本节将通过纯代码进行封装自定义View控件，以常用的设置页的item为例，实现UI效果如下：

1、创建SettingView继承自UIView

import UIKit

class SettingView: UIView {

}

2、重写 init() 和 required init?(coder: NSCoder) 方法

纯代码创建SettingView会执行到init()，而required init?(coder: NSCoder)则是用于可视化布局时，所以两个方法都必须重写。

import UIKit

class SettingView: UIView {
    init() {
        super.init(frame: CGRect.zero)
        innerInit()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        innerInit()
    }

    func innerInit() {
        
    }

}

3、约束设置

当视图加入父视图时，才能进行约束设置，故需要重写 didMoveToSuperview()，并在didMoveToSuperview()方法里面编写约束设置。

import UIKit

class SettingView: UIView {
    init() {
        super.init(frame: CGRect.zero)
        innerInit()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        innerInit()
    }

    func innerInit() {
        
    }

    /// 当视图加入父视图时 / 当视图从父视图移除时调用
    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        //添加约束
        
    }
}

4、完整自定义view代码

//
//  SettingView.swift
//  SnapKitTest
//
//  Created by jin on 2024/8/13.
//

import UIKit

class SettingView: UIView {
    
    init() {
        super.init(frame: CGRect.zero)
        innerInit()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        innerInit()
    }
    
    func innerInit(){
        backgroundColor = .white
        addSubview(leftImgView)
        addSubview(rightImgView)
        addSubview(titleView)
    }
    
    /// 当视图加入父视图时 / 当视图从父视图移除时调用
    override func didMoveToSuperview() {
        super.didMoveToSuperview()
        //添加约束
        leftImgView.snp.makeConstraints { make in
            make.left.equalToSuperview().offset(16)
            make.centerY.equalToSuperview()
            
            make.width.equalTo(20)
            make.height.equalTo(20)
        }
        
        titleView.snp.makeConstraints { make in
            make.left.equalTo(leftImgView.snp.right).offset(16)
            make.centerY.equalToSuperview()
        }
        
        rightImgView.snp.makeConstraints { make in
            make.right.equalToSuperview().offset(-16)
            make.centerY.equalToSuperview()
            
            make.width.equalTo(20)
            make.height.equalTo(20)
        }
    }

    ///左侧图标
    lazy var leftImgView: UIImageView = {
        let imageView = UIImageView()
        imageView.image = UIImage(named: "Setting")
        return imageView
    }()
    
    ///右侧图标
    lazy var rightImgView: UIImageView = {
        let imageView = UIImageView()
        imageView.image = UIImage(named: "Arrow")
        return imageView
    }()
    
    ///标题
    lazy var titleView: UILabel = {
        let textView = UILabel()
        textView.text = "标题"
        return textView
    }()
}

5、使用自定义View

view.addSubview(settingView)

//添加约束，只有添加当前控件，内部的约束在控件内部就添加了
settingView.snp.makeConstraints { make in
	make.top.equalTo(view.safeAreaLayoutGuide.snp.top)
	
	make.width.equalToSuperview()
	make.height.equalTo(55)
}

lazy var settingView: SettingView = {
	let view = SettingView()
	view.titleView.text = "设置"
	view.leftImgView.image = UIImage(named: "Setting")
	return view
}()

6、设置View点击事件

@objc func onSettingClick(recognizer:UITapGestureRecognizer) {
	print("onSettingClick")
}
	
lazy var settingView: SettingView = {
	let view = SettingView()
	view.titleView.text = "设置"
	view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(onSettingClick(recognizer:))))
	return view
}()

7、使用自定义View的完整代码

//
//  SettingController.swift
//  SnapKitTest
//
//  Created by jin on 2024/8/13.
//

import UIKit

class SettingController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemGroupedBackground
        title = "设置界面"
        
        view.addSubview(settingView)
        view.addSubview(collectView)
        
        //添加约束，只有添加当前控件，内部的约束在控件内部就添加了
        settingView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide.snp.top)
            
            make.width.equalToSuperview()
            make.height.equalTo(55)
        }
        
        collectView.snp.makeConstraints { make in
            make.top.equalTo(settingView.snp.bottom).offset(1)
            
            make.width.equalToSuperview()
            make.height.equalTo(55)
        }
    }
    
    @objc func onSettingClick(recognizer:UITapGestureRecognizer) {
        print("onSettingClick")
    }
    
    @objc func onCollectClick(recognizer:UITapGestureRecognizer) {
        print("onCollectClick")
    }
    
    lazy var settingView: SettingView = {
        let view = SettingView()
        view.titleView.text = "设置"
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(onSettingClick(recognizer:))))
        return view
    }()
    
    lazy var collectView: SettingView = {
        let view = SettingView()
        view.titleView.text = "收藏"
        view.leftImgView.image = UIImage(named: "Setting")
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(onCollectClick(recognizer:))))
        return view
    }()

}

至此，一个简单的纯代码封装自定义View控件便实现了。