除非我滚动，否则页脚不会显示在 TableView 上

Question

我向我的TableView 添加了一个页脚，它显示在视图的底部。但是，除非我向下滚动，否则页脚不可见，然后它会显示出来。

这就是我要说的：

我还没有填写TableView，但我认为这不是问题。这是我为页脚编写的代码：

func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return 50
}

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

    footerView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(footerView)

    //x, y, w, h constraints
    footerView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    footerView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
    footerView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
    footerView.heightAnchor.constraint(equalToConstant: 50).isActive = true

    //Send Button
    let sendButton = UIButton(type: .system)
    sendButton.setTitle("Send", for: .normal)
    sendButton.translatesAutoresizingMaskIntoConstraints = false
    sendButton.addTarget(self, action: #selector(handleSend), for: .touchUpInside)
    footerView.addSubview(sendButton)

    //x, y, w, h Button constraints
    sendButton.rightAnchor.constraint(equalTo: footerView.rightAnchor).isActive = true
    sendButton.centerYAnchor.constraint(equalTo: footerView.centerYAnchor).isActive = true
    sendButton.widthAnchor.constraint(equalToConstant: 80).isActive = true
    sendButton.heightAnchor.constraint(equalTo: footerView.heightAnchor).isActive = true

    //Text Field
    footerView.addSubview(inputTextField)

    //x, y, w, h Text Field constraints
    inputTextField.leftAnchor.constraint(equalTo: footerView.leftAnchor, constant: 8).isActive = true
    inputTextField.centerYAnchor.constraint(equalTo: footerView.centerYAnchor).isActive = true
    inputTextField.rightAnchor.constraint(equalTo: sendButton.leftAnchor).isActive = true
    inputTextField.heightAnchor.constraint(equalTo: footerView.heightAnchor).isActive = true

    // Separator
    let separatorLineView = UIView()
    separatorLineView.backgroundColor = UIColor(red: CGFloat(220/255), green: CGFloat(220/255), blue: CGFloat(220/255), alpha: 0.1)
    separatorLineView.translatesAutoresizingMaskIntoConstraints = false
    footerView.addSubview(separatorLineView)

    //x, y, w, h separator constraints
    separatorLineView.leftAnchor.constraint(equalTo: footerView.leftAnchor).isActive = true
    separatorLineView.topAnchor.constraint(equalTo: footerView.topAnchor).isActive = true
    separatorLineView.widthAnchor.constraint(equalTo: footerView.widthAnchor).isActive = true
    separatorLineView.heightAnchor.constraint(equalToConstant: 1).isActive = true

    return footerView
}

我希望页脚的工作方式是在用户导航到视图时立即显示，然后在键盘显示时向上移动，并在键盘关闭时向下移动。

Answer 1

您不应将footerView 作为子视图添加到另一个UIView。

您应该删除以下代码：

footerView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(footerView)

    //x, y, w, h constraints
    footerView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
    footerView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
    footerView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
    footerView.heightAnchor.constraint(equalToConstant: 50).isActive = true

UITableView 将处理页脚视图的放置。

如果我怀疑您打算将footerView 固定到视图的底部，那么您不应该将其作为表格视图的页脚视图返回。它应该与UITableView 层次结构分开。