c# - UIControllerView 不会从委托(delegate)函数更新
<p><p>我想通过委托(delegate)方法更新 <code>UIViewController</code> 中的 <code>UIView</code>。</p>
<p>有草图:
用户从 <code>UIViewController</code> 触发下载，下载由一个类管理，当 <code>UploadAsyncData</code> 完成时，下载方法将处理后的响应传递给另一个类。该类将接收到的数据写入本地数据库。</p>
<p>我想通知用户将 <code>UIViewController</code> 从进程进度中扔到哪里。</p>
<p>从现在开始我做了什么:</p>
<ul>
<li><p>在 <code>UIViewController</code> 我有一个 <code>UIView</code> 代表一个 <code>Overlay</code> 上面有一些消息。 <code>UIView</code> 也被设置为一个静态帮助类，以帮助从外部引用它。</p></li>
<li><p>当用户按下下载按钮时，<code>Overlay</code> 会显示并通知用户操作已被触发。</p></li>
<li><p>将操作传递给下载类时，<code>Overlay</code> 文本会更新为“您的下载正在进行中”</p></li>
<li><p>下载完成后，下载类中处理响应的方法将 <code>Overlay</code> 文本更新为“下载完成，正在处理接收到的数据...”</p></li >
<li><p>由于收到的数据是一个 C# 对象，我从该对象调用 SaveToDatabase 方法。</p></li>
<li><p>SaveToDatabase 方法使用进度指示器更新 <code>Overlay</code>。</p></li>
</ul>
<p>到目前为止，除了 <code>SaveToDatabase</code> 步骤之外，所有步骤都正确更新了 <code>Overlay</code> 消息。
调试时，我可以看到更新 <code>Overlay</code> 文本的方法在每一步都被调用，但 <code>UIView</code> 文本没有更新。</p>
<p>我不能使用 <code>InvokeOnMainThread</code> 因为 SaveToDatabase 不是 <code>UIViewController</code> 我不明白为什么所有步骤都正确更新 UIView 但最后一个没有.</p>
<p>这是所有这一步的一些提取代码。</p>
<p><strong>主要方法</strong></p>
<pre><code>public class Program:UIViewController
{
{...}
public override void ViewDidLoad()
{
base.ViewDidLoad();
AddOverlay();
}
public void AddOverlay()
{
var bounds = UIScreen.MainScreen.Bounds;
bounds.Size = new CGSize(bounds.Size.Width, bounds.Size.Height);
loadingOverlay = new LoadingOverlay(bounds);
loadingOverlay.Hidden = true;
View.Add(loadingOverlay);
System.Diagnostics.Debug.WriteLine(this.GetType().Name + loadingOverlay.GetHashCode());
Helpers.LoadingOverlay = loadingOverlay;
}
public void DisplayOverlay(string text)
{
if(loadingOverlay != null){
View.BringSubviewToFront(loadingOverlay);
System.Diagnostics.Debug.WriteLine(this.GetType().Name + loadingOverlay.GetHashCode());
loadingOverlay.Hidden = false;
loadingOverlay.SetLoadingLabel( text );
}
}
void Tablesource_OnRowSelected(object sender, eConversion5.DownloadTableSource.RowSelectedEventArgs e)
{
bool isReacheable = myParameters.IsReachable();
if (isReacheable) {
DisplayOverlay("Your download is about to start...");
Request request = new Request(url, myParameters);
request.CanBeSaved = false;
request.Action = "display";
httpCommunication.DoRequest(request);
}
}
}
</code></pre>
<p><strong>处理downloadAction的方法</strong></p>
<pre><code>public class HttpCommunication
{
{...}
public HttpCommunication(Parametrage parameters, HttpResponseAction responseAction)
{
client = new XSWebClient();
client.UploadDataCompleted += OnUploadDataCompleted;
}
public void DoRequest(Request JRequest)
{
{...}
SendRequest();
}
void SendRequest()
{
{...}
client.UploadDataAsync(Request.Uri, "POST", bytes);
{...}
}
void OnUploadDataCompleted(object sender, UploadDataCompletedEventArgs e)
{
Helpers.UpdateOverlayMessage("Processing recieved response...");
{...}
HandleResponse handler = new HandleResponse(myParameters, e.Result);
{...}
}
}
</code></pre>
<p><strong>处理服务器响应的类</strong></p>
<pre><code>public class HttpResponseAction
{
{...}
public void ExecuteAction(HandleResponse handled, Request request)
{
{...}
Helpers.UpdateOverlayMessage("Processing response...");
{...}
HandleTrainings(queryId, action, JsonConvert.DeserializeObject<List<TrainingContainer>>(json, Settings));
{...}
}
void HandleFormation(string queryId, string action, object nestedResult)
{
{...}
if (action == "display") {
result.SaveToDatabase();
{...}
}
{...}
}
}
</code></pre>
<p>最后一步，即不更新 UIView(之前的所有步骤都在正确更新它)</p>
<pre><code>public class TrainingContainer
{
{...}
public void SaveToDatabase()
{
if(SignList != null){
Helpers.UpdateOverlayMessage("Updating sign list in progress, may be take a while...");
int updated = 0;
int total = SignList.Count();
if(total > 0){
foreach (Training training in SignList) {
updated++;
float progress = (float) updated / total;
Helpers.UpdateProgressValue(progress); //From debbuging, i can see that this method is called, and Overlay object is the same throw all class calls from the starting point.
{...}
}
}
}
{...}
}
}
</code></pre>
<p><strong>助手类</strong></p>
<pre><code>public static class Helpers
{
public static LoadingOverlay LoadingOverlay;
{...}
public static void UpdateOverlayMessage(string message)
{
if(LoadingOverlay != null){
StackTrace stackTrace = new StackTrace();
System.Diagnostics.Debug.WriteLine(typeof(Helpers).Name + " (called from " + stackTrace.GetFrame(1).GetMethod().Name+ ")" + LoadingOverlay.GetHashCode());
LoadingOverlay.SetLoadingLabel(message);
}
}
public static void UpdateProgressValue(float progessValue)
{
if (LoadingOverlay != null) {
StackTrace stackTrace = new StackTrace();
System.Diagnostics.Debug.WriteLine(typeof(Helpers).Name + " (called from " + stackTrace.GetFrame(1).GetMethod().Name + ")" + LoadingOverlay.GetHashCode());
LoadingOverlay.UpdateProgress(progessValue);
}
}
}
</code></pre>
<p>编辑:从对 Helper 的调用中记录的一些跟踪记录。</p>
<pre><code>Helpers <UpdateOverlayMessage> :Transmitting request to the server...(called from Apply) -2037862263
Helpers <UpdateOverlayMessage> :Processing recieved response...(called from Apply) -2037862263
Helpers <UpdateOverlayMessage> :Processing response...(called from Apply) -2037862263
Helpers <UpdateOverlayMessage> :Updating sign list in progress, may be take a while...(called from Apply) -2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
Helpers <UpdateProgressValue> (called from Apply)-2037862263
</code></pre>
<p>更新 2:
忘记显示 Overlay 类</p>
<pre><code>public class LoadingOverlay : UIView {
// control declarations
UIActivityIndicatorView activitySpinner;
UILabel loadingLabel;
UIProgressView progressView;
public LoadingOverlay (CGRect frame) : base (frame)
{
// configurable bits
BackgroundColor = UIColor.Black;
Alpha = 0.55f;
AutoresizingMask = UIViewAutoresizing.All;
nfloat labelHeight = 22;
nfloat labelWidth = Frame.Width - 20;
// derive the center x and y
nfloat centerX = Frame.Width / 2;
nfloat centerY = Frame.Height / 2;
// create the activity spinner, center it horizontall and put it 5 points above center x
activitySpinner = new UIActivityIndicatorView(UIActivityIndicatorViewStyle.WhiteLarge);
activitySpinner.Frame = new CGRect (
centerX - (activitySpinner.Frame.Width / 2) ,
centerY - activitySpinner.Frame.Height - 20 ,
activitySpinner.Frame.Width,
activitySpinner.Frame.Height);
activitySpinner.AutoresizingMask = UIViewAutoresizing.All;
AddSubview (activitySpinner);
activitySpinner.StartAnimating ();
// create and configure the "Loading Data" label
loadingLabel = new UILabel(new CGRect (
centerX - (labelWidth / 2),
centerY + 20 ,
labelWidth ,
labelHeight
));
loadingLabel.BackgroundColor = UIColor.Clear;
loadingLabel.TextColor = UIColor.White;
loadingLabel.Text = "Wait a moment...";
loadingLabel.TextAlignment = UITextAlignment.Center;
loadingLabel.AutoresizingMask = UIViewAutoresizing.All;
AddSubview (loadingLabel);
progressView = new UIProgressView();
progressView.Progress = 0.0f;
var screenParts = Frame.Width / 3;
progressView.Frame = new CGRect(new CGPoint(screenParts,loadingLabel.Frame.Y + loadingLabel.Frame.Height + 20), new CGSize(screenParts,40));
progressView.Hidden = true;
AddSubview(progressView);
}
/// <summary>
/// Fades out the control and then removes it from the super view
/// </summary>
public void Hide ()
{
progressView.Progress = 0.0f;
InvokeOnMainThread(() => {
UIView.Animate(
0.5, // duration
() => { Alpha = 0; },
() => { RemoveFromSuperview(); }
);
});
}
public void SetLoadingLabel(String text)
{
InvokeOnMainThread(() => {
loadingLabel.Text = text;
});
}
public void UpdateProgress(float progressValue){
if(progressView.Hidden){
progressView.Hidden = false;
}
if(progressValue > 1){
progressValue = 1;
}
InvokeOnMainThread(() => {
progressView.SetProgress(progressValue, true);
});
}
}
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>确保在更新 UI 时它在主线程上运行。 InvokeOnMainThread 方法是在 NSObject 上定义的，所以让 Helper 类继承自 NSObject。所以 Helper 类可以改进如下:</p>
<pre><code> public sealed class Helpers:NSObject
{
public LoadingOverlay LoadingOverlay;
private static readonly Helpers instance = new Helpers();
private Helpers(){}
public static Helpers Instance
{
get
{
return instance;
}
}
public void UpdateOverlayMessage(string message)
{
InvokeOnMainThread ( () => {
if(LoadingOverlay != null){
StackTrace stackTrace = new StackTrace();
System.Diagnostics.Debug.WriteLine(typeof(Helpers).Name + " (called from " + stackTrace.GetFrame(1).GetMethod().Name+ ")" + LoadingOverlay.GetHashCode());
LoadingOverlay.SetLoadingLabel(message);
}
});
}
//So does the method "UpdateProgressValue".
}
</code></pre>
<p>在主方法中:</p>
<pre><code>Helpers.Instance.LoadingOverlay = loadingOverlay;
</code></pre>
<p>更新界面时:</p>
<pre><code>Helpers.Instance.UpdateOverlayMessage("...");
</code></pre></p>
<p style="font-size: 20px;">关于c# - UIControllerView 不会从委托(delegate)函数更新，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/43386614/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/43386614/
</a>
</p>
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