如果 UITextField 是子視圖，則不會調用 becomeFirstResponder

Question

我對UITextField有一個奇怪的問題：

class AnnotateTextField: UIView {

    // MARK: - Views

    let textField = UITextField()

    // MARK: - Initializers

    init() {
        super.init(frame: .zero)

        setupViews()
    }

    @available(*, unavailable)
    private override init(frame: CGRect) {
        fatalError("init(frame:) has not been implemented")
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: - Setup

    private func setupViews() {
        let textField = UITextField()
        textField.font = UIFont.systemFont(ofSize: 100.0)
        textField.textColor = .white

        backgroundColor = .black.withAlphaComponent(0.7)
        clipsToBounds = true
        layer.cornerRadius = 16.0
        // Paint stays behind it
        layer.zPosition = 1

        addSubview(textField)
        textField.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(16.0)
        }
    }

}

如果我將此添加到我的視圖並調用becomesFirstResponder鍵盤將不會顯示：

private func addText() {
    let annotateTextField = AnnotateTextField()

    addSubview(annotateTextField)
    annotateTextField.snp.makeConstraints { make in
        make.center.equalToSuperview()
    }

    annotateTextField.textField.becomeFirstResponder()
}

但是對於常規UITextField它工作正常：

private func addText() {
    let text = UITextField()
    addSubview(text)
    // This shows the keyboard
    text.becomeFirstResponder()
}

我在這里做錯了什么？ 我嘗試在AnnotateTextField上啟用用戶交互，但並沒有什么不同。

Answer 1

我認為問題在於setupViews函數。 您正在該函數中創建一個新的文本字段對象，並在此文本字段上進行更改並將其添加到視圖中。

要解決此問題，請在函數內刪除新的 texfield 對象，例如：

 private func setupViews() {

    textField.font = UIFont.systemFont(ofSize: 100.0)
    textField.textColor = .white

    backgroundColor = .black.withAlphaComponent(0.7)
    clipsToBounds = true
    layer.cornerRadius = 16.0
    // Paint stays behind it
    layer.zPosition = 1

    addSubview(textField)
    textField.snp.makeConstraints { make in
        make.edges.equalToSuperview().inset(16.0)
    }
}

或將類中的文本字段對象與您在此函數中創建的對象相等，例如

 private func setupViews() {
    let textField = UITextField()

    textField.font = UIFont.systemFont(ofSize: 100.0)
    textField.textColor = .white

    backgroundColor = .black.withAlphaComponent(0.7)
    clipsToBounds = true
    layer.cornerRadius = 16.0
    // Paint stays behind it
    layer.zPosition = 1
    self.textField = textField // add this
    addSubview(self.textField) // change this
    textField.snp.makeConstraints { make in
        make.edges.equalToSuperview().inset(16.0)
    }
}

annotateTextField.textField 的框架為零，因為您正在創建一個新的文本字段，並且您正在函數中設置對該文本字段的約束