session-ios/Signal/src/ViewControllers/MessageDetailViewController.swift
sdkjfhsdkjhfsdlkjhfsdf 411de65b40 TODO: Show caption in details
TODO:
- [ ] layout is shite

// FREEBIE
2017-12-20 14:26:53 -06:00

730 lines
30 KiB
Swift

//
// Copyright (c) 2017 Open Whisper Systems. All rights reserved.
//
import Foundation
import SignalServiceKit
import SignalMessaging
@objc
enum MessageMetadataViewMode: UInt {
case focusOnMessage
case focusOnMetadata
}
class MessageDetailViewController: OWSViewController, UIScrollViewDelegate {
static let TAG = "[MessageDetailViewController]"
let TAG = "[MessageDetailViewController]"
// MARK: Properties
let contactsManager: OWSContactsManager
let databaseConnection: YapDatabaseConnection
let bubbleFactory = OWSMessagesBubbleImageFactory()
var bubbleView: UIView?
let mode: MessageMetadataViewMode
let viewItem: ConversationViewItem
var message: TSMessage
var mediaMessageView: MediaMessageView?
// See comments on updateTextLayout.
var messageTextView: UITextView?
var messageTextProxyView: UIView?
var messageTextTopConstraint: NSLayoutConstraint?
var messageTextHeightLayoutConstraint: NSLayoutConstraint?
var messageTextProxyViewHeightConstraint: NSLayoutConstraint?
var bubbleViewWidthConstraint: NSLayoutConstraint?
var scrollView: UIScrollView!
var contentView: UIView?
var attachment: TSAttachment?
var dataSource: DataSource?
var attachmentStream: TSAttachmentStream?
var messageBody: String?
// MARK: Initializers
@available(*, unavailable, message:"use other constructor instead.")
required init?(coder aDecoder: NSCoder) {
fatalError("\(#function) is unimplemented.")
}
required init(viewItem: ConversationViewItem, message: TSMessage, mode: MessageMetadataViewMode) {
self.contactsManager = Environment.current().contactsManager
self.viewItem = viewItem
self.message = message
self.mode = mode
self.databaseConnection = TSStorageManager.shared().newDatabaseConnection()!
super.init(nibName: nil, bundle: nil)
}
// MARK: View Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
self.databaseConnection.beginLongLivedReadTransaction()
updateDBConnectionAndMessageToLatest()
self.navigationItem.title = NSLocalizedString("MESSAGE_METADATA_VIEW_TITLE",
comment: "Title for the 'message metadata' view.")
createViews()
self.view.layoutIfNeeded()
NotificationCenter.default.addObserver(self,
selector: #selector(yapDatabaseModified),
name: NSNotification.Name.YapDatabaseModified,
object: nil)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
mediaMessageView?.viewWillAppear(animated)
updateTextLayout()
if mode == .focusOnMetadata {
if let bubbleView = self.bubbleView {
// Force layout.
view.setNeedsLayout()
view.layoutIfNeeded()
let contentHeight = scrollView.contentSize.height
let scrollViewHeight = scrollView.frame.size.height
guard contentHeight >= scrollViewHeight else {
// All content is visible within the scroll view. No need to offset.
return
}
// We want to include at least a little portion of the message, but scroll no farther than necessary.
let showAtLeast: CGFloat = 50
let bubbleViewBottom = bubbleView.superview!.convert(bubbleView.frame, to: scrollView).maxY
let maxOffset = bubbleViewBottom - showAtLeast
let lastPage = contentHeight - scrollViewHeight
let offset = CGPoint(x: 0, y: min(maxOffset, lastPage))
scrollView.setContentOffset(offset, animated: false)
}
}
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
mediaMessageView?.viewWillDisappear(animated)
}
// MARK: - Create Views
private func createViews() {
view.backgroundColor = UIColor.white
let scrollView = UIScrollView()
scrollView.delegate = self
self.scrollView = scrollView
view.addSubview(scrollView)
scrollView.autoPinWidthToSuperview(withMargin: 0)
scrollView.autoPin(toTopLayoutGuideOf: self, withInset: 0)
// See notes on how to use UIScrollView with iOS Auto Layout:
//
// https://developer.apple.com/library/content/releasenotes/General/RN-iOSSDK-6_0/
let contentView = UIView.container()
self.contentView = contentView
scrollView.addSubview(contentView)
contentView.autoPinLeadingToSuperview()
contentView.autoPinTrailingToSuperview()
contentView.autoPinEdge(toSuperviewEdge: .top)
contentView.autoPinEdge(toSuperviewEdge: .bottom)
scrollView.layoutMargins = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
let hasAttachment = message.attachmentIds.count > 0
if hasAttachment {
let footer = UIToolbar()
footer.barTintColor = UIColor.ows_materialBlue()
view.addSubview(footer)
footer.autoPinWidthToSuperview(withMargin: 0)
footer.autoPinEdge(.top, to: .bottom, of: scrollView)
footer.autoPin(toBottomLayoutGuideOf: self, withInset: 0)
footer.items = [
UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil),
UIBarButtonItem(barButtonSystemItem: .action, target: self, action: #selector(shareButtonPressed)),
UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
]
} else {
scrollView.autoPin(toBottomLayoutGuideOf: self, withInset: 0)
}
updateContent()
}
private func updateContent() {
guard let contentView = contentView else {
owsFail("\(TAG) Missing contentView")
return
}
// Remove any existing content views.
for subview in contentView.subviews {
subview.removeFromSuperview()
}
var rows = [UIView]()
let contactsManager = Environment.current().contactsManager!
let thread = message.thread
// Content
rows += contentRows()
// Sender?
if let incomingMessage = message as? TSIncomingMessage {
let senderId = incomingMessage.authorId
let senderName = contactsManager.contactOrProfileName(forPhoneIdentifier: senderId)
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_SENDER",
comment: "Label for the 'sender' field of the 'message metadata' view."),
value: senderName))
}
// Recipient(s)
if let outgoingMessage = message as? TSOutgoingMessage {
let isGroupThread = message.thread.isGroupThread()
let recipientStatusGroups: [MessageRecipientStatus] = [
.read,
.uploading,
.delivered,
.sent,
.sending,
.failed
]
for recipientStatusGroup in recipientStatusGroups {
var groupRows = [UIView]()
// TODO: It'd be nice to inset these dividers from the edge of the screen.
let addDivider = {
let divider = UIView()
divider.backgroundColor = UIColor(white: 0.9, alpha: 1.0)
divider.autoSetDimension(.height, toSize: 0.5)
groupRows.append(divider)
}
for recipientId in thread.recipientIdentifiers {
let (recipientStatus, statusMessage) = MessageRecipientStatusUtils.recipientStatusAndStatusMessage(outgoingMessage: outgoingMessage, recipientId: recipientId, referenceView: self.view)
guard recipientStatus == recipientStatusGroup else {
continue
}
if groupRows.count < 1 {
if isGroupThread {
groupRows.append(valueRow(name: string(for: recipientStatusGroup),
value: ""))
}
addDivider()
}
let cell = ContactTableViewCell()
cell.configure(withRecipientId: recipientId, contactsManager: self.contactsManager)
let statusLabel = UILabel()
statusLabel.text = statusMessage
statusLabel.textColor = UIColor.ows_darkGray()
statusLabel.font = UIFont.ows_footnote()
statusLabel.sizeToFit()
cell.accessoryView = statusLabel
cell.autoSetDimension(.height, toSize: ContactTableViewCell.rowHeight())
cell.setContentHuggingLow()
cell.isUserInteractionEnabled = false
groupRows.append(cell)
}
if groupRows.count > 0 {
addDivider()
let spacer = UIView()
spacer.autoSetDimension(.height, toSize: 10)
groupRows.append(spacer)
}
Logger.verbose("\(groupRows.count) rows for \(recipientStatusGroup)")
guard groupRows.count > 0 else {
continue
}
rows += groupRows
}
}
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_SENT_DATE_TIME",
comment: "Label for the 'sent date & time' field of the 'message metadata' view."),
value: DateUtil.formatPastTimestampRelativeToNow(message.timestamp)))
if message as? TSIncomingMessage != nil {
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_RECEIVED_DATE_TIME",
comment: "Label for the 'received date & time' field of the 'message metadata' view."),
value: DateUtil.formatPastTimestampRelativeToNow(message.timestampForSorting())))
}
rows += addAttachmentMetadataRows()
// TODO: We could include the "disappearing messages" state here.
var lastRow: UIView?
for row in rows {
contentView.addSubview(row)
row.autoPinLeadingToSuperview()
row.autoPinTrailingToSuperview()
if let lastRow = lastRow {
row.autoPinEdge(.top, to: .bottom, of: lastRow, withOffset: 5)
} else {
row.autoPinEdge(toSuperviewEdge: .top, withInset: 20)
}
lastRow = row
}
if let lastRow = lastRow {
lastRow.autoPinEdge(toSuperviewEdge: .bottom, withInset: 20)
}
if let mediaMessageView = mediaMessageView {
mediaMessageView.autoPinToSquareAspectRatio()
}
}
private func displayableTextIfText() -> String? {
guard viewItem.hasText else {
return nil
}
guard let displayableText = viewItem.displayableText() else {
return nil
}
let messageBody = displayableText.fullText
guard messageBody.count > 0 else {
return nil
}
return messageBody
}
let bubbleViewHMargin: CGFloat = 10
let messageTailEdgeMargin: CGFloat = 15
let messageNoTailEdgeMargin: CGFloat = 10
private func contentRows() -> [UIView] {
var rows = [UIView]()
if message.attachmentIds.count > 0 {
rows += addAttachmentRows()
}
if let messageBody = displayableTextIfText() {
self.messageBody = messageBody
let isIncoming = self.message as? TSIncomingMessage != nil
// UITextView can't render extremely long text due to constraints
// on the size of its backing buffer, especially when we're
// embedding it "full-size' within a UIScrollView as we do in this view.
//
// Therefore we're doing something unusual here.
// See comments on updateTextLayout.
let messageTextView = UITextView()
self.messageTextView = messageTextView
messageTextView.font = UIFont.ows_dynamicTypeBody()
messageTextView.backgroundColor = UIColor.clear
messageTextView.isOpaque = false
messageTextView.isEditable = false
messageTextView.isSelectable = true
messageTextView.textContainerInset = UIEdgeInsets.zero
messageTextView.contentInset = UIEdgeInsets.zero
messageTextView.isScrollEnabled = true
messageTextView.showsHorizontalScrollIndicator = false
messageTextView.showsVerticalScrollIndicator = false
messageTextView.isUserInteractionEnabled = false
messageTextView.textColor = isIncoming ? UIColor.black : UIColor.white
messageTextView.text = messageBody
let bubbleImageData = bubbleFactory.bubble(message: message)
let messageTextProxyView = UIView()
messageTextProxyView.layoutMargins = UIEdgeInsets.zero
self.messageTextProxyView = messageTextProxyView
messageTextProxyView.addSubview(messageTextView)
messageTextView.autoPinWidthToSuperview()
self.messageTextTopConstraint = messageTextView.autoPinEdge(toSuperviewEdge: .top, withInset: 0)
self.messageTextHeightLayoutConstraint = messageTextView.autoSetDimension(.height, toSize:0)
let bubbleView = UIImageView(image: bubbleImageData.messageBubbleImage)
self.bubbleView = bubbleView
bubbleView.layer.cornerRadius = 10
bubbleView.addSubview(messageTextProxyView)
messageTextProxyView.autoPinEdge(toSuperviewEdge: isIncoming ? .leading : .trailing, withInset: messageTailEdgeMargin)
messageTextProxyView.autoPinEdge(toSuperviewEdge: isIncoming ? .trailing : .leading, withInset: messageNoTailEdgeMargin)
messageTextProxyView.autoPinHeightToSuperview(withMargin: 10)
self.messageTextProxyViewHeightConstraint = messageTextProxyView.autoSetDimension(.height, toSize:0)
let row = UIView()
row.addSubview(bubbleView)
bubbleView.autoPinHeightToSuperview()
bubbleView.autoPinEdge(toSuperviewEdge: isIncoming ? .leading : .trailing, withInset: bubbleViewHMargin)
self.bubbleViewWidthConstraint = bubbleView.autoSetDimension(.width, toSize:0)
rows.append(row)
}
if rows.count == 0 {
// Neither attachment nor body.
owsFail("\(self.TAG) Message has neither attachment nor body.")
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_NO_ATTACHMENT_OR_BODY",
comment: "Label for messages without a body or attachment in the 'message metadata' view."),
value: ""))
}
let spacer = UIView()
spacer.autoSetDimension(.height, toSize: 15)
rows.append(spacer)
return rows
}
private func addAttachmentRows() -> [UIView] {
var rows = [UIView]()
guard let attachmentId = message.attachmentIds[0] as? String else {
owsFail("Invalid attachment")
return rows
}
guard let attachment = TSAttachment.fetch(uniqueId: attachmentId) else {
owsFail("Missing attachment")
return rows
}
self.attachment = attachment
guard let attachmentStream = attachment as? TSAttachmentStream else {
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_ATTACHMENT_NOT_YET_DOWNLOADED",
comment: "Label for 'not yet downloaded' attachments in the 'message metadata' view."),
value: ""))
return rows
}
self.attachmentStream = attachmentStream
if let filePath = attachmentStream.filePath() {
dataSource = DataSourcePath.dataSource(withFilePath: filePath)
}
guard let dataSource = dataSource else {
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_ATTACHMENT_MISSING_FILE",
comment: "Label for 'missing' attachments in the 'message metadata' view."),
value: ""))
return rows
}
let contentType = attachment.contentType
if let dataUTI = MIMETypeUtil.utiType(forMIMEType: contentType) {
let attachment = SignalAttachment.attachment(dataSource: dataSource, dataUTI: dataUTI, imageQuality: .original)
let mediaMessageView = MediaMessageView(attachment: attachment, mode: .small)
mediaMessageView.backgroundColor = UIColor.white
self.mediaMessageView = mediaMessageView
rows.append(mediaMessageView)
}
return rows
}
private func addAttachmentMetadataRows() -> [UIView] {
var rows = [UIView]()
if let attachment = self.attachment {
// Only show MIME types in DEBUG builds.
if _isDebugAssertConfiguration() {
let contentType = attachment.contentType
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_ATTACHMENT_MIME_TYPE",
comment: "Label for the MIME type of attachments in the 'message metadata' view."),
value: contentType))
}
if let sourceFilename = attachment.sourceFilename {
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_SOURCE_FILENAME",
comment: "Label for the original filename of any attachment in the 'message metadata' view."),
value: sourceFilename))
}
}
if let dataSource = self.dataSource {
let fileSize = dataSource.dataLength()
rows.append(valueRow(name: NSLocalizedString("MESSAGE_METADATA_VIEW_ATTACHMENT_FILE_SIZE",
comment: "Label for file size of attachments in the 'message metadata' view."),
value: OWSFormat.formatFileSize(UInt(fileSize))))
}
return rows
}
private func nameLabel(text: String) -> UILabel {
let label = UILabel()
label.textColor = UIColor.black
label.font = UIFont.ows_mediumFont(withSize: 14)
label.text = text
label.setContentHuggingHorizontalHigh()
return label
}
private func valueLabel(text: String) -> UILabel {
let label = UILabel()
label.textColor = UIColor.black
label.font = UIFont.ows_regularFont(withSize: 14)
label.text = text
label.setContentHuggingHorizontalLow()
return label
}
private func valueRow(name: String, value: String, subtitle: String = "") -> UIView {
let row = UIView.container()
let nameLabel = self.nameLabel(text: name)
let valueLabel = self.valueLabel(text: value)
row.addSubview(nameLabel)
row.addSubview(valueLabel)
nameLabel.autoPinLeadingToSuperview(withMargin: 20)
valueLabel.autoPinTrailingToSuperview(withMargin: 20)
valueLabel.autoPinLeading(toTrailingOf: nameLabel, margin: 10)
nameLabel.autoPinEdge(toSuperviewEdge: .top)
valueLabel.autoPinEdge(toSuperviewEdge: .top)
if subtitle.count > 0 {
let subtitleLabel = self.valueLabel(text: subtitle)
subtitleLabel.textColor = UIColor.ows_darkGray()
row.addSubview(subtitleLabel)
subtitleLabel.autoPinTrailingToSuperview()
subtitleLabel.autoPinLeading(toTrailingOf: nameLabel, margin: 10)
subtitleLabel.autoPinEdge(.top, to: .bottom, of: valueLabel, withOffset: 1)
subtitleLabel.autoPinEdge(toSuperviewEdge: .bottom)
} else if value.count > 0 {
valueLabel.autoPinEdge(toSuperviewEdge: .bottom)
} else {
nameLabel.autoPinEdge(toSuperviewEdge: .bottom)
}
return row
}
// MARK: - Actions
func shareButtonPressed() {
if let messageBody = messageBody {
UIPasteboard.general.string = messageBody
return
}
guard let attachmentStream = attachmentStream else {
Logger.error("\(TAG) Message has neither attachment nor message body.")
return
}
AttachmentSharing.showShareUI(forAttachment: attachmentStream)
}
func copyToPasteboard() {
if let messageBody = messageBody {
UIPasteboard.general.string = messageBody
return
}
guard let attachmentStream = attachmentStream else {
Logger.error("\(TAG) Message has neither attachment nor message body.")
return
}
guard let utiType = MIMETypeUtil.utiType(forMIMEType: attachmentStream.contentType) else {
Logger.error("\(TAG) Attachment has invalid MIME type: \(attachmentStream.contentType).")
return
}
guard let dataSource = dataSource else {
Logger.error("\(TAG) Attachment missing data source.")
return
}
let data = dataSource.data()
UIPasteboard.general.setData(data, forPasteboardType: utiType)
}
// MARK: - Actions
// This method should be called after self.databaseConnection.beginLongLivedReadTransaction().
private func updateDBConnectionAndMessageToLatest() {
AssertIsOnMainThread()
self.databaseConnection.read { transaction in
guard let uniqueId = self.message.uniqueId else {
Logger.error("\(self.TAG) Message is missing uniqueId.")
return
}
guard let newMessage = TSInteraction.fetch(uniqueId: uniqueId, transaction: transaction) as? TSMessage else {
Logger.error("\(self.TAG) Couldn't reload message.")
return
}
self.message = newMessage
}
}
internal func yapDatabaseModified(notification: NSNotification) {
AssertIsOnMainThread()
let notifications = self.databaseConnection.beginLongLivedReadTransaction()
guard let uniqueId = self.message.uniqueId else {
Logger.error("\(self.TAG) Message is missing uniqueId.")
return
}
guard self.databaseConnection.hasChange(forKey: uniqueId,
inCollection: TSInteraction.collection(),
in: notifications) else {
Logger.debug("\(TAG) No relevant changes.")
return
}
updateDBConnectionAndMessageToLatest()
updateContent()
}
private func string(for messageRecipientStatus: MessageRecipientStatus) -> String {
switch messageRecipientStatus {
case .uploading:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_UPLOADING",
comment: "Status label for messages which are uploading.")
case .sending:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_SENDING",
comment: "Status label for messages which are sending.")
case .sent:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_SENT",
comment: "Status label for messages which are sent.")
case .delivered:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_DELIVERED",
comment: "Status label for messages which are delivered.")
case .read:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_READ",
comment: "Status label for messages which are read.")
case .failed:
return NSLocalizedString("MESSAGE_METADATA_VIEW_MESSAGE_STATUS_FAILED",
comment: "Status label for messages which are failed.")
}
}
// MARK: - Text Layout
// UITextView can't render extremely long text due to constraints on the size
// of its backing buffer, especially when we're embedding it "full-size'
// within a UIScrollView as we do in this view. Therefore if we do the naive
// thing and embed a full-size UITextView inside our UIScrollView, it will
// fail to render any text if the text message is sufficiently long.
//
// Therefore we're doing something unusual.
//
// * We use an empty UIView "messageTextProxyView" as a placeholder for the
// the UITextView. It has the size and position of where the UITextView
// would be normally.
// * We use a UITextView inside that proxy that is just large enough to
// render the content onscreen. We then move it around within the proxy
// bounds to render the parts of the proxy which are onscreen.
private func updateTextLayout() {
guard let messageTextView = messageTextView else {
return
}
guard let messageTextProxyView = messageTextProxyView else {
owsFail("\(TAG) Missing messageTextProxyView")
return
}
guard let scrollView = scrollView else {
owsFail("\(TAG) Missing scrollView")
return
}
guard let contentView = contentView else {
owsFail("\(TAG) Missing contentView")
return
}
guard let bubbleView = bubbleView else {
owsFail("\(TAG) Missing bubbleView")
return
}
guard let bubbleSuperview = bubbleView.superview else {
owsFail("\(TAG) Missing bubbleSuperview")
return
}
guard let messageTextTopConstraint = messageTextTopConstraint else {
owsFail("\(TAG) Missing messageTextTopConstraint")
return
}
guard let messageTextHeightLayoutConstraint = messageTextHeightLayoutConstraint else {
owsFail("\(TAG) Missing messageTextHeightLayoutConstraint")
return
}
guard let messageTextProxyViewHeightConstraint = messageTextProxyViewHeightConstraint else {
owsFail("\(TAG) Missing messageTextProxyViewHeightConstraint")
return
}
guard let bubbleViewWidthConstraint = bubbleViewWidthConstraint else {
owsFail("\(TAG) Missing bubbleViewWidthConstraint")
return
}
if messageTextView.width() != messageTextProxyView.width() {
owsFail("\(TAG) messageTextView.width \(messageTextView.width) != messageTextProxyView.width \(messageTextProxyView.width)")
}
let maxBubbleWidth = bubbleSuperview.width() - (bubbleViewHMargin * 2)
let maxTextWidth = maxBubbleWidth - (messageTailEdgeMargin + messageNoTailEdgeMargin)
// Measure the total text size.
let textSize = messageTextView.sizeThatFits(CGSize(width:maxTextWidth, height:CGFloat.greatestFiniteMagnitude))
// Measure the size of the scroll view viewport.
let scrollViewSize = scrollView.frame.size
// Obtain the current scroll view content offset (scroll state).
let scrollViewContentOffset = scrollView.contentOffset
// Obtain the location of the text view proxy relative to the content view.
let textProxyOffset = contentView.convert(CGPoint.zero, from:messageTextProxyView)
// 1. The bubble view's width should fit the text content.
let bubbleViewWidth = ceil(textSize.width + messageTailEdgeMargin + messageNoTailEdgeMargin)
bubbleViewWidthConstraint.constant = bubbleViewWidth
// 2. The text proxy's height should reflect the entire text content.
let messageTextProxyViewHeight = ceil(textSize.height)
messageTextProxyViewHeightConstraint.constant = messageTextProxyViewHeight
// 3. We only want to render a single screenful of text content at a time.
// The height of the text view should reflect the height of the scrollview's
// viewport.
let messageTextViewHeight = ceil(min(textSize.height, scrollViewSize.height))
messageTextHeightLayoutConstraint.constant = messageTextViewHeight
// 4. We want to move the text view around within the proxy in response to
// scroll state changes so that it can render the part of the proxy which
// is on screen.
let minMessageTextViewY = CGFloat(0)
let maxMessageTextViewY = messageTextProxyViewHeight - messageTextViewHeight
let rawMessageTextViewY = -textProxyOffset.y + scrollViewContentOffset.y
let messageTextViewY = max(minMessageTextViewY, min(maxMessageTextViewY, rawMessageTextViewY))
messageTextTopConstraint.constant = messageTextViewY
// 5. We want to scroll the text view's content so that the text view
// renders the appropriate content for the scrollview's scroll state.
messageTextView.contentOffset = CGPoint(x:0, y:messageTextViewY)
}
public func scrollViewDidScroll(_ scrollView: UIScrollView) {
Logger.verbose("\(TAG) scrollViewDidScroll")
updateTextLayout()
}
}