如果你有多个数字字段，我建议子类化UITextField来创建一个NumericTextField，它总是显示一个带有done按钮的数字键盘。然后，简单地将你的数值字段与接口构建器中的这个类关联起来，你就不需要在任何视图控制器中添加任何额外的代码。下面是我在Xcode 8.0中使用的Swift 3.0类。

class NumericTextField: UITextField {
   let numericKbdToolbar = UIToolbar()

    // MARK: Initilization
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.initialize()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.initialize()
    }

    // Sets up the input accessory view with a Done button that closes the keyboard
    func initialize()
    {
        self.keyboardType = UIKeyboardType.numberPad

        numericKbdToolbar.barStyle = UIBarStyle.default
        let space = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
        let callback = #selector(NumericTextField.finishedEditing)
        let donebutton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.done, target: self, action: callback)
        numericKbdToolbar.setItems([space, donebutton], animated: false)
        numericKbdToolbar.sizeToFit()
        self.inputAccessoryView = numericKbdToolbar
    }

    // MARK: On Finished Editing Function
    func finishedEditing()
    {
        self.resignFirstResponder()
    }
}

斯威夫特4.2

class NumericTextField: UITextField {
    let numericKbdToolbar = UIToolbar()

    // MARK: Initilization
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.initialize()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.initialize()
    }

    // Sets up the input accessory view with a Done button that closes the keyboard
    func initialize()
    {
        self.keyboardType = UIKeyboardType.numberPad

        numericKbdToolbar.barStyle = UIBarStyle.default
        let space = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: nil, action: nil)
        let callback = #selector(NumericTextField.finishedEditing)
        let donebutton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.done, target: self, action: callback)
        numericKbdToolbar.setItems([space, donebutton], animated: false)
        numericKbdToolbar.sizeToFit()
        self.inputAccessoryView = numericKbdToolbar
    }

    // MARK: On Finished Editing Function
    @objc func finishedEditing()
    {
        self.resignFirstResponder()
    }
}

一个更简单的解决方案

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    [super touchesBegan:touches withEvent:event];

    [textViewInstance1 resignFirstResponder];
    [textViewInstance2 resignFirstResponder];
    [textField resignFirstResponder];
}

以下是对Luda的回答的全面检查，并进行了以下更改:

附件视图会自动调整到应用程序框架的宽度 避免使用已弃用的常量UIBarButtonItemStyleBordered Done按钮被实例化为UIBarButtonSystemItemDone

目前“Done”按钮位于附件视图的中央。您可以通过删除相关一侧的空格将其定位在左侧或右侧。

我省略了“取消”按钮，因为默认键盘也没有这个按钮。如果你确实想要一个“取消”按钮，我建议你实例化它为一个UIBarButtonSystemItemCancel，并确保你没有丢弃文本字段中的原始值。在Luda的回答中实现的“取消”行为会用空字符串覆盖值，这可能不是你想要的。

- (void)viewDidLoad {
  [super viewDidLoad];
  float appWidth = CGRectGetWidth([UIScreen mainScreen].applicationFrame);
  UIToolbar *accessoryView = [[UIToolbar alloc]
                              initWithFrame:CGRectMake(0, 0, appWidth, 0.1 * appWidth)];
  UIBarButtonItem *space = [[UIBarButtonItem alloc]
                            initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                            target:nil
                            action:nil];
  UIBarButtonItem *done = [[UIBarButtonItem alloc]
                           initWithBarButtonSystemItem:UIBarButtonSystemItemDone
                           target:self
                           action:@selector(selectDoneButton)];
  accessoryView.items = @[space, done, space];
  self.valueField.inputAccessoryView = accessoryView;
}

- (void)selectDoneButton {
  [self.valueField resignFirstResponder];
}

有关构建附件视图的更多信息，请参阅Apple关于数据输入自定义视图的文档。你可能会想要参考UIToolbar和UIBarButtonItem的参考页面。

 let pickerView = UIPickerView()
   
 var yearpickerToolbar: UIToolbar?
   
    func createPickerView() {
          
           pickerView.delegate = self
           textfield.inputView = pickerView }
   
   
     func dismissPickerView() {
           let toolBar = UIToolbar()
           toolBar.sizeToFit()
   
           toolBar.isUserInteractionEnabled = true
           textfield.inputAccessoryView = toolBar
           textfield.delegate = self
   
   
   yearpickerToolbar = UIToolbar()
           yearpickerToolbar?.autoresizingMask = .flexibleHeight
   
           //add buttons
           let cancelButton = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action:#selector(cancelBtnClicked(_:)))
           cancelButton.tintColor = UIColor.blue
           let flexSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
           
           let doneButton = UIBarButtonItem(title: "Done", style: .plain , target: self, action: #selector(self.doneBtnClicked(_ :) ))
           doneButton.tintColor = UIColor.blue
   
           doneButton.setTitleTextAttributes([NSAttributedString.Key.foregroundColor:
   UIColor.black], for: .normal)
           cancelButton.setTitleTextAttributes([NSAttributedString.Key.foregroundColor:
   UIColor.black], for: .normal)
           
           yearpickerToolbar?.items = [cancelButton, flexSpace, doneButton]
           textfield.inputAccessoryView = yearpickerToolbar }
   
   @objc func cancelBtnClicked(_ button: UIBarButtonItem?) {
           self.view.endEditing(true)
           
       }
   
       @objc func doneBtnClicked(_ button: UIBarButtonItem?) {
           self.view.endEditing(true)
       }

我在这里描述了iOS 4.2+的一个解决方案，但键盘出现后，解散按钮会消失。这并不可怕，但也不理想。

上面链接的问题中描述的解决方案包括一种更优雅的消除按钮的错觉，我将按钮淡出并垂直移动，以提供键盘和按钮一起消除的外观。

如果我们告诉视图控制器的视图结束编辑，我们也可以让“user touched somewhere else”解决方案更简单:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
 { 
      [super touchesBegan:touches withEvent:event];

      [self.view endEditing:YES]; //YES ignores any textfield refusal to resign
 }

．.． 假设“触摸其他地方会取消键盘”是视图中任何其他可编辑字段所期望的行为。