问题
I have a UITableView that I am using for showing chat messages. The cells of this table view are either left or right-aligned and have dynamic width. The menu displayed by shouldShowMenuForRowAt is shown at the horizontal center of the table view cell. Is there a way to shift it to the left or the right edge?
func tableView(_ tableView: UITableView, shouldShowMenuForRowAt indexPath: IndexPath) -> Bool {
return true
}
func tableView(_ tableView: UITableView, canPerformAction action: Selector, forRowAt indexPath: IndexPath, withSender sender: Any?) -> Bool {
return action == #selector(copy(_:))
}
func tableView(_ tableView: UITableView, performAction action: Selector, forRowAt indexPath: IndexPath, withSender sender: Any?) {
if action == #selector(copy(_:)) {
if let cell = tableView.cellForRow(at: indexPath) as? DiscussionChatMessageCell {
let pasteboard = UIPasteboard.general
pasteboard.string = cell.getMessageLabel().text
}
}
}
Output:
Can the actions for cells be left and right aligned?
Message Cell:
class DiscussionChatMessageCell: UITableViewCell {
private let messageLabel: UITextView
private let senderNameLabel: UILabel
private let messageSentTimeLabel: UILabel
private let messageBubble: UIView
private var bubbleLeadingConstraint: NSLayoutConstraint!
private var bubbleTrailingConstraint: NSLayoutConstraint!
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
messageLabel = UITextView()
senderNameLabel = UILabel()
messageSentTimeLabel = UILabel()
messageBubble = UIView()
super.init(style: style, reuseIdentifier: reuseIdentifier)
selectionStyle = .none
self.contentView.addSubview(messageBubble)
messageBubble.translatesAutoresizingMaskIntoConstraints = false
messageBubble.addSubview(senderNameLabel)
senderNameLabel.translatesAutoresizingMaskIntoConstraints = false
senderNameLabel.numberOfLines = 0
senderNameLabel.lineBreakMode = .byCharWrapping
senderNameLabel.font = getFont(name: .HelveticaNeueBold, size: .large)
senderNameLabel.textColor = .white
messageBubble.addSubview(messageLabel)
messageLabel.translatesAutoresizingMaskIntoConstraints = false
messageLabel.isEditable = false
messageLabel.isSelectable = false
messageLabel.dataDetectorTypes = .all
messageLabel.textContainer.lineBreakMode = .byWordWrapping
messageLabel.isScrollEnabled = false
messageLabel.backgroundColor = .clear
messageLabel.isUserInteractionEnabled = true
// messageLabel.numberOfLines = 0
// messageLabel.lineBreakMode = .byWordWrapping
messageLabel.font = getFont(name: .HelveticaNeue, size: .medium)
messageBubble.addSubview(messageSentTimeLabel)
messageSentTimeLabel.translatesAutoresizingMaskIntoConstraints = false
messageSentTimeLabel.lineBreakMode = .byCharWrapping
messageSentTimeLabel.numberOfLines = 0
messageSentTimeLabel.font = getFont(name: .HelveticaNeueItalic, size: .small)
// set hugging and compression resistance for Name label
senderNameLabel.setContentCompressionResistancePriority(.required, for: .vertical)
senderNameLabel.setContentHuggingPriority(.required, for: .vertical)
// create bubble Leading and Trailing constraints
bubbleLeadingConstraint = messageBubble.leadingAnchor.constraint(equalTo: self.contentView.leadingAnchor, constant: 10)
bubbleTrailingConstraint = messageBubble.trailingAnchor.constraint(equalTo: self.contentView.trailingAnchor, constant: -10)
// priority will be changed in configureCell()
bubbleLeadingConstraint.priority = .defaultHigh
bubbleTrailingConstraint.priority = .defaultLow
NSLayoutConstraint.activate([
bubbleLeadingConstraint,
bubbleTrailingConstraint,
messageBubble.topAnchor.constraint(equalTo: self.contentView.topAnchor, constant: 10),
messageBubble.bottomAnchor.constraint(equalTo: self.contentView.bottomAnchor, constant: -10),
messageBubble.widthAnchor.constraint(lessThanOrEqualTo: self.contentView.widthAnchor, constant: -100),
senderNameLabel.topAnchor.constraint(equalTo: messageBubble.topAnchor, constant: 10),
senderNameLabel.leadingAnchor.constraint(equalTo: messageBubble.leadingAnchor, constant: 10),
senderNameLabel.trailingAnchor.constraint(equalTo: messageBubble.trailingAnchor, constant: -10),
messageLabel.topAnchor.constraint(equalTo: senderNameLabel.bottomAnchor, constant: 10),
messageLabel.leadingAnchor.constraint(equalTo: messageBubble.leadingAnchor, constant: 10),
messageLabel.trailingAnchor.constraint(equalTo: messageBubble.trailingAnchor, constant: -10),
messageLabel.bottomAnchor.constraint(equalTo: messageSentTimeLabel.topAnchor, constant: -10),
messageSentTimeLabel.leadingAnchor.constraint(equalTo: messageBubble.leadingAnchor, constant: 10),
messageSentTimeLabel.trailingAnchor.constraint(equalTo: messageBubble.trailingAnchor, constant: -10),
messageSentTimeLabel.bottomAnchor.constraint(equalTo: messageBubble.bottomAnchor, constant: -10),
])
// corners will have radius: 10
messageBubble.layer.cornerRadius = 10
}
func getMessageLabel() -> UITextView {
return messageLabel
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func configureCell(message: DiscussionMessage, isSender: Bool, previousMessage: DiscussionMessage?) {
let senderName = isSender ? "You" : message.userName
senderNameLabel.text = senderName + " " + message.userCountryEmoji
let date = Date(timeIntervalSince1970: message.messageTimestamp)
let dayTimePeriodFormatter = DateFormatter()
dayTimePeriodFormatter.timeZone = .current
dayTimePeriodFormatter.dateFormat = "hh:mm a"
let dateString = dayTimePeriodFormatter.string(from: date)
messageLabel.text = message.message
messageSentTimeLabel.text = dateString
messageLabel.textColor = isSender ? .black : .white
senderNameLabel.textColor = isSender ? .black : .white
messageSentTimeLabel.textColor = isSender ? .black : .white
messageSentTimeLabel.textAlignment = isSender ? .right : .left
bubbleLeadingConstraint.priority = isSender ? .defaultLow : .defaultHigh
bubbleTrailingConstraint.priority = isSender ? .defaultHigh : .defaultLow
messageBubble.backgroundColor = isSender ? accentColor : .gray
let senderCorners: CACornerMask = [.layerMinXMinYCorner, .layerMaxXMinYCorner, .layerMinXMaxYCorner]
let nonSenderCorners: CACornerMask = [.layerMinXMinYCorner, .layerMaxXMinYCorner, .layerMaxXMaxYCorner]
messageBubble.layer.maskedCorners = isSender ?
// topLeft, topRight, bottomRight
senderCorners
:
// topLeft, topRight, bottomLeft
nonSenderCorners
//
// if let previousMessage = previousMessage {
// if message.userEmailAddress == previousMessage.userEmailAddress && message.userCountryCode == previousMessage.userCountryCode && isSender {
// senderNameLabel.isHidden = true
// } else {
// senderNameLabel.isHidden = false
// }
// } else {
// senderNameLabel.isHidden = false
// }
}
}
来源：https://stackoverflow.com/questions/65840591/left-or-right-align-shouldshowmenuforrowat-menu-for-a-custom-uitableview-cell