如何在不同的数据源中使用多个数据模型？

Question

目前，我在尝试在应用程序中开发搜索视图时遇到了困难。我尝试将集合视图放置在表视图单元格中，并使用传统的集合视图数据源委托（行的单元格等），但是这些实现在现代应用程序中似乎都远非最佳。我们的应用程序使用“朋友”、“用户”和“场所”三个模型。

我们已经成功使用 Diffable 数据源和组合布局将其中一个模型填充到搜索视图中，但是当我尝试添加其他模型时，出现以下错误：

""*** 由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“无效参数不满足：部分！= NSNotFound”因未捕获的 NSException 类型异常而终止""

这是 SearchViewController

import UIKit

fileprivate typealias DataSource  = UICollectionViewDiffableDataSource<Section, SearchV2VC.DataType>
fileprivate typealias SourceSnapshot = NSDiffableDataSourceSnapshot<Section, SearchV2VC.DataType>

class SearchV2VC: UIViewController {
    
    
    var collectionView: UICollectionView! = nil
    private var dataSource: DataSource!
    var friendData = [FollowingInfo]()
    var userData = [FriendInfo]()
    var venueData = [Venue]()
   
    override func viewDidLoad() {
        super.viewDidLoad()
        
        configureHierarchy()
        configureDataSource()
        
        
    }
   
    private func firstLayoutSection() -> NSCollectionLayoutSection {

        let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .fractionalHeight(0.5))

        let item = NSCollectionLayoutItem(layoutSize: itemSize)
        item.contentInsets.bottom = 15

        let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.9), heightDimension: .fractionalWidth(0.5))

        let group = NSCollectionLayoutGroup.vertical(layoutSize: groupSize, subitems: [item])
        group.contentInsets = .init(top: 0, leading: 15, bottom: 0, trailing: 2)

        let section = NSCollectionLayoutSection(group: group)

        //section.orthogonalScrollingBehavior = .groupPaging
        section.orthogonalScrollingBehavior = .none



        return section
    }
    private func secondLayoutSection() -> NSCollectionLayoutSection {

        let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .fractionalHeight(0.5))

        let item = NSCollectionLayoutItem(layoutSize: itemSize)
        item.contentInsets.bottom = 15

        let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.9), heightDimension: .fractionalWidth(0.5))

        let group = NSCollectionLayoutGroup.vertical(layoutSize: groupSize, subitems: [item])
        group.contentInsets = .init(top: 0, leading: 15, bottom: 0, trailing: 2)

        let section = NSCollectionLayoutSection(group: group)

        //section.orthogonalScrollingBehavior = .groupPaging
        section.orthogonalScrollingBehavior = .none



        return section
    }

    private func thirdLayoutSection() -> NSCollectionLayoutSection {

        let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .fractionalHeight(2))

        let item = NSCollectionLayoutItem(layoutSize: itemSize)
        item.contentInsets.bottom = 15

        let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.35), heightDimension: .fractionalWidth(0.35))

        let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, subitems: [item])
        group.contentInsets = .init(top: 0, leading: 15, bottom: 0, trailing: 0)

        let section = NSCollectionLayoutSection(group: group)

        navigationItem.title = "You a Bitch"

        section.orthogonalScrollingBehavior = .continuous

        return section
    }
}
extension SearchV2VC {
private func createLayout() -> UICollectionViewCompositionalLayout {

    return UICollectionViewCompositionalLayout { (sectionNumber, env) -> NSCollectionLayoutSection? in

     switch sectionNumber {

     case 0: return self.firstLayoutSection()
     case 1: return self.secondLayoutSection()
     default: return self.thirdLayoutSection()

     }
   }
}
}
    //MARK: - UICollectionViewDataSource Methods


extension SearchV2VC {
    private func configureHierarchy() {
        //collectionView.delegate = self
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: createLayout())
        collectionView.delegate = self
        collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        collectionView.backgroundColor = .white
        
        collectionView.register(UserCell.self, forCellWithReuseIdentifier: UserCell.reuseIdentifier)
        collectionView.register(FriendCell.self, forCellWithReuseIdentifier: FriendCell.reuseIdentifier)
        collectionView.register(VenueCell.self, forCellWithReuseIdentifier: VenueCell.reuseIdentifier)
        view.addSubview(collectionView)
        
        
     
    }
}
extension SearchV2VC {
    

    func configureDataSource(){
        
        dataSource = DataSource(collectionView: collectionView, cellProvider: { (collectionView, index, friend) -> UICollectionViewCell in
            
            switch friend{
            case .user(let user):
                guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: UserCell.reuseIdentifier, for: index) as? UserCell else {fatalError("Couldn't Create New Cell")}
                cell.viewModel = UserCellViewModel(user: user)
                return cell
            
            case .friend(let friend):
                guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: FriendCell.reuseIdentifier, for: index) as? FriendCell else {fatalError("Couldn't Create New Cell")}
                cell.viewModel = FriendCellViewModel(user: friend)
                return cell
            case .venue(let venue):
                guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: VenueCell.reuseIdentifier, for: index) as? VenueCell else {fatalError("Couldn't Create New Cell")}
                cell.viewModel = VenueCellViewModel(venue: venue)
                return cell
            }
            
            
        })
       
        dataSource.apply(snapshotForCurrentState(), animatingDifferences: false)
        
    }
            
        



func snapshotForCurrentState() -> NSDiffableDataSourceSnapshot<Section, DataType>{
    var snapshot = NSDiffableDataSourceSnapshot<Section, DataType>()
    snapshot.appendSections(Section.allSections)

    let userItems = userData.map { DataType.user($0) }
    snapshot.appendItems(userItems, toSection: Section.users)

    let friendItems = friendData.map { DataType.friend($0) }
    snapshot.appendItems(friendItems, toSection: Section.friends)

    let venueItems = venueData.map { DataType.venue($0) }
    snapshot.appendItems(venueItems, toSection: Section.venue)
    return snapshot
    }
}
extension SearchV2VC: UICollectionViewDelegate  {
    

    enum DataType: Hashable {
        case user(FriendInfo)
        
        case friend(FollowingInfo)
        
        case venue(Venue)
    }
    
     func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
         collectionView.deselectItem(at: indexPath, animated: true)
         guard let user = dataSource.itemIdentifier(for: indexPath) else { return }
        print(user)
     }
    
}

这就是我们的模型的样子：

import Foundation
import Firebase
import Mapbox

struct Venue: Hashable {
    
    static func == (lhs: Venue, rhs: Venue) -> Bool {
        lhs.venID == rhs.venID
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(venID)
    }
    
    var venID: String?
    var latitude: Double?
    var longitude: Double?
    var name: String?
    var description: String?
    var image: String?
    var address: String?

}

struct FriendInfo: Hashable {
    
    static func == (lhs: FriendInfo, rhs: FriendInfo) -> Bool {
        lhs.userID == rhs.userID
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(userID)
    }
    
    var displayName: String?
    var userID: String?
    var userName: String?
    var providerID: String?
    var profileImageURL: String?
    var isFriend = false
    var stats: UserStats?
    var isCurrentUser: Bool { return Auth.auth().currentUser?.uid == providerID }
}

struct FollowingInfo: Hashable {
    
    static func == (lhs: FollowingInfo, rhs: FollowingInfo) -> Bool {
        lhs.userID == rhs.userID
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(userID)
    }
    
    var displayName: String?
    var userID: String?
    var profileURL: String?
    var userName: String?
}

最后，这是我们使用的自定义部分类，而不是控制器中通常的“枚举部分”，这很可能是问题所在：

import UIKit

struct Section: Hashable {
    var id = UUID()
    
    var title: String
    var data: [Any]
    
    init(title: String, data: [Any]) {
        self.title = title
        self.data = data
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
    }
    
    static func == (lhs: Section, rhs: Section) -> Bool {
        lhs.id == rhs.id
    }
    
}

extension Section {
    static var allSections: [Section] = [
        Section(title: "Users", data: [FriendInfo]()),
        Section(title: "Friends", data: [FollowingInfo]()),
        Section(title: "Venue", data: [Venue]())
    ]
}

extension Section {
    static var users: Section = 
    Section(title: "Users", data: [FriendInfo]())
}

extension Section {
    static var friends: Section =
    Section(title: "Friends", data: [FollowingInfo]())
}

extension Section {
    static var venue: Section =
    Section(title: "Venue", data: [Venue]())
}

最后，我应该提到我们通过对 Firebase 的 API 调用使用完全不同的数据设置这 3 个模型。（数据在应用程序中的其他地方按预期运行）集合视图单元格正在利用视图模型，因此在视图控制器中看到“cell.viewModel = ...”。

几天来我一直在努力让这个功能按预期运行。我观看了 Apple 的每个视频，彻底检查了所有示例项目，并访问了 google 提供的有关该主题的几乎每个链接。

这是我的第一个堆栈问题，因此如果我错过了任何重要信息，我深表歉意。当然有人已经实现了类似的设计，我愿意接受任何实现这一目标的方法。谢谢！

Answer 1

I actually found your post while trying to figure this out for myself, and just got it to work. You're definitely on the right track by using enums. I'm sorry I can't tell you exactly what that error means, but here is the gist of what worked for me. I have only two different models (Event and Filter), but obviously it could be expanded to work with 3+.

typealias EventsDataSource = UICollectionViewDiffableDataSource<Section, Item>
typealias EventsSnapshot = NSDiffableDataSourceSnapshot<Section, Item>

struct Filter {
    let text: String
}

struct Event {
    let description: String
    let startTime: Date
    let endTime: Date
}

enum Item: Hashable {
    case filter(Filter)
    case event(Event)
}

struct Section: Hashable {
    let items: [Item]
    let title: String?
}

Donny Wals has a particularly good Diffable Datasources article.

(And if you're looking to integrate Core Data into your Diffable Datasource, Julian Schiavo's article is immensely helpful too.)