UICollectionView 的应用 demo

collectionView.swift

import UIKit

fileprivate let CellIdentifier = "CellIdentifier"

// MARK: InterCell

class InterCell: UICollectionViewCell {
    lazy var thumbnail: UIImageView = {
        let imageView = UIImageView()
        imageView.backgroundColor = UIColor.white
        return imageView
    }()
    
    lazy var nameLabel: UILabel = {
        let label = UILabel()
        label.font = UIFont.PingFangSC(size: 14)
        label.text = "title"
        label.textAlignment = .center
        label.textColor = UIColor(red: 48, green: 48, blue: 48, alpha: 1.0)
        return label
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.setupSubViews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setupSubViews() {
        self.contentView.backgroundColor = UIColor(red: 247, green: 247, blue: 247, alpha: 247)
        
        self.contentView.addSubview(thumbnail)
        self.contentView.addSubview(nameLabel)
        
        nameLabel.snp.makeConstraints { (maker) in
            maker.leading.equalTo(8)
            maker.trailing.equalTo(-8)
            maker.height.equalTo(15)
            maker.bottom.equalTo(-8)
        }
        
        thumbnail.snp.makeConstraints { (maker) in
            maker.leading.equalTo(14)
            maker.trailing.equalTo(-14)
            maker.top.equalTo(14)
            maker.height.equalTo(thumbnail.snp.width)
        }
    }
}

// MARK: InterestedViewController

class InterestedViewController: UIViewController {

    let itemWidth = floor((UIScreen.main.bounds.size.width - CGFloat(25))/CGFloat(4.0))
    
    lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .vertical
        let collection = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
        collection.bounces = true
        collection.backgroundColor = UIColor.white
        collection.delegate = self
        collection.dataSource = self
        return collection
    }()
    
    
    // MARK: Life cycle
    override func viewDidLoad() {
        super.viewDidLoad()
        self.setupSubViews()
    }
}


//MARK: - Assistant
extension InterestedViewController {
    func setupSubViews() {
        self.view.backgroundColor = UIColor.white
        self.navigationItem.title = "CollectionView 演示"

        self.view.addSubview(collectionView)
        collectionView.register(InterCell.self, forCellWithReuseIdentifier: CellIdentifier)
      
        collectionView.snp.makeConstraints { (maker) in
            maker.leading.trailing.equalTo(0)
            maker.top.equalTo(8)
            maker.bottom.equalTo(-kSafeAreaBottomInset)
        }
    }
}

// MARK: UICollectionViewDataSource
extension InterestedViewController: UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return  1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 36
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: CellIdentifier, for: indexPath) as! InterCell

        return cell
    }
}

// MARK: UICollectionViewDelegate
extension InterestedViewController: UICollectionViewDelegate {
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        collectionView.deselectItem(at: indexPath, animated: true)
    }
}


// MARK: UICollectionViewDelegateFlowLayout
extension InterestedViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        
        return CGSize(width: itemWidth, height: itemWidth+CGFloat(20))
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 8, left: 5, bottom: 8, right: 5)
    }
    
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 5
    }
    
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }
}