xamarin.ios中的单选按钮

Question

如何在xamarin.ios（native）中创建单选按钮？我们不想使用表单方法。

我们尝试使用创建自定义控件，但它无法正常工作。

Answer 1

您可以参考此代码：

这是ViewController.cs：

public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();
        // Perform any additional setup after loading the view, typically from a nib.

        MyRadioButton rBtn = new MyRadioButton (new CGPoint (50, 50), "RadioButton");
        this.Add (rBtn);
    }

这是MyRadioButton.cs：

public class MyRadioButton : UIView
{
    private CircleView circleView;
    private UILabel lbTitle;

    public bool State {
        get {
            return circleView.State;
        }
        set {
            circleView.State = value;
        }
    }

    public MyRadioButton (CGPoint pt,string title)
    {
        this.Frame = new CGRect (pt, new CGSize (150, 30));
        circleView = new CircleView (new CGRect(0, 0, 30, 30));
        lbTitle = new UILabel (new CGRect (30, 0, 120, 30));
        lbTitle.Text = title;
        lbTitle.TextAlignment = UITextAlignment.Center;
        this.AddSubview (circleView);
        this.AddSubview (lbTitle);
        this.BackgroundColor = UIColor.FromRGBA(1,0,0,0.3f);

        UITapGestureRecognizer tapGR = new UITapGestureRecognizer (() => {
            State = !State;
        });
        this.AddGestureRecognizer (tapGR);
    }
}

class CircleView : UIView
{
    private bool state = false;
    public bool State { 
        get {
            return state;
        }
        set {
            state = value;
            this.SetNeedsDisplay ();
        }
    }

    public CircleView (CGRect frame)
    {
        this.BackgroundColor = UIColor.Clear;
        this.Frame = frame;
    }

    public override void Draw (CoreGraphics.CGRect rect)
    {
        CGContext con = UIGraphics.GetCurrentContext ();

        float padding = 5;
        con.AddEllipseInRect (new CGRect (padding, padding, rect.Width - 2 * padding, rect.Height - 2 * padding));
        con.StrokePath ();

        if (state) {
            float insidePadding = 8;
            con.AddEllipseInRect (new CGRect (insidePadding, insidePadding, rect.Width - 2 * insidePadding, rect.Height - 2 * insidePadding));
            con.FillPath ();
        }
    }
}

希望它可以帮到你。

Answer 2

与Xamarin.iOS一起使用的BEMCheckBox库（请参阅https://github.com/saturdaymp/XPlugins.iOS.BEMCheckBox获取nuget包）提供单选按钮功能：https://github.com/Boris-Em/BEMCheckBox#group--radio-button-functionality

Answer 3

在iOS中，我们只能通过自定义来实现。我们可以在需要管理按钮上的动作和图像的一门课上讲，这看起来像单选b按钮。 下面是我们如何制作单选按钮的示例：

公共类OoRadioButtonView：OoBaseSelectionView

{
    public OoRadioButtonView(bool hasTextField = false) : base(hasTextField)
    {
        _markSize = 11;

        CheckMark = new RoundCornersView()
        {
            roundedCornerRadius = (_checkMarkSize / 2),
            RoundedBottomLeftRadius = true,
            RoundedBottomRightRadius = true,
            RoundedTopLeftRadius = true,
            RoundedTopRightRadius = true,

            BackgroundColor = ColorConverter.FromHex(PclColors.Background.LightLightGray),

            borderWidth = 2,
            borderColor = ColorConverter.FromHex(PclColors.Common.DarkGray),
            BorderRadius = (_checkMarkSize / 2)
        };
        Add(CheckMark);

        Mark = new RoundCornersView()
        {
            roundedCornerRadius = (_markSize / 2),
            RoundedBottomLeftRadius = true,
            RoundedBottomRightRadius = true,
            RoundedTopLeftRadius = true,
            RoundedTopRightRadius = true,

            BackgroundColor = Colors.MAIN_RED,

            Hidden = true
        };
        Add(Mark);

        CreateCheckMarkConstraints();
    }
}

下面是我在上面的类中继承的抽象类

公共抽象类OoBaseSelectionView：UIView，INotifyPropertyChanged

{
    public bool IsSelected
    {
        get
        {
            if (Mark != null)
                return !Mark.Hidden;

            return false;
        }
    }

    public int Value { get; set; }

    public RoundCornersView CheckMark { get; set; }
    public UIView Mark { get; set; }
    public UILabel OptionLabel { get; set; }
    public UILabel SecondaryLabel { get; set; }

    public UITextField TextField { get; set; }

    public string TextFieldHint
    {
        get
        {
            return TextField.Placeholder;
        }
        set
        {
            TextField.Placeholder = value;

        }
    }

    string _text;
    public string Text
    {
        get
        {
            return _text;
        }
        set
        {
            _text = value;

            TextField.Text = _text;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Text"));
        }
    }

    protected float _checkMarkSize;
    protected float _markSize;

    public event PropertyChangedEventHandler PropertyChanged;

    public bool HasTextFiled { get; private set; }

    protected OoBaseSelectionView(bool hasTextFiled)
    {
        HasTextFiled = hasTextFiled;

        _checkMarkSize = 22;

        CreateViews();
        CreateConstraints();
    }

    void CreateViews()
    {
        OptionLabel = new UILabel()
        {
            TextColor = Colors.TEXT_BLACK_COLOR,
            Font = UIFont.FromName(Fonts.FONT_NOTO_SANS, 14f),
            Lines = 2
        };
        Add(OptionLabel);

        SecondaryLabel = new UILabel()
        {
            TextColor = Colors.TEXT_BLACK_COLOR,
            Font = UIFont.FromName(Fonts.FONT_NOTO_SANS, 14f),
            TextAlignment = SettingsManager.IsLTR ? UITextAlignment.Right : UITextAlignment.Left
        };
        Add(SecondaryLabel);

        if (HasTextFiled)
        {
            TextField = new UITextField();
            TextField.Layer.CornerRadius = 10;
            TextField.Layer.BorderWidth = 1;
            TextField.UserInteractionEnabled = false;
            TextField.TextAlignment = UITextAlignment.Center;
            TextField.Layer.BorderColor = UIColor.Black.CGColor;
            TextField.LeftView = new UIView(new CoreGraphics.CGRect(0, 0, 10, 10));
            TextField.LeftViewMode = UITextFieldViewMode.Always;
            Add(TextField);
        }
    }

    void CreateConstraints()
    {
        this.SubviewsDoNotTranslateAutoresizingMaskIntoConstraints();
        this.AddConstraints(
            OptionLabel.AtTopOf(this, Dimensions.GLOBAL_MARGIN_SMALL),

            SecondaryLabel.AtTopOf(this, Dimensions.GLOBAL_MARGIN_SMALL),
            SecondaryLabel.AtTrailingOf(this, Dimensions.GLOBAL_MARGIN_MEDIUM)
        );

        this.AddConstraints(OptionLabel.ToLeadingOf(SecondaryLabel, Dimensions.GLOBAL_MARGIN_EXTRASMALL));

        if (HasTextFiled)
        {
            this.AddConstraints(
                TextField.WithSameCenterX(this),
                TextField.Below(OptionLabel, Dimensions.GLOBAL_MARGIN_SMALL),
                TextField.Width().EqualTo(150),
                TextField.Height().EqualTo(35),
                TextField.AtBottomOf(this)
            );
        }
        else
        {
            this.AddConstraints(
                OptionLabel.AtBottomOf(this, Dimensions.GLOBAL_MARGIN_SMALL),
                SecondaryLabel.AtBottomOf(this, Dimensions.GLOBAL_MARGIN_SMALL)
            );
        }
    }

    public void CreateCheckMarkConstraints()
    {
        this.SubviewsDoNotTranslateAutoresizingMaskIntoConstraints();
        this.AddConstraints(
            CheckMark.AtLeadingOf(this, Dimensions.GLOBAL_MARGIN_MEDIUM),
            CheckMark.WithSameCenterY(OptionLabel),
            CheckMark.Height().EqualTo(_checkMarkSize),
            CheckMark.Width().EqualTo(_checkMarkSize),

            Mark.Height().EqualTo(_markSize),
            Mark.Width().EqualTo(_markSize),
            Mark.WithSameCenterX(CheckMark),
            Mark.WithSameCenterY(CheckMark)
        );

        if (LangUtils.IsArabic)
            this.AddConstraints(OptionLabel.ToLeftOf(CheckMark, Dimensions.GLOBAL_MARGIN_SMALL));

        else
            this.AddConstraints(OptionLabel.ToRightOf(CheckMark, Dimensions.GLOBAL_MARGIN_SMALL));
    }

    public void UnSelect()
    {
        if (Mark != null)
            Mark.Hidden = true;

        if (HasTextFiled)
        {
            TextField.UserInteractionEnabled = false;
            TextField.Text = null;
        }
    }

    public void Select()
    {
        if (Mark != null)
            Mark.Hidden = false;

        if (HasTextFiled)
        {
            TextField.UserInteractionEnabled = true;
            TextField.BecomeFirstResponder();
        }
    }

    public void Toggle()
    {
        if (Mark != null)
            Mark.Hidden = !Mark.Hidden;
    }

    public void SetOptionLabel(string option)
    {
        OptionLabel.Text = option;
    }

    public void SetSecondaryLabel(string secondary)
    {
        SecondaryLabel.Text = secondary;
    }

    public string GetTextFieldString()
    {
        return TextField.Text ?? string.Empty;
    }

}

Answer 4

在Xamarin IOS中，单选按钮只有两个选项。您可以使用选择器视图，其作用类似于单选按钮，因为它只允许您选择一个选项。但是，如果你真的想要单选按钮的外观，你可以使用WKWebView并在html中构建表单，然后有一段代码从webview中获取单选按钮状态，并预先形成你需要完成的任何操作。