Xamarin.iOS 未在警报中正确显示按钮

Question

我没有在 Alert.Is 上获得 OK 按钮这不是显示 OK 按钮警报的代码？

我需要改变什么？

    public void Alert (List<string> listToAlert, string heading)
            {
                    StringBuilder stringBuilder = new StringBuilder ();
                    for (int i = 0; i < listToAlert.Count; i++) {
                            stringBuilder.Append (listToAlert [i]);
                            stringBuilder.Append ("\r\n");
                    }
                    UIButton okayButton = new UIButton();
                    var okAlertController = UIAlertController.Create (heading, stringBuilder.ToString (), UIAlertControllerStyle.Alert);

                    okayButton.TouchUpInside += (sender, e) => {    
                            //Add Action
                            okAlertController.AddAction (UIAlertAction.Create ("Cancel", UIAlertActionStyle.Cancel, null));
                    };
                    _rootVC.PresentViewController (okAlertController, true, null);
            }

Answer 1

您正在添加操作，直到用户单击确定按钮，您应该在创建 UI 警报控制器后添加它

var okAlertController = UIAlertController.Create ("Title", "The      message", UIAlertControllerStyle.Alert);

    //Ads Action
    okAlertController.AddAction (UIAlertAction.Create ("OK", UIAlertActionStyle.Default, null));

    // Present Alert
    PresentViewController (okAlertController, true, null);

查看文档以查看更多示例https://docs.microsoft.com/en-us/xamarin/ios/user-interface/controls/alerts

Answer 2

这是一个可行的解决方案 - @Ricardo Romo 的上述解决方案无法编译。问题很可能是围绕 class 包含的类型的假设。 PresentViewController 假定呼叫 class 是 ViewController。在我和许多情况下，以及我的情况下，这并不总是正确的。我是从 appdelegate 打电话来的。

public class AlertViewController
    {
            #region Static Methods
            public static UIAlertController PresentOKAlert (string title, string description, UIViewController controller)
            {
                    // No, inform the user that they must create a home first
                    UIAlertController alert = UIAlertController.Create (title, description, UIAlertControllerStyle.Alert);

                    // Configure the alert
                    alert.AddAction (UIAlertAction.Create ("OK", UIAlertActionStyle.Default, (action) => { }));

                    // Display the alert
                    controller.PresentViewController (alert, true, null);

                    // Return created controller
                    return alert;
            }
            public static UIAlertController PresentOKCancelAlert (string title, string description, UIViewController controller, AlertOKCancelDelegate action)
            {
                    // No, inform the user that they must create a home first
                    UIAlertController alert = UIAlertController.Create (title, description, UIAlertControllerStyle.Alert);

                    // Add cancel button
                    alert.AddAction (UIAlertAction.Create ("Cancel", UIAlertActionStyle.Cancel, (actionCancel) => {
                            // Any action?
                            if (action != null) {
                                    action (false);
                            }
                    }));

                    // Add ok button
                    alert.AddAction (UIAlertAction.Create ("OK", UIAlertActionStyle.Default, (actionOK) => {
                            // Any action?
                            if (action != null) {
                                    action (true);
                            }
                    }));

                    // Display the alert
                    controller.PresentViewController (alert, true, null);

                    // Return created controller
                    return alert;
            }
            public static UIAlertController PresentTextInputAlert (string title, string description, string placeholder, string text, UIViewController controller, AlertTextInputDelegate action)
            {
                    // No, inform the user that they must create a home first
                    UIAlertController alert = UIAlertController.Create (title, description, UIAlertControllerStyle.Alert);
                    UITextField field = null;

                    // Add and configure text field
                    alert.AddTextField ((textField) => {
                            // Save the field
                            field = textField;

                            // Initialize field
                            field.Placeholder = placeholder;
                            field.Text = text;
                            field.AutocorrectionType = UITextAutocorrectionType.No;
                            field.KeyboardType = UIKeyboardType.Default;
                            field.ReturnKeyType = UIReturnKeyType.Done;
                            field.ClearButtonMode = UITextFieldViewMode.WhileEditing;

                    });

                    // Add cancel button
                    alert.AddAction (UIAlertAction.Create ("Cancel", UIAlertActionStyle.Cancel, (actionCancel) => {
                            // Any action?
                            if (action != null) {
                                    action (false, "");
                            }
                    }));

                    // Add ok button
                    alert.AddAction (UIAlertAction.Create ("OK", UIAlertActionStyle.Default, (actionOK) => {
                            // Any action?
                            if (action != null && field != null) {
                                    action (true, field.Text);
                            }
                    }));

                    // Display the alert
                    controller.PresentViewController (alert, true, null);

                    // Return created controller
                    return alert;
            }
            public static void Alert (List<string> listToAlert, string heading, UIViewController controller)
            {
                    StringBuilder stringBuilder = new StringBuilder ();
                    for (int i = 0; i < listToAlert.Count; i++) {
                            stringBuilder.Append (listToAlert [i]);
                            stringBuilder.Append ("\r\n");
                    }
                    AlertViewController.PresentOKAlert (heading, stringBuilder.ToString (), controller);
            }
            #endregion
            #region Delegates
            public delegate void AlertOKCancelDelegate (bool OK);
            public delegate void AlertTextInputDelegate (bool OK, string text);
            #endregion
    }

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