在Swift中以编程方式将UIImageView左右对齐

Question

我正在使用带有消息气泡的聊天应用程序。 我已经弄清楚了如何根据发送消息的人有条件地格式化消息（颜色，大小等）。 但是，我很难让聊天气泡对准视图控制器的左侧或右侧。 现在，所有项目都向左对齐。 我已经搜索了SO，却找不到答案，所以我决定问。

更新：显示setCell函数的其余代码，该代码根据'incoming'的值确定消息的格式。 还包括tableView函数以显示单元配置。 最后一个功能是设置功能。

func setCell(cell: ConversationCell, incoming: [Int], indexPath: IndexPath) {

    var layoutAttribute: NSLayoutAttribute
    var layoutConstant: CGFloat
    var smavalayoutConstant: CGFloat
    for i in 0 ..< self.incoming.count {

        if (self.incoming[indexPath.row] == 1) {
            cell.bubbleImageView.image=#imageLiteral(resourceName: "chat_bubble_received")
            cell.messageLbl.textColor = UIColor.black
            cell.messageLbl.textAlignment = .left
            cell.messageLbl?.numberOfLines = 0
            cell.messageLbl?.lineBreakMode = .byWordWrapping
            layoutAttribute = .left
            layoutConstant = 0
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.bubbleImageView, attribute: .left, relatedBy: .equal, toItem: cell.contentView, attribute: layoutAttribute, multiplier: 1, constant: layoutConstant))
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.smavaImg, attribute: .left, relatedBy: .equal, toItem: cell.contentView, attribute: layoutAttribute, multiplier: 1, constant: layoutConstant))
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.postpictureImg, attribute: .left, relatedBy: .equal, toItem: cell.contentView, attribute: layoutAttribute, multiplier: 1, constant: layoutConstant))
        }
        if (self.incoming[indexPath.row] == 0) {
            cell.bubbleImageView.image = #imageLiteral(resourceName: "chat_bubble_sent")
            cell.messageLbl.textColor = UIColor.white
            cell.messageLbl.textAlignment = .right
            layoutAttribute = .right
            layoutConstant = -100
            smavalayoutConstant = 300
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.bubbleImageView, attribute: .leftMargin, relatedBy: .lessThanOrEqual, toItem: cell.contentView, attribute: layoutAttribute, multiplier: 1, constant: layoutConstant))
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.bubbleImageView, attribute: .right, relatedBy: .equal, toItem: cell.contentView, attribute: layoutAttribute, multiplier: 1, constant: layoutConstant))
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.smavaImg, attribute: .right, relatedBy: .equal, toItem: cell.smavaImg, attribute: layoutAttribute, multiplier: 1, constant: smavalayoutConstant))
            cell.contentView.addConstraint(NSLayoutConstraint(item: cell.smavaImg, attribute: .left, relatedBy: .equal, toItem: cell.smavaImg, attribute: .left, multiplier: 1, constant: 300))


        }
    }
}

//单元格配置

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! ConversationCell

// shortcuts
let hhpost = hhmessages[indexPath.row]
let image = avas[indexPath.row]
let smimages = images[indexPath.row]


let messagetext = hhpost["messagetext"] as? String
let date = hhpost["date"] as? String
cell.messageLbl.text = messagetext
cell.dateLbl.text = date
cell.smavaImg.image = image
cell.postpictureImg.image = smimages
DispatchQueue.main.async {

    tableView.transform = CGAffineTransform(rotationAngle: -CGFloat.pi)
    cell.transform = CGAffineTransform(rotationAngle: CGFloat.pi)
    self.setCell(cell: cell, incoming: self.incoming, indexPath: indexPath)

}
return cell
}

    public func setup() {
    bubbleImageView = UIImageView(image: #imageLiteral(resourceName: "chat_bubble_sent"), highlightedImage: #imageLiteral(resourceName: "chat_bubble_sent"))
    bubbleImageView.isUserInteractionEnabled = true

    messageLbl = UILabel(frame: CGRect.zero)
    messageLbl.font = UIFont.systemFont(ofSize: 15)
    messageLbl.numberOfLines = 0
    messageLbl.isUserInteractionEnabled = true
    selectionStyle = .none
    contentView.addSubview(bubbleImageView)
    contentView.addSubview(smavaImg)
    bubbleImageView.addSubview(messageLbl)
    messageLbl.translatesAutoresizingMaskIntoConstraints = false
    bubbleImageView.translatesAutoresizingMaskIntoConstraints = false
    contentView.addConstraint(NSLayoutConstraint(item: bubbleImageView, attribute: .left, relatedBy: .equal, toItem: contentView, attribute: .left, multiplier: 1, constant: 10))
    contentView.addConstraint(NSLayoutConstraint(item: bubbleImageView, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: 4.5))
    bubbleImageView.addConstraint(NSLayoutConstraint(item: bubbleImageView, attribute: .width, relatedBy: .equal, toItem: messageLbl, attribute: .width, multiplier: 1, constant: 30))
    contentView.addConstraint(NSLayoutConstraint(item: bubbleImageView, attribute: .bottom, relatedBy: .equal, toItem: contentView, attribute: .bottom, multiplier: 1, constant: -4.5))

    bubbleImageView.addConstraint(NSLayoutConstraint(item: messageLbl, attribute: .centerX, relatedBy: .equal, toItem: bubbleImageView, attribute: .centerX, multiplier: 1, constant: -2))

    bubbleImageView.addConstraint(NSLayoutConstraint(item: messageLbl, attribute: .centerY, relatedBy: .equal, toItem: bubbleImageView, attribute: .centerY, multiplier: 1, constant: -0.5))
    messageLbl.preferredMaxLayoutWidth = 218
    bubbleImageView.addConstraint(NSLayoutConstraint(item: messageLbl, attribute: .height, relatedBy: .equal, toItem: bubbleImageView, attribute: .height, multiplier: 1, constant: -15))

    contentView.addConstraint(NSLayoutConstraint(item: smavaImg, attribute: .centerX, relatedBy: .equal, toItem: smavaImg, attribute: .centerX, multiplier: 1, constant: -2))

    contentView.addConstraint(NSLayoutConstraint(item: smavaImg, attribute: .centerY, relatedBy: .equal, toItem: smavaImg, attribute: .centerY, multiplier: 1, constant: -0.5))

}

Answer 1

在您的Playground中查看我的git hub项目// Maximo Lucosi： https : //github.com/lucosi/ChatTableView您可以创建具有所有约束的tableViewCell并更改单元格内部的约束。 在您的Playgournd>视图>助手编辑器>显示助手编辑器中打开项目

类MyViewController：UIViewController {

// Messages for test
var messages: [Message] = []

// Table View here + basic configuration
lazy var tableView: UITableView = {
    let view = UITableView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.delegate = self
    view.dataSource = self
    view.backgroundColor = .white
    view.separatorStyle = .none
    return view
}()

override func viewDidLoad() {
    super.viewDidLoad()

    // Set the screen size befor implement layour. NOTICE: Only for playground test
    self.view.frame = frame

    // Messages for test //
    self.messages.append(Message.init(message: "I'm working on a chat app with message bubbles.",
                                      image: UIImage.init(),
                                      incoming: 0))

    self.messages.append(Message.init(message: "What is your dificulte.",
                                      image: UIImage(),
                                      incoming: 1))

    self.messages.append(Message.init(message: "I'm having difficulty getting the chat bubbles to align to the left or right side of the view controller.",
                                      image: UIImage.init(),
                                      incoming: 0))

    self.messages.append(Message.init(message: "One more for me",
                                      image: UIImage(),
                                      incoming: 1))

    self.messages.append(Message.init(message: "I have already implemented a function that redraws UILabels with a passed ratio. So all I need to find is the text in UILabel from my view that would require the maximum ratio to redraw UILabels. So finally I need to do something like this:",
                                      image: UIImage(), incoming: 1))
    // End //


    // Add the tableView
    self.view.addSubview(tableView)

    // Register teh cell in the tableView
    self.tableView.register(ConversationCell.self, forCellReuseIdentifier: cellId)

    // Criate a contraint for the table view
    NSLayoutConstraint.activate(
        [
            tableView.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 44),
            tableView.leftAnchor.constraint(equalTo: self.view.leftAnchor),
            tableView.rightAnchor.constraint(equalTo: self.view.rightAnchor),
            tableView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor)
        ]
    )
}

}

扩展字符串{

//* Calculeta the hight string Function
func calculateTextFrameRect(
    objectsInPlaceHeight: CGFloat,
    objectsInPlaceWidth: CGFloat,
    fontSize: CGFloat,
    fontWeight: CGFloat) -> CGSize
{
    let bounding = CGSize(width: UIScreen.main.bounds.width - objectsInPlaceWidth, height: .infinity)
    let rect = NSString(string: self).boundingRect(
        with: bounding,
        options: NSStringDrawingOptions.usesFontLeading.union(NSStringDrawingOptions.usesLineFragmentOrigin),
        attributes: [NSAttributedStringKey.font: UIFont.systemFont(ofSize: fontSize, weight: UIFont.Weight(rawValue: fontWeight))],
        context: nil)
    return CGSize(width: UIScreen.main.bounds.width, height: rect.height + objectsInPlaceHeight )
}

}

//包含委托和数据源扩展MyViewController的表视图一致：UITableViewDelegate，UITableViewDataSource {

// Change the hight of the cell
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {

    // Calculate the hight of the cell
    let text = self.messages[indexPath.item].message
    let frameSize = text.calculateTextFrameRect(
        objectsInPlaceHeight: 44 + 10,
        objectsInPlaceWidth: 20 + 44 + 20 + self.view.frame.width * 0.4,
        fontSize: UIFont.preferredFont(forTextStyle: UIFontTextStyle.body).pointSize,
        fontWeight: UIFont.Weight.medium.rawValue)
    return frameSize.height
}

// Number os cells
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.messages.count
}

// Return cell to display on the tableView
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! ConversationCell
    cell.messageData = self.messages[indexPath.item]
    return cell

}

}

// ******自定义单元格类****** ////类ConversationCell：UITableViewCell {

var messageData: Message? {
    didSet {
        // Umrap the value incide the cell
        if let message = messageData {

            // Confiture the constraints for cell
            if message.incoming == 0 {
                // Text
                self.messageTextView.textAlignment = .left
                self.bubleImage.backgroundColor = .orange

                // Constraints
                self.lefBubleConstraint.isActive = true
                self.rightBubleConstraint.isActive = false

            } else {
                // Text
                self.messageTextView.textAlignment = .right
                self.bubleImage.backgroundColor = .blue

                // Constraints
                self.lefBubleConstraint.isActive = false
                self.rightBubleConstraint.isActive = true

            }

            if lefBubleConstraint.isActive == true {

                self.leftMessageLable.isActive = true
                self.rightMessageLable.isActive = false

            } else {

                self.leftMessageLable.isActive = false
                self.rightMessageLable.isActive = true

            }

            // Set the data
            self.messageTextView.text = message.message
            self.bubleImage.image = message.image

        }
    }
}

// Create and config the image
let bubleImage: UIImageView = {
    let view = UIImageView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = .blue
    view.layer.cornerRadius = 22
    view.layer.masksToBounds = true
    return view
}()

// Create and config the lable for the text
let messageTextView: UITextView = {
    let view = UITextView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = UIColor.lightGray.withAlphaComponent(0.5)
    view.layer.cornerRadius = 10
    view.textContainerInset = UIEdgeInsetsMake(5, 5, 5, 5)
    view.isUserInteractionEnabled = false
    return view
}()

// Constraints for configuration on didSet data
var lefBubleConstraint: NSLayoutConstraint!
var rightBubleConstraint: NSLayoutConstraint!
var leftMessageLable: NSLayoutConstraint!
var rightMessageLable: NSLayoutConstraint!

// Init the cell with local congiguration
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: nil)

    self.addSubview(bubleImage)
    self.addSubview(messageTextView)

    // Permanent constraints
    NSLayoutConstraint.activate(
        [
            self.bubleImage.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -10),
            self.bubleImage.heightAnchor.constraint(equalToConstant: 44),
            self.bubleImage.widthAnchor.constraint(equalToConstant: 44),

            self.messageTextView.topAnchor.constraint(equalTo: self.topAnchor, constant: 10),
            self.messageTextView.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -10),
            // NOTICE: Use the frame with as parameter for mesure the hight of cell on the main view
            self.messageTextView.widthAnchor.constraint(equalToConstant: self.frame.width * 0.7)
        ]
    )

    // Buble constraint for configuration
    self.lefBubleConstraint = self.bubleImage.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 10)
    self.rightBubleConstraint = self.bubleImage.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -10)

    // Message constrait for congiguration
    self.rightMessageLable = self.messageTextView.rightAnchor.constraint(equalTo: self.bubleImage.leftAnchor, constant: -10)
    self.leftMessageLable = self.messageTextView.leftAnchor.constraint(equalTo: self.bubleImage.rightAnchor, constant: 10)

}
// requerid init
required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

}