Xamarin.Forms

Question

我需要显示一个警报，消息的某些部分以斜体显示，而另一部分正常显示，如下所示：

var title = "Title";
var body = "This part in Italic. This part normal.";
Application.Current.MainPage.DisplayAlert(title, body, "OK");

其中表示的部分："This part in Italic." 为斜体，另一部分为普通文本。

可以吗？如果是，如何？

提前致谢！

Answer 1

您可以尝试使用自定义渲染器来实现（使用自定义视图和渲染器来处理弹出窗口）但是 it is not recommended by iOS

Alerts convey important information related to the state of your app or the device, and often request feedback. An alert consists of a title, an optional message, one or more buttons, and optional text fields for gathering input. Aside from these configurable elements, the visual appearance of an alert is static and can’t be customized.

This 可能对您有所帮助。

Answer 2

我最终创建了一个像这样的本机警报控制器：

void PromptRichTextPopup(string title, string richMessage, string normalMessage, Action onOkCallback, Action onCancel = null) {
            var vc = UIKit.UIApplication.SharedApplication.KeyWindow.RootViewController;
            // take top presented view controller
            while (vc.PresentedViewController != null) {
                vc = vc.PresentedViewController;
            }

            var alertvc = UIAlertController.Create(title, string.Empty, UIAlertControllerStyle.Alert);
            var leftAligned = new NSMutableParagraphStyle();
            leftAligned.Alignment = UITextAlignment.Left;

            var colorTitle = new NSAttributedString(str: title, font: UIFont.BoldSystemFontOfSize(18), foregroundColor: Xamarin.Forms.Color.FromHex("#61acad").ToUIColor());

            alertvc.SetValueForKey(colorTitle, new NSString("attributedTitle"));

            var margin = 5f;
            var height = 30f;
            var width = 256f;

            var container = new UIView(new CGRect(margin, margin, width, height * 4));

            var message = new NSMutableAttributedString(str: richMessage, font: UIFont.ItalicSystemFontOfSize(14), foregroundColor: UIColor.Black);
            message.Append(new NSMutableAttributedString(str: " " + normalMessage, font: UIFont.SystemFontOfSize(14), foregroundColor: UIColor.Black));
            var lblText = new UILabel(new CGRect(0, -(height / 2), width, height * 2)) { AttributedText = message };
            lblText.LineBreakMode = UILineBreakMode.WordWrap;
            lblText.Lines = 0;
            container.AddSubview(lblText);

            var cancel = new UIButton(new CGRect(0, height, width / 2, height * 2));
            cancel.SetTitle("NO", UIControlState.Normal);
            cancel.AddTarget((sender, e) => alertvc.DismissViewController(true, null), UIControlEvent.TouchUpInside);
            cancel.SetTitleColor(UIColor.Blue, UIControlState.Normal);
            if (onCancel != null) {
                cancel.AddTarget((sender, e) => {
                    onCancel();
                },
                UIControlEvent.TouchUpInside);
            }
            container.AddSubview(cancel);

            var ok = new UIButton(new CGRect(width / 2, height, width / 2, height * 2));
            ok.SetTitle("YES", UIControlState.Normal);
            Action okAction = async () => {
                ok.Enabled = false;
                await uiHelper.RunBlocking(() => {
                    onOkCallback();
                });
                alertvc.DismissViewController(true, null);
            };
            ok.SetTitleColor(UIColor.Blue, UIControlState.Normal);
            container.AddSubview(ok);
            ok.AddTarget((sender, e) => {
                okAction();
            }, UIControlEvent.TouchUpInside);

            var controller = new UIViewController();
            controller.View.AddSubview(container);
            alertvc.SetValueForKey(controller, new NSString("contentViewController"));
            vc.PresentViewController(alertvc, true, null);
        }

Xamarin.Forms - DisplayAlert with Italic 字体属性

Xamarin.Forms - DisplayAlert with Italic font attribute

popup

italic

xamarin