How do I display the standard checkmark on a UICollectionViewCell?

Question

I\'m designing an iOS app with a UICollectionView, and I\'d like users to be able to select multiple items within this view. It seems there\'s a standard style of checkmark

Answer 1

C# version of the same code

public class CheckMarkView : UIView
{
    private bool _checked;
    private CheckMarkStyle _checkMarkStyle;

    public CheckMarkView()
    {
        Opaque = false;
    }

    public bool Checked
    {
        get
        {
            return _checked;
        }
        set
        {
            _checked = value;
            SetNeedsDisplay();
        }
    }

    public CheckMarkStyle CheckMarkStyle
    {
        get
        {
            return _checkMarkStyle;
        }
        set
        {
            _checkMarkStyle = value;
            SetNeedsDisplay();
        }
    }

    public override void Draw(CGRect rect)
    {
        if (Checked)
            DrawRectChecked(rect);
        else if (CheckMarkStyle == CheckMarkStyle.OpenCircle)
            DrawRectOpenCircle(rect);
        else if (CheckMarkStyle == CheckMarkStyle.GrayedOut)
            DrawRectGrayedOut(rect);
    }


    private void DrawRectChecked(CGRect rect)
    {
        var context = UIGraphics.GetCurrentContext();

        var checkmarkBlue2 = UIColor.FromRGBA(0.078f, 0.435f, 0.875f, 1f);

        // Shadow Declarations
        var shadow2 = UIColor.Brown;
        var shadow2Offset = new CGSize(0.1, -0.1);
        nfloat shadow2BlurRadius = 2.5f;

        var frame = Bounds;

        // Subframes
        var group = new CGRect(frame.GetMinX() + 3, frame.GetMinY() + 3, frame.Width - 6, frame.Height - 6);


        // CheckedOval Drawing
        var checkedOvalPath = UIBezierPath.FromOval(new CGRect(group.GetMinX() + Math.Floor(group.Width * 0.00000 + 0.5), group.GetMinY() + Math.Floor(group.Height * 0.00000 + 0.5), Math.Floor(group.Width * 1.00000 + 0.5) - Math.Floor(group.Width * 0.00000 + 0.5), Math.Floor(group.Height * 1.00000 + 0.5) - Math.Floor(group.Height * 0.00000f + 0.5f)));
        context.SaveState();
        context.SetShadow(shadow2Offset, shadow2BlurRadius, shadow2.CGColor);
        checkmarkBlue2.SetFill();
        checkedOvalPath.Fill();
        context.RestoreState();

        UIColor.White.SetStroke();
        checkedOvalPath.LineWidth = 1;
        checkedOvalPath.Stroke();


        // Bezier Drawing
        var bezierPath = new UIBezierPath();
        bezierPath.MoveTo(new CGPoint(group.GetMinX() + 0.27083f * group.Width, group.GetMinY() + 0.54167f * group.Height));
        bezierPath.AddLineTo(new CGPoint(group.GetMinX() + 0.41667f * group.Width, group.GetMinY() + 0.68750f * group.Height));
        bezierPath.AddLineTo(new CGPoint(group.GetMinX() + 0.75000f * group.Width, group.GetMinY() + 0.35417f * group.Height));
        bezierPath.LineCapStyle = CGLineCap.Square;

        UIColor.White.SetStroke();
        bezierPath.LineWidth = 1.3f;
        bezierPath.Stroke();
    }

    private void DrawRectGrayedOut(CGRect rect)
    {
        var context = UIGraphics.GetCurrentContext();

        var grayTranslucent = UIColor.FromRGBA(1, 1, 1, 0.6f);

        // Shadow Declarations
        var shadow2 = UIColor.Black;
        var shadow2Offset = new CGSize(0.1, -0.1);
        nfloat shadow2BlurRadius = 2.5f;

        var frame = Bounds;

        // Subframes
        var group = new CGRect(frame.GetMinX() + 3, frame.GetMinY() + 3, frame.Width - 6, frame.Height - 6);

        // UncheckedOval Drawing
        var uncheckedOvalPath = UIBezierPath.FromOval(new CGRect(group.GetMinX() + Math.Floor(group.Width * 0.00000 + 0.5), group.GetMinY() + Math.Floor(group.Height * 0.00000 + 0.5), Math.Floor(group.Width * 1.00000 + 0.5) - Math.Floor(group.Width * 0.00000 + 0.5), Math.Floor(group.Height * 1.00000 + 0.5) - Math.Floor(group.Height * 0.00000 + 0.5)));
        context.SaveState();
        context.SetShadow(shadow2Offset, shadow2BlurRadius, shadow2.CGColor);
        grayTranslucent.SetFill();
        uncheckedOvalPath.Fill();
        context.RestoreState();
        UIColor.White.SetStroke();
        uncheckedOvalPath.LineWidth = 1f;
        uncheckedOvalPath.Stroke();


        // Bezier Drawing
        var bezierPath = new UIBezierPath();
        bezierPath.MoveTo(new CGPoint(group.GetMinX() + 0.27083 * group.Width, group.GetMinY() + 0.54167 * group.Height));
        bezierPath.AddLineTo(new CGPoint(group.GetMinX() + 0.41667 * group.Width, group.GetMinY() + 0.68750 * group.Height));
        bezierPath.AddLineTo(new CGPoint(group.GetMinX() + 0.75000 * group.Width, group.GetMinY() + 0.35417 * group.Height));
        bezierPath.LineCapStyle = CGLineCap.Square;
        UIColor.White.SetStroke();
        bezierPath.LineWidth = 1.3f;
        bezierPath.Stroke();
    }

    private void DrawRectOpenCircle(CGRect rect)
    {
        var context = UIGraphics.GetCurrentContext();

        // Shadow Declarations
        var shadow = UIColor.Black;
        var shadowOffset = new CGSize(0.1, -0.1);
        nfloat shadowBlurRadius = 0.5f;
        var shadow2 = UIColor.Black;
        var shadow2Offset = new CGSize(0.1, -0.1);
        nfloat shadow2BlurRadius = 2.5f;

        var frame = Bounds;

        // Subframes
        var group = new CGRect(frame.GetMinX() + 3, frame.GetMinY() + 3, frame.Width - 6, frame.Height - 6);


        // EmptyOval Drawing
        var emptyOvalPath = UIBezierPath.FromOval(new CGRect(group.GetMinX() + Math.Floor(group.Width * 0.00000 + 0.5), group.GetMinY() + Math.Floor(group.Height * 0.00000 + 0.5), Math.Floor(group.Width * 1.00000 + 0.5) - Math.Floor(group.Width * 0.00000 + 0.5), Math.Floor(group.Height * 1.00000 + 0.5) - Math.Floor(group.Height * 0.00000 + 0.5)));
        context.SaveState();
        context.SetShadow(shadow2Offset, shadow2BlurRadius, shadow2.CGColor);
        context.RestoreState();
        context.SaveState();
        context.SetShadow(shadowOffset, shadowBlurRadius, shadow.CGColor);
        UIColor.White.SetStroke();
        emptyOvalPath.LineWidth = 1;
        emptyOvalPath.Stroke();
        context.RestoreState();
    }
}

public enum CheckMarkStyle
{
    OpenCircle,
    GrayedOut
}