ios - 更改 UIToolBar 的 NSConstraints 时应用程序崩溃

Question

本质上，我试图在选择文本字段后在键盘上方显示 UIToolBar。

选择要编辑的文本字段时出现以下错误:

Terminating app due to uncaught exception 'NSGenericException', reason: 'Unable to activate constraint with anchors and because they have no common ancestor. Does the constraint or its anchors reference items in different view hierarchies? That's illegal.'

在 viewDidLoad 中我执行以下操作:

let toolBar = UIToolbar()
var items = [UIBarButtonItem]()

items.append(
    UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
)

items.append(
    UIBarButtonItem(title: "Tool Bar Text", style: .plain, target: self, action: #selector(confirmSignature))
)

items.append(
    UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
)

toolBar.setItems(items, animated: true)
toolBar.tintColor = .white
toolBar.barTintColor = UIColor.red



toolBar.translatesAutoresizingMaskIntoConstraints = false


if #available(iOS 11.0, *) {
    let guide = self.view.safeAreaLayoutGuide
    toolBar.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
    toolBar.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
    toolBar.bottomAnchor.constraint(equalTo: guide.bottomAnchor).isActive = true
    toolBar.heightAnchor.constraint(equalToConstant: 80).isActive = true

}
else {
    NSLayoutConstraint(item: toolBar, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1.0, constant: 0).isActive = true
    NSLayoutConstraint(item: toolBar, attribute: .leading, relatedBy: .equal, toItem: view, attribute: .leading, multiplier: 1.0, constant: 0).isActive = true
    NSLayoutConstraint(item: toolBar, attribute: .trailing, relatedBy: .equal, toItem: view, attribute: .trailing, multiplier: 1.0, constant: 0).isActive = true

    toolBar.heightAnchor.constraint(equalToConstant: 44).isActive = true
}

exampleTextField.inputAccessoryView = toolBar

作为扩展，我在选择文本字段时执行以下操作:

extension myTableViewName: UITextFieldDelegate {
    func textFieldDidBeginEditing(_ textField: UITextField) {
        if textField == exampleTextField {
            let toolBar = UIToolbar()

            view.addSubview(toolBar)
        }
    }
}

Answer 1

注释这些行(文本字段附件和 View 之间没有共同的 View )

let guide = self.view.safeAreaLayoutGuide
toolBar.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
toolBar.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
toolBar.bottomAnchor.constraint(equalTo: guide.bottomAnchor).isActive = true

由于工具栏输入 View 将始终占据底部屏幕的整个宽度和指定的高度，因此您只能保留此

toolBar.heightAnchor.constraint(equalToConstant: 80).isActive = true