我正在使用 UITableViewDataSourcePrefetching 进行分页。
这些值将从领域本地存储中获取。
我会得到一个对象数组。这些值将应用于现有的 UITableViewDiffableDataSource 数据源。
应用快照后，tableview 滚动到顶部。
我已经验证了我所有的 ChatMessage 对象都有唯一的 hashValues。
如何防止滚动？
链接到视频TableView_scroll_issue_video
鉴于我的代码片段
private func appendLocal(chats chatMessages: [ChatMessage]) {
var sections: [String] = chatMessages.map({ $0.chatDateTime.toString() })
sections.removeDuplicates()
guard !sections.isEmpty else { return }
var snapshot = dataSource.snapshot()
let chatSections = snapshot.sectionIdentifiers
sections.forEach { section in
let messages = chatMessages.filter({ $0.chatDateTime.toString() == section })
/// Checking the section is already exists in the dataSource
if let index = chatSections.firstIndex(of: section) {
let indexPath = IndexPath(row: 0, section: index)
/// Checking dataSource already have some messages inside the same section
/// If messages available then add the recieved messages to the top of existing messages
/// else only section is available so append all the messages to the section
if let item = dataSource.itemIdentifier(for: indexPath) {
snapshot.insertItems(messages, beforeItem: item)
} else {
snapshot.appendItems(messages, toSection: section)
}
} else if let firstSection = chatSections.first {
/// Newly receieved message's section not available in the dataSource
/// Add the section before existing section
/// Add the messages to the newly created section
snapshot.insertSections([section], beforeSection: firstSection)
snapshot.appendItems(messages, toSection: section)
} else {
/// There is no messages available append the new section and messages
snapshot.appendSections([section])
snapshot.appendItems(messages, toSection: section)
}
}
dataSource.apply(snapshot, animatingDifferences: false)
}