ios - 如何通过自动布局以编程方式添加 InputAccessoryView？

Question

我正在尝试添加带有“完成”按钮的 UIView 作为文本字段的输入附件 View 。

        let view = UIView()
        let doneButton = UIButton(type: .Custom)
        doneButton.setTitle("Done", forState: .Normal)
        doneButton.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(doneButton)
        view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:[button]-|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: ["button":doneButton]))
        view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[button]|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: ["button":doneButton]))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: doneButton, attribute: NSLayoutAttribute.Height, multiplier: 1, constant: 0)) // Even this does not work
        self.emailTextField.inputAccessoryView = view

但是我看不到正在设置的 View 高度，也看不到 Xcode 中的 View 层次调试器/检查器中的按钮。

但是如果我通过设置其框架来添加 View ，我可以看到正在添加的 View 。我还尝试将高度约束强制设置为常量 21，它打破了一些我没有添加的其他约束 _UIKBAutolayoutHeightConstraint

"<NSLayoutConstraint:0x7fa3c962be50 UIView:0x7fa3c963bf60.height == UIButton:0x7fa3c963c0d0.height + 21>",
    "<NSLayoutConstraint:0x7fa3c95e0a90 '_UIKBAutolayoutHeightConstraint' V:[UIView:0x7fa3c963bf60(0)]>"

有人遇到过这个问题吗？

Answer 1

swift 3+

1. 您需要在第一行指定工具栏 View 的大小。

2. 不要在 viewcontroller 类中使用“view”作为变量，因为它会造成与 self.view 的混淆

   override func viewDidLoad() {
       super.viewDidLoad()
       let toolBar = UIView(frame: CGRect(x: 0, y: 0, width: view.bounds.width, height: 50))
       toolBar.backgroundColor = .gray
       let doneButton = UIButton(type: .custom)
       doneButton.setTitle("Done", for: .normal)
       doneButton.translatesAutoresizingMaskIntoConstraints = false
       toolBar.addSubview(doneButton)
       toolBar.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[button]-|", 
                                                             options: .directionLeadingToTrailing, 
                                                             metrics: nil, 
                                                             views: ["button":doneButton]))
       toolBar.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[button]|", 
                                                             options: .directionLeadingToTrailing, 
                                                             metrics: nil, 
                                                             views: ["button":doneButton]))
       self.emailTextField.inputAccessoryView = toolBar 
   }