swift - 如何以编程方式向两个 UI 项目(标签和按钮？

Question

理想情况下，我希望标签和按钮如下所示:

如何以编程方式设置约束？目前我拥有的代码是:

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {

        let frame: CGRect = tableView.frame

        let label: UILabel = {
            let lb = UILabel()
            lb.translatesAutoresizingMaskIntoConstraints = false
            lb.text = "@\(userM) \(postM)"
            lb.font = lb.font.withSize(14)
            lb.textColor = .black
            lb.backgroundColor = .white
            lb.numberOfLines = 0
            return lb
        }()

        let button = UIButton(frame: CGRect(x: 100, y: 100, width: 100, height: 25))
        button.backgroundColor = .blue
        button.setTitle("Answer", for: .normal)
        button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)


        let header: UIView = {
            let hd = UIView()
            hd.addSubview(label)
            hd.addSubview(button)
            label.leadingAnchor.constraint(equalTo: hd.leadingAnchor, constant: 10).isActive = true
            label.topAnchor.constraint(equalTo: hd.topAnchor, constant: 10).isActive = true
            label.trailingAnchor.constraint(equalTo: hd.trailingAnchor, constant: -10).isActive = true
            label.bottomAnchor.constraint(equalTo: hd.bottomAnchor, constant: -10).isActive = true

            return hd
        }()

        return header

    }

但是，代码返回的按钮距离屏幕太远，而且格式不正确。我需要在按钮上设置哪些附加约束才能使其位于动态 TextView 的底部并与 UILabel 的左侧对齐？

Answer 1

您没有为按钮设置约束。将以下行添加到为 label 设置约束的 block 中:

button.leadingAnchor.constraint(equalTo: hd.leadingAnchor, constant: 10).isActive = true
button.topAnchor.constraint(equalTo: label.bottomAnchor, constant: -10).isActive = true
button.widthAnchor.constraint(equalToConstant: 100).isActive = true
button.bottomAnchor.constraint(equalTo: hd.bottomAnchor, constant: -10).isActive = true

删除label.bottomAnchor.constraint(equalTo: hd.bottomAnchor,constant: -10).isActive = true，你不需要这个约束。

不要忘记实现 func tableView(_ tableView: UITableView,estimatedHeightForHeaderInSection section: Int) -> CGFloat 和 func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat，需要确定表头高度:

func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return UITableView.automaticDimension
}

func tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat {
    return 100
}