Files
MessageKit/Sources/MessagesCollectionViewFlowLayout.swift
T

602 lines
27 KiB
Swift

/*
MIT License
Copyright (c) 2017 MessageKit
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
import UIKit
import AVFoundation
open class MessagesCollectionViewFlowLayout: UICollectionViewFlowLayout {
// MARK: - Properties
open var messageLabelFont: UIFont
open var messageToViewEdgePadding: CGFloat
open var avatarAlwaysLeading: Bool {
willSet {
if newValue {
avatarAlwaysTrailing = false
}
}
}
open var avatarAlwaysTrailing: Bool {
willSet {
if newValue {
avatarAlwaysLeading = false
}
}
}
fileprivate var avatarMessagePadding: CGFloat = 4
fileprivate var messagesCollectionView: MessagesCollectionView? {
return collectionView as? MessagesCollectionView
}
fileprivate var itemWidth: CGFloat {
guard let collectionView = collectionView else { return 0 }
return collectionView.frame.width - sectionInset.left - sectionInset.right
}
override open class var layoutAttributesClass: AnyClass {
return MessagesCollectionViewLayoutAttributes.self
}
// MARK: - Initializers
override public init() {
messageLabelFont = UIFont.preferredFont(forTextStyle: .body)
messageToViewEdgePadding = 30.0
avatarAlwaysLeading = false
avatarAlwaysTrailing = false
super.init()
sectionInset = UIEdgeInsets(top: 4, left: 8, bottom: 4, right: 8)
}
required public init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
// MARK: - Methods
// MARK: - Layout Attributes
override open func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
guard let attributesArray = super.layoutAttributesForElements(in: rect) as? [MessagesCollectionViewLayoutAttributes] else { return nil }
attributesArray.forEach { attributes in
if attributes.representedElementCategory == UICollectionElementCategory.cell {
configure(attributes: attributes)
}
}
return attributesArray
}
override open func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
guard let attributes = super.layoutAttributesForItem(at: indexPath) as? MessagesCollectionViewLayoutAttributes else { return nil }
if attributes.representedElementCategory == UICollectionElementCategory.cell {
configure(attributes: attributes)
}
return attributes
}
private func configure(attributes: MessagesCollectionViewLayoutAttributes) {
guard let messagesCollectionView = messagesCollectionView else { return }
guard let dataSource = messagesCollectionView.messagesDataSource else { return }
let indexPath = attributes.indexPath
let message = dataSource.messageForItem(at: indexPath, in: messagesCollectionView)
let messageInsets = messageLabelInsets(for: message, at: indexPath)
let topLabelInsets = cellTopLabelInsets(for: message, at: indexPath)
let bottomLabelInsets = cellBottomLabelInsets(for: message, at: indexPath)
// First we set all the sizes so we can pass the attributes object around to calculate the origins
attributes.messageContainerFrame = CGRect(origin: .zero, size: messageContainerSize(for: message, at: indexPath))
attributes.cellTopLabelFrame = CGRect(origin: .zero, size: cellTopLabelSize(for: message, at: indexPath))
attributes.cellBottomLabelFrame = CGRect(origin: .zero, size: cellBottomLabelSize(for: message, at: indexPath))
attributes.avatarFrame = CGRect(origin: .zero, size: avatarSize(for: message, at: indexPath))
attributes.messageLabelFont = messageLabelFont
attributes.messageLabelInsets = messageInsets
attributes.cellTopLabelInsets = topLabelInsets
attributes.cellBottomLabelInsets = bottomLabelInsets
attributes.avatarHorizontalAlignment = avatarHorizontalAlignment(for: message)
let layoutDelegate = messagesCollectionView.messagesLayoutDelegate
let avatarAlignment = layoutDelegate?.avatarAlignment(for: message, at: indexPath, in: messagesCollectionView) ?? .messageBottom
// Now we set the origins for the frames using the attributes object that contains the calculated sizes
attributes.messageContainerFrame.origin = messageContainerOrigin(for: attributes)
attributes.cellTopLabelFrame.origin = cellTopLabelOrigin(for: message, and: attributes)
attributes.cellBottomLabelFrame.origin = cellBottomLabelOrigin(for: message, and: attributes)
attributes.avatarFrame.origin = avatarOrigin(for: attributes, with: avatarAlignment)
}
// MARK: - Invalidation Context
override open func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
return collectionView?.bounds.width != newBounds.width || collectionView?.bounds.height != newBounds.height
}
open override func invalidationContext(forBoundsChange newBounds: CGRect) -> UICollectionViewLayoutInvalidationContext {
let context = super.invalidationContext(forBoundsChange: newBounds)
guard let flowLayoutContext = context as? UICollectionViewFlowLayoutInvalidationContext else { return context }
flowLayoutContext.invalidateFlowLayoutDelegateMetrics = shouldInvalidateLayout(forBoundsChange: newBounds)
return flowLayoutContext
}
}
extension MessagesCollectionViewFlowLayout {
// MARK: - Avatar Calculations
/// The horizontal alignment for the message: .cellTrailing or .cellLeading
fileprivate func avatarHorizontalAlignment(for message: MessageType) -> AvatarHorizontalAlignment {
if avatarAlwaysTrailing { return .cellTrailing }
if avatarAlwaysLeading { return .cellLeading }
guard let messagesCollectionView = messagesCollectionView else { return .cellLeading }
guard let messagesDataSource = messagesCollectionView.messagesDataSource else { return .cellLeading }
return messagesDataSource.isFromCurrentSender(message: message) ? .cellTrailing : .cellLeading
}
/// The size of the avatar view.
fileprivate func avatarSize(for message: MessageType, at indexPath: IndexPath) -> CGSize {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
return layoutDelegate.avatarSize(for: message, at: indexPath, in: messagesCollectionView)
}
/// The origin for the avatar view.
fileprivate func avatarOrigin(for attributes: MessagesCollectionViewLayoutAttributes, with avatarAlignment: AvatarAlignment) -> CGPoint {
var origin = CGPoint.zero
let contentWidth = attributes.frame.size.width
let avatarWidth = attributes.avatarFrame.size.width
switch attributes.avatarHorizontalAlignment {
case .cellLeading:
origin.x = 0
case .cellTrailing:
origin.x = contentWidth - avatarWidth
}
let contentHeight = attributes.frame.height
let avatarHeight = attributes.avatarFrame.height
let cellTopLabelHeight = attributes.cellTopLabelFrame.height
let cellBottomLabelHeight = attributes.cellBottomLabelFrame.height
let messageContainerHeight = attributes.messageContainerFrame.height
switch avatarAlignment {
case .cellTop:
origin.y = 0
case .cellBottom:
origin.y = contentHeight - avatarHeight
case .messageTop:
origin.y = cellTopLabelHeight
case .messageBottom:
origin.y = contentHeight - avatarHeight - cellBottomLabelHeight
case .messageCenter:
let messageMidY = messageContainerHeight / 2
let avatarMidY = avatarHeight / 2
origin.y = contentHeight - cellTopLabelHeight - messageMidY - avatarMidY
}
return origin
}
// MARK: - Label Size Calculations
/// The size required fit a NSAttributedString considering a constrained max width.
fileprivate func labelSize(for attributedText: NSAttributedString, considering maxWidth: CGFloat) -> CGSize {
let estimatedHeight = attributedText.height(considering: maxWidth)
let estimatedWidth = attributedText.width(considering: estimatedHeight)
let finalHeight = estimatedHeight.rounded(.up)
let finalWidth = estimatedWidth > maxWidth ? maxWidth : estimatedWidth.rounded(.up)
return CGSize(width: finalWidth, height: finalHeight)
}
/// The size required to fit a String considering a constrained max width.
fileprivate func labelSize(for text: String, considering maxWidth: CGFloat, and font: UIFont) -> CGSize {
let estimatedHeight = text.height(considering: maxWidth, and: font)
let estimatedWidth = text.width(considering: estimatedHeight, and: font)
let finalHeight = estimatedHeight.rounded(.up)
let finalWidth = estimatedWidth > maxWidth ? maxWidth : estimatedWidth.rounded(.up)
return CGSize(width: finalWidth, height: finalHeight)
}
// MARK: - Message Container Calculations
/// The insets for the text of the MessageLabel
private func messageLabelInsets(for message: MessageType, at indexPath: IndexPath) -> UIEdgeInsets {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
return layoutDelegate.messageLabelInset(for: message, at: indexPath, in: messagesCollectionView)
}
/// The max width available for the message container.
private func messageContainerMaxWidth(for message: MessageType, at indexPath: IndexPath) -> CGFloat {
var avatarWidth = avatarSize(for: message, at: indexPath).width
// Only apply padding if avatar width is greater than zero
if avatarWidth > 0 { avatarWidth += avatarMessagePadding }
let messageInsets = messageLabelInsets(for: message, at: indexPath)
let messageHorizontalInsets = messageInsets.left + messageInsets.right
let availableWidth = itemWidth - avatarWidth - messageToViewEdgePadding - messageHorizontalInsets
return availableWidth
}
/// The size for the message container.
fileprivate func messageContainerSize(for message: MessageType, at indexPath: IndexPath) -> CGSize {
let maxWidth = messageContainerMaxWidth(for: message, at: indexPath)
let messageInsets = messageLabelInsets(for: message, at: indexPath)
let messageHorizontalInsets = messageInsets.left + messageInsets.right
let messageVerticalInsets = messageInsets.top + messageInsets.bottom
var messageContainerSize: CGSize = .zero
switch message.data {
case .text(let text):
messageContainerSize = labelSize(for: text, considering: maxWidth, and: messageLabelFont)
messageContainerSize.width += messageHorizontalInsets
messageContainerSize.height += messageVerticalInsets
case .attributedText(let text):
messageContainerSize = labelSize(for: text, considering: maxWidth)
messageContainerSize.width += messageHorizontalInsets
messageContainerSize.height += messageVerticalInsets
case .photo, .video:
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate as? MediaMessageLayoutDelegate else { return .zero }
let width = layoutDelegate.widthForMedia(message: message, at: indexPath, with: maxWidth, in: messagesCollectionView)
let height = layoutDelegate.heightForMedia(message: message, at: indexPath, with: maxWidth, in: messagesCollectionView)
messageContainerSize = CGSize(width: width, height: height)
case .location:
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate as? LocationMessageLayoutDelegate else { return .zero }
let width = layoutDelegate.widthForLocation(message: message, at: indexPath, with: maxWidth, in: messagesCollectionView)
let height = layoutDelegate.heightForLocation(message: message, at: indexPath, with: maxWidth, in: messagesCollectionView)
messageContainerSize = CGSize(width: width, height: height)
}
return messageContainerSize
}
/// The origin for the message container.
fileprivate func messageContainerOrigin(for attributes: MessagesCollectionViewLayoutAttributes) -> CGPoint {
var avatarWidth = attributes.avatarFrame.width
if avatarWidth > 0 { avatarWidth += avatarMessagePadding }
var origin = CGPoint.zero
switch attributes.avatarHorizontalAlignment {
case .cellLeading:
origin.x = avatarWidth
origin.y = attributes.cellTopLabelFrame.height
case .cellTrailing:
origin.x = attributes.frame.width - avatarWidth - attributes.messageContainerFrame.width
origin.y = attributes.cellTopLabelFrame.height
}
return origin
}
// MARK: - Cell Top Label Calculations
/// The insets for the cell's top label.
private func cellTopLabelInsets(for message: MessageType, at indexPath: IndexPath) -> UIEdgeInsets {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
let labelAlignment = layoutDelegate.cellTopLabelAlignment(for: message, at: indexPath, in: messagesCollectionView)
return labelAlignment.insets
}
/// The max width available for the cell top label.
private func topLabelMaxWidth(for message: MessageType, at indexPath: IndexPath) -> CGFloat {
guard let messagesCollectionView = messagesCollectionView else { return 0 }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return 0 }
let labelHorizontal = layoutDelegate.cellTopLabelAlignment(for: message, at: indexPath, in: messagesCollectionView)
let avatarVertical = layoutDelegate.avatarAlignment(for: message, at: indexPath, in: messagesCollectionView)
let avatarHorizontal = avatarHorizontalAlignment(for: message)
let topLabelHorizontalInsets = labelHorizontal.insets.left + labelHorizontal.insets.right
var avatarWidth = layoutDelegate.avatarSize(for: message, at: indexPath, in: messagesCollectionView).width
// Only apply padding is avatar width is greater than zero
if avatarWidth > 0 { avatarWidth += avatarMessagePadding }
switch (labelHorizontal, avatarHorizontal, avatarVertical) {
case (.cellLeading, .cellTrailing, .cellTop), (.cellTrailing, .cellLeading, .cellTop):
return itemWidth - avatarWidth - topLabelHorizontalInsets
case (.cellLeading, _, _), (.cellTrailing, _, _):
return itemWidth - topLabelHorizontalInsets
case (.cellCenter, .cellLeading, .cellTop), (.cellCenter, .cellTrailing, .cellTop):
return itemWidth - (avatarWidth * 2) - topLabelHorizontalInsets
case (.cellCenter, .cellLeading, _), (.cellCenter, .cellTrailing, _):
return itemWidth - topLabelHorizontalInsets
case (.messageTrailing, .cellLeading, .cellTop), (.messageLeading, .cellTrailing, .cellTop):
return messageContainerSize(for: message, at: indexPath).width - topLabelHorizontalInsets
case (.messageLeading, .cellLeading, _), (.messageTrailing, .cellTrailing, _):
return itemWidth - avatarWidth - topLabelHorizontalInsets
case (.messageLeading, .cellTrailing, _), (.messageTrailing, .cellLeading, _):
return messageContainerSize(for: message, at: indexPath).width + avatarWidth - topLabelHorizontalInsets
}
}
/// The size of the cell top label.
fileprivate func cellTopLabelSize(for message: MessageType, at indexPath: IndexPath) -> CGSize {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let dataSource = messagesCollectionView.messagesDataSource else { return .zero }
guard let topLabelText = dataSource.cellTopLabelAttributedText(for: message, at: indexPath) else { return .zero }
let maxWidth = topLabelMaxWidth(for: message, at: indexPath)
var size = labelSize(for: topLabelText, considering: maxWidth)
let topLabelInsets = cellTopLabelInsets(for: message, at: indexPath)
let topLabelHorizontalInsets = topLabelInsets.left + topLabelInsets.right
let topLabelVerticalInsets = topLabelInsets.top + topLabelInsets.bottom
size.width += topLabelHorizontalInsets
size.height += topLabelVerticalInsets
return size
}
/// The origin for the cell top label.
fileprivate func cellTopLabelOrigin(for message: MessageType, and attributes: MessagesCollectionViewLayoutAttributes) -> CGPoint {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
let labelAlignment = layoutDelegate.cellTopLabelAlignment(for: message, at: attributes.indexPath, in: messagesCollectionView)
let avatarAlignment = avatarHorizontalAlignment(for: message)
var origin = CGPoint.zero
switch (labelAlignment, avatarAlignment) {
case (.cellLeading, _):
origin.x = 0
case (.cellCenter, _):
origin.x = attributes.frame.width / 2 - (attributes.cellTopLabelFrame.width / 2)
case (.cellTrailing, _):
origin.x = attributes.frame.width - attributes.cellTopLabelFrame.width
case (.messageLeading, .cellLeading):
origin.x = attributes.avatarFrame.width + avatarMessagePadding
case (.messageLeading, .cellTrailing):
origin.x = attributes.frame.width - attributes.avatarFrame.width - avatarMessagePadding - attributes.messageContainerFrame.width
case (.messageTrailing, .cellTrailing):
origin.x = attributes.frame.width - attributes.avatarFrame.width - avatarMessagePadding - attributes.cellTopLabelFrame.width
case (.messageTrailing, .cellLeading):
origin.x = attributes.frame.width - messageToViewEdgePadding - attributes.cellTopLabelFrame.width
}
return origin
}
// MARK: - Cell Bottom Label Calculations
/// The insets for the cell's top label.
private func cellBottomLabelInsets(for message: MessageType, at indexPath: IndexPath) -> UIEdgeInsets {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
let labelAlignment = layoutDelegate.cellBottomLabelAlignment(for: message, at: indexPath, in: messagesCollectionView)
return labelAlignment.insets
}
/// The max with available for the cell bottom label.
private func bottomLabelMaxWidth(for message: MessageType, at indexPath: IndexPath) -> CGFloat {
guard let messagesCollectionView = messagesCollectionView else { return 0 }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return 0 }
let labelHorizontal = layoutDelegate.cellBottomLabelAlignment(for: message, at: indexPath, in: messagesCollectionView)
let avatarVertical = layoutDelegate.avatarAlignment(for: message, at: indexPath, in: messagesCollectionView)
let avatarHorizontal = avatarHorizontalAlignment(for: message)
let bottomLabelHorizontalInsets = labelHorizontal.insets.left + labelHorizontal.insets.right
var avatarWidth = layoutDelegate.avatarSize(for: message, at: indexPath, in: messagesCollectionView).width
// Only apply padding is avatar width is greater than zero
if avatarWidth > 0 { avatarWidth += avatarMessagePadding }
switch (labelHorizontal, avatarHorizontal, avatarVertical) {
case (.cellLeading, .cellTrailing, .cellBottom), (.cellTrailing, .cellLeading, .cellBottom):
return itemWidth - avatarWidth - bottomLabelHorizontalInsets
case (.cellLeading, _, _), (.cellTrailing, _, _):
return itemWidth - bottomLabelHorizontalInsets
case (.cellCenter, .cellLeading, .cellBottom), (.cellCenter, .cellTrailing, .cellBottom):
return itemWidth - (avatarWidth * 2) - bottomLabelHorizontalInsets
case (.cellCenter, .cellLeading, _), (.cellCenter, .cellTrailing, _):
return itemWidth - bottomLabelHorizontalInsets
case (.messageTrailing, .cellLeading, .cellBottom), (.messageLeading, .cellTrailing, .cellBottom):
return messageContainerSize(for: message, at: indexPath).width - bottomLabelHorizontalInsets
case (.messageLeading, .cellLeading, _), (.messageTrailing, .cellTrailing, _):
return itemWidth - avatarWidth - bottomLabelHorizontalInsets
case (.messageLeading, .cellTrailing, _), (.messageTrailing, .cellLeading, _):
return messageContainerSize(for: message, at: indexPath).width + avatarWidth - bottomLabelHorizontalInsets
}
}
/// The size for the cell bottom label.
fileprivate func cellBottomLabelSize(for message: MessageType, at indexPath: IndexPath) -> CGSize {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let dataSource = messagesCollectionView.messagesDataSource else { return .zero }
guard let bottomLabelText = dataSource.cellBottomLabelAttributedText(for: message, at: indexPath) else { return .zero }
let maxWidth = bottomLabelMaxWidth(for: message, at: indexPath)
var size = labelSize(for: bottomLabelText, considering: maxWidth)
let bottomLabelInsets = cellBottomLabelInsets(for: message, at: indexPath)
let bottomLabelHorizontalInsets = bottomLabelInsets.left + bottomLabelInsets.right
let bottomLabelVerticalInsets = bottomLabelInsets.top + bottomLabelInsets.bottom
size.width += bottomLabelHorizontalInsets
size.height += bottomLabelVerticalInsets
return size
}
/// The origin for the cell bottom label.
fileprivate func cellBottomLabelOrigin(for message: MessageType, and attributes: MessagesCollectionViewLayoutAttributes) -> CGPoint {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return .zero }
let labelAlignment = layoutDelegate.cellBottomLabelAlignment(for: message, at: attributes.indexPath, in: messagesCollectionView)
let avatarAlignment = avatarHorizontalAlignment(for: message)
var origin = CGPoint(x: 0, y: attributes.frame.height - attributes.cellBottomLabelFrame.height)
switch (labelAlignment, avatarAlignment) {
case (.cellLeading, _):
origin.x = 0
case (.cellCenter, _):
origin.x = attributes.frame.width / 2 - (attributes.cellBottomLabelFrame.width / 2)
case (.cellTrailing, _):
origin.x = attributes.frame.width - attributes.cellBottomLabelFrame.width
case (.messageLeading, .cellLeading):
origin.x = attributes.avatarFrame.width + avatarMessagePadding
case (.messageLeading, .cellTrailing):
origin.x = attributes.frame.width - attributes.avatarFrame.width - avatarMessagePadding - attributes.messageContainerFrame.width
case (.messageTrailing, .cellTrailing):
origin.x = attributes.frame.width - attributes.avatarFrame.width - avatarMessagePadding - attributes.cellBottomLabelFrame.width
case (.messageTrailing, .cellLeading):
origin.x = attributes.avatarFrame.width + avatarMessagePadding + attributes.messageContainerFrame.width - attributes.cellBottomLabelFrame.width
}
return origin
}
// MARK: - Cell Size Calculations
/// The minimum height for the cell.
private func minimumCellHeight(for message: MessageType, at indexPath: IndexPath) -> CGFloat {
guard let messagesCollectionView = messagesCollectionView else { return 0 }
guard let layoutDelegate = messagesCollectionView.messagesLayoutDelegate else { return 0 }
let avatarAlignment = layoutDelegate.avatarAlignment(for: message, at: indexPath, in: messagesCollectionView)
let topLabelHeight = cellTopLabelSize(for: message, at: indexPath).height
let avatarHeight = avatarSize(for: message, at: indexPath).height
let bottomLabelHeight = cellBottomLabelSize(for: message, at: indexPath).height
switch avatarAlignment {
case .cellTop:
return max(avatarHeight, topLabelHeight) + bottomLabelHeight
case .cellBottom:
return max(avatarHeight, bottomLabelHeight) + topLabelHeight
case .messageTop, .messageCenter, .messageBottom:
return topLabelHeight + avatarHeight + bottomLabelHeight
}
}
/// The calculated height of the cell not considering the minimum height.
private func estimatedCellHeight(for message: MessageType, at indexPath: IndexPath) -> CGFloat {
let messageContainerHeight = messageContainerSize(for: message, at: indexPath).height
let cellTopLabelHeight = cellTopLabelSize(for: message, at: indexPath).height
let cellBottomLabelHeight = cellBottomLabelSize(for: message, at: indexPath).height
return messageContainerHeight + cellBottomLabelHeight + cellTopLabelHeight
}
/// The size for the cell considering all cell contents.
open func sizeForItem(at indexPath: IndexPath) -> CGSize {
guard let messagesCollectionView = messagesCollectionView else { return .zero }
guard let dataSource = messagesCollectionView.messagesDataSource else { return .zero }
let message = dataSource.messageForItem(at: indexPath, in: messagesCollectionView)
let minimumHeight = minimumCellHeight(for: message, at: indexPath)
let estimatedHeight = estimatedCellHeight(for: message, at: indexPath)
let itemHeight = estimatedHeight > minimumHeight ? estimatedHeight : minimumHeight
return CGSize(width: itemWidth, height: itemHeight)
}
}