消息显示在错误的一侧且 size/content 不正确 (MessageKit)
Messages showing up on wrong side and with incorrect size/content (MessageKit)
我正在开发的应用程序中使用 MessageKit 作为聊天功能，在向 messagesCollectionView 中插入部分时遇到了一个奇怪的布局错误。打开对话时，线程会从缓存中正确加载，但是当加载下一页消息（数据源已分页）并且消息在批量更新中添加到 UICollectionView 时（请参见下面的代码），消息出错，出现在错误的索引处、错误的大小、错误的一侧，偶尔还会出现错误的文本。
我尝试过更改添加消息的方式，但我尝试过的所有方式都导致了这种情况...该应用程序的先前版本通过以下方式完全重新加载了 messagesCollectionView reloadData()，但即使使用该实现，这个错误在第一次打开线程时发生（看似 仅在 重新加载数据源并且集合视图一直滚动到底部。我对 MessageKit 和 UICollectionView 的了解还不够，无法解决这个问题，希望对他们的复杂性有更好了解的人会发现这个错误！
//
// ThreadDetailViewController.swift
// --
//
// Created by Jai Smith on 7/18/19.
// Copyright © 2019 --. All rights reserved.
//
import UIKit
import MessageKit
import InputBarAccessoryView
import Alamofire
import os.log
import Kingfisher
class ThreadDetailViewController: MessagesViewController {
// MARK: Properties
var thread: MessageThread!
var messages: Int = 0
var reachedEnd: Bool = false
var loadLock: Bool = false
var page: PageManager?
var scrollingUp: Bool = false
var shouldFetchNextPage: Bool = false
var messagesToAdd: Int?
var insertingSections: Bool = false
// MARK: Overrides
override func viewDidLoad() {
super.viewDidLoad()
// set title
self.title = thread.title
// add notification observers
NotificationCenter.default.addObserver(self, selector: #selector(receivedMessage), name: Notification.Name("receivedMessage"), object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(socketStateChanged), name: Notification.Name("sockState"), object: nil)
// scroll to bottom when typing
self.scrollsToBottomOnKeyboardBeginsEditing = true
// set delegate/source
messagesCollectionView.messagesDisplayDelegate = self
messagesCollectionView.messagesDataSource = self
messagesCollectionView.messagesLayoutDelegate = self
messagesCollectionView.contentInset = UIEdgeInsets(top: 2.5, left: 0, bottom: 2.5, right: 0)
messageInputBar = CustomInputBar()
messageInputBar.delegate = self
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
// start scrolled all the way to the bottom of already loaded messages
messages = thread.messages.count
messagesCollectionView.reloadData()
messagesCollectionView.scrollToBottom(animated: false)
// load messages
self.loadMessages()
}
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if indexPath.section == 0, let amount = messagesToAdd {
animateMessageInsertion(amount: amount)
self.messagesToAdd = nil
}
}
// MARK: UIScrollViewDelegate
func scrollViewDidScroll(_ scrollView: UIScrollView) {
scrollingUp = scrollView.panGestureRecognizer.translation(in: scrollView.superview).y > 0
}
// MARK: Navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
switch segue.identifier {
case "ProfileDetail":
if let profileTableViewController = segue.destination as? ProfileTableViewController {
profileTableViewController.user = getConversants().first
}
default:
fatalError("Unexpected Segue Identifier: \(segue.identifier ?? "nil")")
}
}
// MARK: Public Methods
@objc func socketStateChanged(_ notification: Notification) {
if let status = notification.object as? Int {
if status == 0 {
os_log("Connecting...", log: OSLog.default, type: .debug)
} else if status == 1 {
// enable send button if text is entered
if !self.messageInputBar.inputTextView.text.isEmpty {
self.messageInputBar.sendButton.isEnabled = true
}
}
}
}
@objc func receivedMessage(_ notification: Notification) {
if let message = notification.object as? Message {
self.thread.messages.append(message)
self.messages += 1
self.messagesCollectionView.insertSections([self.thread.messages.count - 1])
self.messagesCollectionView.scrollToBottom(animated: true)
}
}
@objc func loadMessages() {
// lock (prevent this method from being called twice)
self.loadLock = true
Credentials.shared.session.request(API.shared.messaging.history, method: .get, parameters: ["hash": thread.hash], encoding: URLEncoding.default)
.validate(statusCode: [200])
.validate(contentType: ["application/json"])
.responseJSON { response in
defer {
// unlock
self.loadLock = false
if self.shouldFetchNextPage {
self.loadMoreMessages()
}
}
switch response.result {
case .success:
guard let data = response.data, let page = try? JSONDecoder().decode(PageManager.self, from: data) else {
os_log("Error deserializing PageManager for ThreadDetail", log: OSLog.default, type: .error)
return
}
// decode messages
var messages = [Message]()
while !page.results.isAtEnd {
do {
let message = try page.results.decode(Message.self)
messages.append(message)
} catch {
os_log("Error deserializing Message", log: OSLog.default, type: .error)
_ = try? page.results.decode(AnyCodable.self)
}
}
self.page = page
self.thread.messages = messages.reversed()
self.messages = self.thread.messages.count
self.messagesCollectionView.reloadData()
self.messagesCollectionView.scrollToBottom(animated: false)
case .failure:
os_log("Error loading messages for thread", log: OSLog.default, type: .error)
}
}
}
// MARK: Private Methods
private func getConversants() -> [User] {
var conversants = [User]()
for user in thread.participants.filter({ user in return user.id != Credentials.shared.user.id }) {
conversants.append(user)
}
if conversants.isEmpty {
conversants.append(Credentials.shared.user)
}
return conversants
}
//
private func animateMessageInsertion(amount: Int) {
guard !insertingSections else {
return
}
insertingSections = true
let contentHeight = self.messagesCollectionView.contentSize.height
let offsetY = self.messagesCollectionView.contentOffset.y
let bottomOffset = contentHeight - offsetY
CATransaction.begin()
CATransaction.setDisableActions(true)
self.messagesCollectionView.performBatchUpdates({
if amount > 0 {
self.messages += amount
self.messagesCollectionView.insertSections(IndexSet(integersIn: self.thread.messages.count - amount..<self.thread.messages.count))
}
}, completion: { finished in
defer {
self.insertingSections = false
}
os_log("Finished inserting new messages, animating...", log: OSLog.default, type: .debug)
self.messagesCollectionView.contentOffset = CGPoint(x: 0, y: self.messagesCollectionView.contentSize.height - bottomOffset)
CATransaction.commit()
})
}
private func loadMoreMessages() {
guard !loadLock else {
return
}
guard let page = page else {
shouldFetchNextPage = true
return
}
guard page.next != nil else {
return
}
loadLock = true
page.getNextPage(completion: { page in
defer {
self.loadLock = false
}
guard let page = page else {
os_log("Error loading next page", log: OSLog.default, type: .error)
return
}
// decode new messages
var messages = [Message]()
while !page.results.isAtEnd {
do {
let message = try page.results.decode(Message.self)
messages.append(message)
} catch {
os_log("Error deserializing Message", log: OSLog.default, type: .error)
_ = try? page.results.decode(AnyCodable.self)
}
}
// append to messages array
self.thread.messages.insert(contentsOf: messages.reversed(), at: 0)
self.page = page
// queue messages to be added
self.messagesToAdd = messages.count
// trigger insertion if top message is already visible
if self.messagesCollectionView.indexPathsForVisibleItems.contains(where: { indexPath in return indexPath.section == 0 }), let amount = self.messagesToAdd {
self.animateMessageInsertion(amount: amount)
self.messagesToAdd = nil
}
})
}
}
// MARK: Extensions
extension ThreadDetailViewController: MessagesDataSource {
func currentSender() -> SenderType {
return Credentials.shared.user
}
func messageForItem(at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageType {
// check if more messages should be loaded
if !loadLock, indexPath.section < 4, page == nil ? true : scrollingUp {
loadMoreMessages()
loadLock = true
}
return thread.messages[indexPath.section]
}
func numberOfSections(in messagesCollectionView: MessagesCollectionView) -> Int {
return messages
}
func cellTopLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section - 1 >= 0 {
let prevMessage = self.thread.messages[indexPath.section - 1]
if message.sentDate.timeIntervalSince(prevMessage.sentDate).isLess(than: 24 * 3600.0) {
return nil
}
}
return NSAttributedString(string: message.sentDate.displayFormatDate(), attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption1)])
}
func messageTopLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section - 1 >= 0 {
let prevMessage = self.thread.messages[indexPath.section - 1]
if prevMessage.sender.senderId == message.sender.senderId && cellTopLabelAttributedText(for: message, at: indexPath) == nil {
return nil
}
}
return NSAttributedString(string: message.sender.displayName, attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption1)])
}
func messageBottomLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section + 1 < numberOfSections(in: messagesCollectionView) {
let nextMessage = self.thread.messages[indexPath.section + 1]
if nextMessage.sentDate.timeIntervalSince(message.sentDate).isLessThanOrEqualTo(3600.0) {
return nil
}
}
return NSAttributedString(string: message.sentDate.displayFormatTime(), attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption2)])
}
}
extension ThreadDetailViewController: InputBarAccessoryViewDelegate {
func inputBar(_ inputBar: InputBarAccessoryView, textViewTextDidChangeTo text: String) {
if !SocketManager.shared.sock.isConnected {
inputBar.sendButton.isEnabled = false
}
}
func inputBar(_ inputBar: InputBarAccessoryView, didPressSendButtonWith text: String) {
inputBar.inputTextView.text = ""
SocketManager.shared.sendMessage(text, hash: thread.hash)
}
}
extension ThreadDetailViewController: MessagesLayoutDelegate {
func messagePadding(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> UIEdgeInsets {
return UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20)
}
func messageTopLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return messageTopLabelAttributedText(for: message, at: indexPath)?.size().height ?? 0
}
func messageBottomLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return messageBottomLabelAttributedText(for: message, at: indexPath)?.size().height ?? 0
}
func cellTopLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return cellTopLabelAttributedText(for: message, at: indexPath)?.size().height ?? -5
}
}
extension ThreadDetailViewController: MessagesDisplayDelegate {
func configureAvatarView(_ avatarView: AvatarView, for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) {
if let index = UserList.index, let id = (message.sender as? User)?.id, let avatarURL = index[id]?.avatar {
var image: UIImage = UIImage(named: "placeholder")!
KingfisherManager.shared.retrieveImage(with: avatarURL, completionHandler: { result in
switch result {
case .success:
do {
image = try result.get().image
messagesCollectionView.reloadItems(at: [indexPath])
} catch {
os_log("Couldn't retrieve image with Kingfisher", log: OSLog.default, type: .error)
}
case .failure:
os_log("Failed to load profile image for %@ in Message", log: OSLog.default, type: .error, index[id]?.displayName ?? "nil")
}
})
var initials: String
if let user = index[id] {
initials = "\(user.firstName.capitalized.first ?? " ")\(user.lastName.capitalized.first ?? " ")"
} else {
initials = "nil"
}
avatarView.set(avatar: Avatar(image: image, initials: initials))
} else {
avatarView.set(avatar: Avatar(image: UIImage(named: "placeholder"), initials: "\(message.sender.displayName.first ?? "?")"))
}
}
}
这里的问题应该相当明显，但是标记为 'Jai' 的消息应该出现在左侧，消息气泡应该包含它们包含的文本。
更新： 似乎 MessageKit 正在计算消息大小和消息的发件人在数据源中的一个索引，然后从正确的索引中获取文本index...虽然不知道发生了什么。
在使用不同的策略将部分插入 UICollectionView 几个小时后，在没有出现这种错误行为的情况下，我将 UICollectionView 颠倒过来，现在在底部添加部分，效果很好。我最初避免使用这种方法是因为害怕引入大消息线程的性能问题（我在几个论坛上读到过），但到目前为止还没有 运行 遇到任何这样的问题。如果有人遇到与我上面描述的问题类似的问题并试图将部分插入 UICollectionView 的顶部，我建议像我一样翻转 UICollectionView。它使整个过程变得更加容易。
（对于那些好奇的人，上述问题是由于更新数据源并将部分插入 UICollectionView，导致单元格重新加载，并在此过程中从数据源中的错误索引获取数据...我确定有一种方法可以纠正这个问题，但如果翻转 UICollectionView 与你的应用程序设计一起工作，它会更容易，也不会那么麻烦）
我正在开发的应用程序中使用 MessageKit 作为聊天功能，在向 messagesCollectionView 中插入部分时遇到了一个奇怪的布局错误。打开对话时，线程会从缓存中正确加载，但是当加载下一页消息（数据源已分页）并且消息在批量更新中添加到 UICollectionView 时（请参见下面的代码），消息出错，出现在错误的索引处、错误的大小、错误的一侧，偶尔还会出现错误的文本。
我尝试过更改添加消息的方式，但我尝试过的所有方式都导致了这种情况...该应用程序的先前版本通过以下方式完全重新加载了 messagesCollectionView reloadData()，但即使使用该实现，这个错误在第一次打开线程时发生（看似 仅在 重新加载数据源并且集合视图一直滚动到底部。我对 MessageKit 和 UICollectionView 的了解还不够，无法解决这个问题，希望对他们的复杂性有更好了解的人会发现这个错误！
//
// ThreadDetailViewController.swift
// --
//
// Created by Jai Smith on 7/18/19.
// Copyright © 2019 --. All rights reserved.
//
import UIKit
import MessageKit
import InputBarAccessoryView
import Alamofire
import os.log
import Kingfisher
class ThreadDetailViewController: MessagesViewController {
// MARK: Properties
var thread: MessageThread!
var messages: Int = 0
var reachedEnd: Bool = false
var loadLock: Bool = false
var page: PageManager?
var scrollingUp: Bool = false
var shouldFetchNextPage: Bool = false
var messagesToAdd: Int?
var insertingSections: Bool = false
// MARK: Overrides
override func viewDidLoad() {
super.viewDidLoad()
// set title
self.title = thread.title
// add notification observers
NotificationCenter.default.addObserver(self, selector: #selector(receivedMessage), name: Notification.Name("receivedMessage"), object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(socketStateChanged), name: Notification.Name("sockState"), object: nil)
// scroll to bottom when typing
self.scrollsToBottomOnKeyboardBeginsEditing = true
// set delegate/source
messagesCollectionView.messagesDisplayDelegate = self
messagesCollectionView.messagesDataSource = self
messagesCollectionView.messagesLayoutDelegate = self
messagesCollectionView.contentInset = UIEdgeInsets(top: 2.5, left: 0, bottom: 2.5, right: 0)
messageInputBar = CustomInputBar()
messageInputBar.delegate = self
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
// start scrolled all the way to the bottom of already loaded messages
messages = thread.messages.count
messagesCollectionView.reloadData()
messagesCollectionView.scrollToBottom(animated: false)
// load messages
self.loadMessages()
}
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if indexPath.section == 0, let amount = messagesToAdd {
animateMessageInsertion(amount: amount)
self.messagesToAdd = nil
}
}
// MARK: UIScrollViewDelegate
func scrollViewDidScroll(_ scrollView: UIScrollView) {
scrollingUp = scrollView.panGestureRecognizer.translation(in: scrollView.superview).y > 0
}
// MARK: Navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
switch segue.identifier {
case "ProfileDetail":
if let profileTableViewController = segue.destination as? ProfileTableViewController {
profileTableViewController.user = getConversants().first
}
default:
fatalError("Unexpected Segue Identifier: \(segue.identifier ?? "nil")")
}
}
// MARK: Public Methods
@objc func socketStateChanged(_ notification: Notification) {
if let status = notification.object as? Int {
if status == 0 {
os_log("Connecting...", log: OSLog.default, type: .debug)
} else if status == 1 {
// enable send button if text is entered
if !self.messageInputBar.inputTextView.text.isEmpty {
self.messageInputBar.sendButton.isEnabled = true
}
}
}
}
@objc func receivedMessage(_ notification: Notification) {
if let message = notification.object as? Message {
self.thread.messages.append(message)
self.messages += 1
self.messagesCollectionView.insertSections([self.thread.messages.count - 1])
self.messagesCollectionView.scrollToBottom(animated: true)
}
}
@objc func loadMessages() {
// lock (prevent this method from being called twice)
self.loadLock = true
Credentials.shared.session.request(API.shared.messaging.history, method: .get, parameters: ["hash": thread.hash], encoding: URLEncoding.default)
.validate(statusCode: [200])
.validate(contentType: ["application/json"])
.responseJSON { response in
defer {
// unlock
self.loadLock = false
if self.shouldFetchNextPage {
self.loadMoreMessages()
}
}
switch response.result {
case .success:
guard let data = response.data, let page = try? JSONDecoder().decode(PageManager.self, from: data) else {
os_log("Error deserializing PageManager for ThreadDetail", log: OSLog.default, type: .error)
return
}
// decode messages
var messages = [Message]()
while !page.results.isAtEnd {
do {
let message = try page.results.decode(Message.self)
messages.append(message)
} catch {
os_log("Error deserializing Message", log: OSLog.default, type: .error)
_ = try? page.results.decode(AnyCodable.self)
}
}
self.page = page
self.thread.messages = messages.reversed()
self.messages = self.thread.messages.count
self.messagesCollectionView.reloadData()
self.messagesCollectionView.scrollToBottom(animated: false)
case .failure:
os_log("Error loading messages for thread", log: OSLog.default, type: .error)
}
}
}
// MARK: Private Methods
private func getConversants() -> [User] {
var conversants = [User]()
for user in thread.participants.filter({ user in return user.id != Credentials.shared.user.id }) {
conversants.append(user)
}
if conversants.isEmpty {
conversants.append(Credentials.shared.user)
}
return conversants
}
//
private func animateMessageInsertion(amount: Int) {
guard !insertingSections else {
return
}
insertingSections = true
let contentHeight = self.messagesCollectionView.contentSize.height
let offsetY = self.messagesCollectionView.contentOffset.y
let bottomOffset = contentHeight - offsetY
CATransaction.begin()
CATransaction.setDisableActions(true)
self.messagesCollectionView.performBatchUpdates({
if amount > 0 {
self.messages += amount
self.messagesCollectionView.insertSections(IndexSet(integersIn: self.thread.messages.count - amount..<self.thread.messages.count))
}
}, completion: { finished in
defer {
self.insertingSections = false
}
os_log("Finished inserting new messages, animating...", log: OSLog.default, type: .debug)
self.messagesCollectionView.contentOffset = CGPoint(x: 0, y: self.messagesCollectionView.contentSize.height - bottomOffset)
CATransaction.commit()
})
}
private func loadMoreMessages() {
guard !loadLock else {
return
}
guard let page = page else {
shouldFetchNextPage = true
return
}
guard page.next != nil else {
return
}
loadLock = true
page.getNextPage(completion: { page in
defer {
self.loadLock = false
}
guard let page = page else {
os_log("Error loading next page", log: OSLog.default, type: .error)
return
}
// decode new messages
var messages = [Message]()
while !page.results.isAtEnd {
do {
let message = try page.results.decode(Message.self)
messages.append(message)
} catch {
os_log("Error deserializing Message", log: OSLog.default, type: .error)
_ = try? page.results.decode(AnyCodable.self)
}
}
// append to messages array
self.thread.messages.insert(contentsOf: messages.reversed(), at: 0)
self.page = page
// queue messages to be added
self.messagesToAdd = messages.count
// trigger insertion if top message is already visible
if self.messagesCollectionView.indexPathsForVisibleItems.contains(where: { indexPath in return indexPath.section == 0 }), let amount = self.messagesToAdd {
self.animateMessageInsertion(amount: amount)
self.messagesToAdd = nil
}
})
}
}
// MARK: Extensions
extension ThreadDetailViewController: MessagesDataSource {
func currentSender() -> SenderType {
return Credentials.shared.user
}
func messageForItem(at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageType {
// check if more messages should be loaded
if !loadLock, indexPath.section < 4, page == nil ? true : scrollingUp {
loadMoreMessages()
loadLock = true
}
return thread.messages[indexPath.section]
}
func numberOfSections(in messagesCollectionView: MessagesCollectionView) -> Int {
return messages
}
func cellTopLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section - 1 >= 0 {
let prevMessage = self.thread.messages[indexPath.section - 1]
if message.sentDate.timeIntervalSince(prevMessage.sentDate).isLess(than: 24 * 3600.0) {
return nil
}
}
return NSAttributedString(string: message.sentDate.displayFormatDate(), attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption1)])
}
func messageTopLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section - 1 >= 0 {
let prevMessage = self.thread.messages[indexPath.section - 1]
if prevMessage.sender.senderId == message.sender.senderId && cellTopLabelAttributedText(for: message, at: indexPath) == nil {
return nil
}
}
return NSAttributedString(string: message.sender.displayName, attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption1)])
}
func messageBottomLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
if indexPath.section + 1 < numberOfSections(in: messagesCollectionView) {
let nextMessage = self.thread.messages[indexPath.section + 1]
if nextMessage.sentDate.timeIntervalSince(message.sentDate).isLessThanOrEqualTo(3600.0) {
return nil
}
}
return NSAttributedString(string: message.sentDate.displayFormatTime(), attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption2)])
}
}
extension ThreadDetailViewController: InputBarAccessoryViewDelegate {
func inputBar(_ inputBar: InputBarAccessoryView, textViewTextDidChangeTo text: String) {
if !SocketManager.shared.sock.isConnected {
inputBar.sendButton.isEnabled = false
}
}
func inputBar(_ inputBar: InputBarAccessoryView, didPressSendButtonWith text: String) {
inputBar.inputTextView.text = ""
SocketManager.shared.sendMessage(text, hash: thread.hash)
}
}
extension ThreadDetailViewController: MessagesLayoutDelegate {
func messagePadding(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> UIEdgeInsets {
return UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20)
}
func messageTopLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return messageTopLabelAttributedText(for: message, at: indexPath)?.size().height ?? 0
}
func messageBottomLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return messageBottomLabelAttributedText(for: message, at: indexPath)?.size().height ?? 0
}
func cellTopLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
return cellTopLabelAttributedText(for: message, at: indexPath)?.size().height ?? -5
}
}
extension ThreadDetailViewController: MessagesDisplayDelegate {
func configureAvatarView(_ avatarView: AvatarView, for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) {
if let index = UserList.index, let id = (message.sender as? User)?.id, let avatarURL = index[id]?.avatar {
var image: UIImage = UIImage(named: "placeholder")!
KingfisherManager.shared.retrieveImage(with: avatarURL, completionHandler: { result in
switch result {
case .success:
do {
image = try result.get().image
messagesCollectionView.reloadItems(at: [indexPath])
} catch {
os_log("Couldn't retrieve image with Kingfisher", log: OSLog.default, type: .error)
}
case .failure:
os_log("Failed to load profile image for %@ in Message", log: OSLog.default, type: .error, index[id]?.displayName ?? "nil")
}
})
var initials: String
if let user = index[id] {
initials = "\(user.firstName.capitalized.first ?? " ")\(user.lastName.capitalized.first ?? " ")"
} else {
initials = "nil"
}
avatarView.set(avatar: Avatar(image: image, initials: initials))
} else {
avatarView.set(avatar: Avatar(image: UIImage(named: "placeholder"), initials: "\(message.sender.displayName.first ?? "?")"))
}
}
}
这里的问题应该相当明显，但是标记为 'Jai' 的消息应该出现在左侧，消息气泡应该包含它们包含的文本。
更新： 似乎 MessageKit 正在计算消息大小和消息的发件人在数据源中的一个索引，然后从正确的索引中获取文本index...虽然不知道发生了什么。
在使用不同的策略将部分插入 UICollectionView 几个小时后，在没有出现这种错误行为的情况下，我将 UICollectionView 颠倒过来，现在在底部添加部分，效果很好。我最初避免使用这种方法是因为害怕引入大消息线程的性能问题（我在几个论坛上读到过），但到目前为止还没有 运行 遇到任何这样的问题。如果有人遇到与我上面描述的问题类似的问题并试图将部分插入 UICollectionView 的顶部，我建议像我一样翻转 UICollectionView。它使整个过程变得更加容易。
（对于那些好奇的人，上述问题是由于更新数据源并将部分插入 UICollectionView，导致单元格重新加载，并在此过程中从数据源中的错误索引获取数据...我确定有一种方法可以纠正这个问题，但如果翻转 UICollectionView 与你的应用程序设计一起工作，它会更容易，也不会那么麻烦）