Вот еще одно обновление, основанное на материалах, сделанных Мигелем, Алесом, Дэнмистером и Патриком.
С момента выхода iOS 11, в частности версии 11.1.2 (я впервые заметил это на этом), оригиналРешение, опубликованное мной (Алеся), стало ненадежным, начало зависать случайным образом.Этот использует явно вызванный NSRunLoop.Current.RunUntil ().
Так что я обновил свой исходный класс, чтобы фактически предлагать методы синхронизации и асинхронности, и сделал несколько других изменений, чтобы сразу после любой кнопки освободить памятьпри нажатии также добавляется код, выравнивающий текст по левому краю, если обнаружены разрывы строк Windows CRLF.
Пространства имен:
using System;
using CoreGraphics;
using UIKit;
using Foundation;
using System.Collections.Generic;
using System.Threading.Tasks;
Код:
public enum MessageBoxResult
{
None = 0,
OK,
Cancel,
Yes,
No
}
public enum MessageBoxButton
{
OK = 0,
OKCancel,
YesNo,
YesNoCancel
}
public static class MessageBox
{
/* This class emulates Windows style modal boxes. Unfortunately, the original code doesn't work reliably since cca iOS 11.1.2 so
* you have to use the asynchronous methods provided here.
*
* The code was a bit restructured utilising class MessageBoxNonstatic to make sure that on repeated use, it doesn't allocate momere memory.
* Note that event handlers are explicitly removed and at the end I explicitly call garbage collector.
*
* The code is a bit verbose to make it easier to understand and open it to tweaks.
*
*/
// Synchronous methods - don't work well since iOS 11.1.2, often freeze because something has changed in the event loop and
// NSRunLoop.Current.RunUntil() is not reliable to use anymore
public static MessageBoxResult Show(string messageBoxText, string caption, MessageBoxButton buttonType)
{
MessageBoxNonstatic box = new MessageBoxNonstatic();
return box.Show(messageBoxText, caption, buttonType);
}
public static MessageBoxResult Show(string messageBoxText)
{
return Show(messageBoxText, "", MessageBoxButton.OK);
}
public static MessageBoxResult Show(string messageBoxText, string caption)
{
return Show(messageBoxText, caption, MessageBoxButton.OK);
}
// Asynchronous methods - use with await keyword. Restructure the calling code tho accomodate async calling patterns
// See https://docs.microsoft.com/en-us/dotnet/csharp/async
/*
async void DecideOnQuestion()
{
if (await MessageBox.ShowAsync("Proceed?", "DECIDE!", MessageBoxButton.YesNo) == MessageBoxResult.Yes)
{
// Do something
}
}
*/
public static Task<MessageBoxResult> ShowAsync(string messageBoxText, string caption, MessageBoxButton buttonType)
{
MessageBoxNonstatic box = new MessageBoxNonstatic();
return box.ShowAsync(messageBoxText, caption, buttonType);
}
public static Task<MessageBoxResult> ShowAsync(string messageBoxText)
{
return ShowAsync(messageBoxText, "", MessageBoxButton.OK);
}
public static Task<MessageBoxResult> ShowAsync(string messageBoxText, string caption)
{
return ShowAsync(messageBoxText, caption, MessageBoxButton.OK);
}
}
public class MessageBoxNonstatic
{
private bool IsDisplayed = false;
private int buttonClicked = -1;
private UIAlertView alert = null;
private string messageBoxText = "";
private string caption = "";
private MessageBoxButton button = MessageBoxButton.OK;
public bool IsAsync = false;
TaskCompletionSource<MessageBoxResult> tsc = null;
public MessageBoxNonstatic()
{
// Do nothing
}
public MessageBoxResult Show(string sMessageBoxText, string sCaption, MessageBoxButton eButtonType)
{
messageBoxText = sMessageBoxText;
caption = sCaption;
button = eButtonType;
IsAsync = false;
ShowAlertBox();
WaitInLoopWhileDisplayed();
return GetResult();
}
public Task<MessageBoxResult> ShowAsync(string sMessageBoxText, string sCaption, MessageBoxButton eButtonType)
{
messageBoxText = sMessageBoxText;
caption = sCaption;
button = eButtonType;
IsAsync = true;
tsc = new TaskCompletionSource<MessageBoxResult>();
ShowAlertBox();
return tsc.Task;
}
private void ShowAlertBox()
{
IsDisplayed = false;
buttonClicked = -1;
alert = null;
string cancelButton = "Cancel";
string[] otherButtons = null;
switch (button)
{
case MessageBoxButton.OK:
cancelButton = "";
otherButtons = new string[1];
otherButtons[0] = "OK";
break;
case MessageBoxButton.OKCancel:
otherButtons = new string[1];
otherButtons[0] = "OK";
break;
case MessageBoxButton.YesNo:
cancelButton = "";
otherButtons = new string[2];
otherButtons[0] = "Yes";
otherButtons[1] = "No";
break;
case MessageBoxButton.YesNoCancel:
otherButtons = new string[2];
otherButtons[0] = "Yes";
otherButtons[1] = "No";
break;
}
IUIAlertViewDelegate d = null;
if (cancelButton.Length > 0)
alert = new UIAlertView(caption, messageBoxText, d, cancelButton, otherButtons);
else
alert = new UIAlertView(caption, messageBoxText, d, null, otherButtons);
if (messageBoxText.Contains("\r\n"))
{
foreach (UIView v in alert.Subviews)
{
try
{
UILabel l = (UILabel)v;
if (l.Text == messageBoxText)
{
l.TextAlignment = UITextAlignment.Left;
}
}
catch
{
// Do nothing
}
}
}
alert.BackgroundColor = UIColor.FromWhiteAlpha(0f, 0.8f);
alert.Canceled += Canceled_Click;
alert.Clicked += Clicked_Click;
alert.Dismissed += Dismissed_Click;
alert.Show();
IsDisplayed = true;
}
// ======================================================================= Private methods ==========================================================================
private void WaitInLoopWhileDisplayed()
{
while (IsDisplayed)
{
NSRunLoop.Current.RunUntil(NSDate.FromTimeIntervalSinceNow(0.2));
}
}
private void Canceled_Click(object sender, EventArgs e)
{
buttonClicked = 0;
IsDisplayed = false;
DisposeAlert();
}
private void Clicked_Click(object sender, UIButtonEventArgs e)
{
buttonClicked = (int)e.ButtonIndex;
IsDisplayed = false;
DisposeAlert();
}
private void Dismissed_Click(object sender, UIButtonEventArgs e)
{
if (IsDisplayed)
{
buttonClicked = (int)e.ButtonIndex;
IsDisplayed = false;
DisposeAlert();
}
}
private void DisposeAlert()
{
alert.Canceled -= Canceled_Click;
alert.Clicked -= Clicked_Click;
alert.Dismissed -= Dismissed_Click;
alert.Dispose();
alert = null;
GC.Collect();
if (IsAsync)
GetResult();
}
private MessageBoxResult GetResult()
{
MessageBoxResult res = MessageBoxResult.Cancel;
switch (button)
{
case MessageBoxButton.OK:
res = MessageBoxResult.OK;
break;
case MessageBoxButton.OKCancel:
if (buttonClicked == 1)
res = MessageBoxResult.OK;
break;
case MessageBoxButton.YesNo:
if (buttonClicked == 0)
res = MessageBoxResult.Yes;
else
res = MessageBoxResult.No;
break;
case MessageBoxButton.YesNoCancel:
if (buttonClicked == 1)
res = MessageBoxResult.Yes;
else if (buttonClicked == 2)
res = MessageBoxResult.No;
break;
}
if (IsAsync)
tsc.TrySetResult(res);
return res;
}
}