 200)
print(sum)

class Person {
    var name : String
    var age : Int
    init(name: String, age:Int) {
        self.name = name
        self.age = age
    }
}
// 格式化输入字符串
extension Person : CustomStringConvertible {
    var description: String {
        get {
            return "\(name) age \(age)"
        }
    }
}

let zhangsan = Person(name: "zhangsan", age: 23)

Playground-Live View

可以用来进行UI的编程
ViewController1.swift

import Foundation
import UIKit

public class ViewController1: UIViewController {
    public override func viewDidLoad() {
        super.viewDidLoad()
        let button = UIButton(type: .custom)
        button.frame = CGRect(x: 0, y: 200, width: 300, height: 50)
        button.setTitle("点击跳转", for: .normal)
        button.setTitleColor(.white, for: .normal)
        button.backgroundColor = .blue
        button.addTarget(self, action: #selector(buttonClick), for: .touchUpInside)
        view.addSubview(button)
    }
    
    @objc func buttonClick() {
        navigationController?.pushViewController(ViewController2(), animated: true)
    }
}

ViewController2.swift

import Foundation
import UIKit

public class ViewController2: UIViewController {
    public override func viewDidLoad() {
        super.viewDidLoad()
        let label:UILabel = UILabel()
        label.frame = CGRect(x: 0, y: 100, width: 300, height: 50)
        label.text = "页面2"
        label.textColor = .white
        label.backgroundColor = .red
        view.addSubview(label)
    }
}

playground

import UIKit
import PlaygroundSupport

let vc = ViewController1()
let navVC = UINavigationController(rootViewController: vc)
PlaygroundPage.current.liveView = navVC