如何通过选择器设置 textField becomeFirstResponder

Question

我写了一个 UITextfield 扩展来构建我自己的自定义输入工具栏：

func addToolbar(selector: Selector? = nil) {
    let action = selector == nil ? #selector(resignFirstResponder) : selector
    
    let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    let doneButton = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: action)

    let toolbar = UIToolbar()
    toolbar.items = [flexibleSpace, doneButton]
    toolbar.sizeToFit()
    toolbar.layoutIfNeeded()
    
    inputAccessoryView = toolbar
    returnKeyType = .done
}

我是这样用的：

let myPickerView = UIPickerView()
myPickerView.dataSource = myPickerViewBehavior
myPickerView.delegate = myPickerViewBehavior
    
if let selected = value {
    let selectedIndex = PickableItemType.index(of: selected.rawValue)
    myPickerView.selectRow(selectedIndex, inComponent: 0, animated: true)
}
    
myTextField.delegate = self
myTextField.inputView = myPickerView
myTextField.addToolbar(selector: #selector(nextTextField.becomeFirstResponder))

正如您想象的那样，我希望在用户按下工具栏中的完成后出现下一个 UITextField 到 becomeFirstResponder。但什么也没发生。为了进行测试，我尝试在内部使用一个简单的 @objs func 和 print 语句 and/or nextTextField.becomeFirstResponder，结果相同。我也试过使用 UITapGestureRecognizer 和 #selector(nextTextField.becomeFirstResponder)，也是同样的结果。

所以我猜这与代码无法运行的#selector 机制有关。

P.S：如果 selector == nil 在 addToolbar 内，#selector(resignFirstResponder) 工作正常。

Answer 1

我认为问题是由于 target: 设置 doneButton 错误造成的。

如果您还在 addToolbar: 方法中提供目标，例如：

func addToolbar(target: Any? = nil, selector: Selector? = nil) {
    let object = target ?? self
    let action = selector ?? #selector(resignFirstResponder)
    
    let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    let doneButton = UIBarButtonItem(barButtonSystemItem: .done, target: object, action: action)

    let toolbar = UIToolbar()
    toolbar.items = [flexibleSpace, doneButton]
    toolbar.sizeToFit()
    toolbar.layoutIfNeeded()
    
    inputAccessoryView = toolbar
    returnKeyType = .done
}

这应该有效：

firstTextField.addToolbar(target: secondTextField, selector: #selector(becomeFirstResponder))

这是一个小测试结果：

https://imgur.com/R7R1ee9

如何通过选择器设置 textField becomeFirstResponder

How to set textField becomeFirstResponder via selector

swift

uitextfield

selector

becomefirstresponder

inputview