Question

我已根据此处的示例创建了UILabel的子类：UILabel doesn't show inputView。我试图在UITableViewCell的子类中创建一个标签实例。我遇到的问题是，要创建一个DatePickerLabel实例，它需要一个NSCoder。

let dp = DatePickerLabel(coder: NSCoder)

我在我的类中有UITableViewCell的子类，但它似乎永远不会被触发，当我运行它时会导致空指针（我尝试使用变量然后在此代码中分配它）：

required public init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    print("triggered")
}

非常感谢任何帮助，DatePickerLabel如下所示！

class DatePickerLabel: UILabel {

private let _inputView: UIView? = {
    let picker = UIDatePicker()
    return picker
}()

private let _inputAccessoryToolbar: UIToolbar = {
    let toolBar = UIToolbar()
    toolBar.barStyle = UIBarStyle.default
    toolBar.isTranslucent = true
    toolBar.sizeToFit()
    return toolBar
}()

override var inputView: UIView? {
    return _inputView
}

override var inputAccessoryView: UIView? {
    return _inputAccessoryToolbar
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)

    let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.plain, target: self, action: #selector(doneClick))
    let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)

    _inputAccessoryToolbar.setItems([ spaceButton, doneButton], animated: false)

    let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(launchPicker))
    self.addGestureRecognizer(tapRecognizer)
}

override var canBecomeFirstResponder: Bool {
    return true
}

@objc private func launchPicker() {
    becomeFirstResponder()
}

@objc private func doneClick() {
    resignFirstResponder()
}

}

干杯！

Answer 1

在您链接的问题中，初始化函数为initWithCoder，因为它用于从故事板或笔尖加载视图。你不这样做。

因此，将init更改为“普通”，例如：

init() {
    super.init()

    ...
}

创建需要NSCoder的子类实例

1 个答案: