我目前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” 以 NSException"" 类型的未捕获异常终止
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?
}
最后这里是我们使用的自定义部分类，而不是位于控制器中的通常的“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！
实际上，我在尝试自己解决这个问题时找到了你的帖子，并且刚刚开始工作。使用枚举肯定是走在正确的道路上。很抱歉，我无法确切地告诉您该错误的含义，但这是对我有用的要点。我只有两个不同的模型（事件和过滤器），但显然它可以扩展到 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 有一篇特别好的 Diffable Datasources 文章。
（如果您希望将核心数据集成到 Diffable 数据源中，Julian Schiavo 的文章 也非常有帮助。）
将 ItemIdentifier 实例添加到尚未添加到快照的 SectionIdentifier 实例时，您会收到此错误
Invalid parameter not satisfying: section != NSNotFound因此在做
snapshot.appendSections([...])之前不要忘记做
snapshot.appendItems([...], toSection:...)
对我来说，使用多个模型的最佳方法是将它们转换为可哈希的。
型号：
struct ModelA: Hashable {
let title: String
}
struct ModelB: Hashable {
let image: UIImage
}
enum Section {
case a
case b
}
UICollectionViewDiffableDataSource：
let dataSource = UICollectionViewDiffableDataSource<Section, AnyHashable>(collectionView: collectionView) { collectionView, indexPath, item in
switch item {
case let model as ModelA:
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellA", for: indexPath) as! CellA
cell.configure(with: model)
return cell
case let model as ModelB:
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellB", for: indexPath) as! CellB
cell.configure(with: model)
return cell
default:
fatalError("Unknown item type")
}
}
用数据填充 UICollectionViewDiffableDataSource：
var snapshot = NSDiffableDataSourceSnapshot<Section, AnyHashable>()
snapshot.appendSections([.a, .b])
snapshot.appendItems([ModelA(title: "Item 1"), ModelA(title: "Item 2")], toSection: .a)
snapshot.appendItems([ModelB(image: UIImage(named: "image1")), ModelB(image: UIImage(named: "image2"))], toSection: .b)
dataSource.apply(snapshot, animatingDifferences: false)
UICollectionViewDelegate 方法：
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
guard let item = dataSource.itemIdentifier(for: indexPath) else { return }
switch item {
case let model as ModelA:
print("Selected item A with title: \(model.title)")
case let model as ModelB:
print("Selected item B with image: \(model.image)")
default:
break
}
}