swift - 更改 iOS 中 TableviewCell 的左右填充

Question

我正在尝试制作一个气泡UITableviewCell。单元格有一个 UILabel，所有 edges 都固定到单元格 ContentView 的边缘，并且 UITableView 使用 AutomaticHeight (基于Label.text)我已将CellBackgroundView图像设置为下面的函数

func changeImage(_ name: String) -> UIImage? {
        guard let image = UIImage(named: name) else { return nil }
        return image.resizableImage(withCapInsets: UIEdgeInsets(top: 17, left: 30, bottom: 17, right: 30), resizingMode: .stretch).withRenderingMode(.alwaysTemplate)
    } 

上面的函数在cellforRowAtIndexPath中调用:

cell.backgroundView = UIImageView(image: changeImage("right_bubble"))

我的背景图像看起来像气泡:

问题是我无法更改 Cell 的左侧或右侧 padding。有没有办法更改填充(可能是左或右)(以区分发送者和接收者)或需要从 UITableView 更改为 UICollectionView？

编辑

我提出了一个在自定义单元子类中动态更改约束的解决方案。下面是子类的实现

import UIKit

enum Direction {
    case left
    case right
}

class MessageCell: UITableViewCell {
    
    @IBOutlet weak var backgroundImageView: UIImageView!
    
    @IBOutlet weak var messageText: UILabel!
    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }
    
    override func prepareForReuse() {
        self.layoutIfNeeded()
    }

    func configureCell(with message: Message, direction: Direction ) {
        self.messageText?.text = message.text
        
        switch direction {
        case .left:
            backgroundImageView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
            contentView.trailingAnchor.constraint(greaterThanOrEqualTo: backgroundImageView.trailingAnchor, constant: 50).isActive = true
            self.backgroundImageView.image = UIImage.changeImage("left_bubble")
            self.backgroundImageView.tintColor = .lightGray
        case .right:
            backgroundImageView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true
            backgroundImageView.leadingAnchor.constraint(greaterThanOrEqualTo: contentView.leadingAnchor, constant: 50).isActive = true
            self.backgroundImageView.image = UIImage.changeImage("right_bubble")
            self.backgroundImageView.tintColor = .blue
        }
        self.layoutIfNeeded()
    }

}

但是当行数超过屏幕高度并需要滚动时，自动布局会遇到问题。以下是错误:

2018-11-03 19:53:36.478275+0800 VicGithubDM[2352:34611] [LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x6000006e9090 V:|-(10)-[UILabel:0x7fe37dd3bb70'still have some bugs stil...']   (active, names: '|':UITableViewCellContentView:0x7fe37dd3b750 )>",
    "<NSLayoutConstraint:0x6000006ea620 V:[UILabel:0x7fe37dd3bb70'still have some bugs stil...']-(10)-|   (active, names: '|':UITableViewCellContentView:0x7fe37dd3b750 )>",
    "<NSLayoutConstraint:0x6000006e1d10 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x7fe37dd3b750.height == 1.19209e-07   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000006ea620 V:[UILabel:0x7fe37dd3bb70'still have some bugs stil...']-(10)-|   (active, names: '|':UITableViewCellContentView:0x7fe37dd3b750 )>  

Answer 1

我建议创建一个自定义单元格并根据类型更改约束值。