ios - 在单独的 UICollection 类中使用未解析的标识符 'UICollection'

Question

我有这门课，我将在顶部菜单 View 上工作。

这是代码:

import UIKit

class TopHomeMenuBar: UIView {

let collectionView: UICollectionView = {

    let layout = UICollectionViewFlowLayout()
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
    return cv
}()

override init(frame: CGRect) {
    super.init(frame: frame)

    addSubview(collectionView)

    backgroundColor = UIColor.systemGreen
}

required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}
}

但是，我不断收到错误消息:

使用未解析的标识符“UICollection”

错误是在这行代码中突出显示 UICollectionView:

    let collectionView: UICollectionView = {

Answer 1

它确实有效

现在在 XCODE 中创建了一个简单的 SinlgerView 项目
我放的 Controller (仅用于测试..通常 View 有自己的文件..)

//
//  ViewController.swift
//
//  Created by ing.conti on 11/06/2020.
//  Copyright © 2020 ing.conti. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }


}


class TopHomeMenuBar: UIView {

    let collectionView: UICollectionView = {

        let layout = UICollectionViewFlowLayout()
        let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
        return cv
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        addSubview(collectionView)

        backgroundColor = UIColor.systemGreen
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}