Question

对于以下代码，我调用async void方法。

<Project ToolsVersion="4.0" DefaultTargets="RunUnitTests" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> 

  <!-- Falls Eigenschaften nicht gesetzt -> Release & Any CPU als default-->
  <PropertyGroup>
    <!-- ... -->
  </PropertyGroup>

  <ItemGroup>
    <!-- ... -->
  </ItemGroup>

  <!-- All the stuff go into my main folder -->
  <Target Name="Init" DependsOnTargets="Clean">
    <MakeDir Directories="@(BuildArtifacts)" />
  </Target>

  <!-- delete my main folder -->
  <Target Name="Clean">
    <RemoveDir Directories="@(BuildArtifactsDir)" />
  </Target>

  <!-- delete NUnit-Files -->
  <Target Name="CleanAfter">
    <RemoveDir Directories="@(NunitDir)" />
  </Target>

  <Target Name="Compile" DependsOnTargets="Init">
    <MSBuild Projects="@(SolutionFile)" 
    Targets="Rebuild" 
    Properties="OutDir=%(BuildArtifactsDir.FullPath);
    Configuration=$(Configuration);
    Platform=$(BuildPlatform)" />
  </Target>

  <Target Name="RunUnitTests" DependsOnTargets="Compile">
         <Exec Command='"@(NUnitConsole)" "@(UnitTestsDLL)" --result=console-test.xml --work=BuildArtifacts' />
         <CallTarget Targets="CleanAfter" />
  </Target>

</Project>

以下代码为public void LoadSystemDetails(int clientId) { DataSystem.Name = "Salesforce System"; DataSystem.Description = ""; GetAllFields(clientId); }方法

GetAllFields

我打电话给public async void GetAllFields(int clientId) { this.DataSystem.SystemTables = new List<DataSystemTable>(); using (var forceClient = await ConnectToSalesforceByOAuth(clientId)) { var SalesForceTable = new DataSystemTable { TableName = "Contact" }; DataSystem.SystemTables.Add(SalesForceTable); var contact = forceClient.DescribeAsync<SalesforceObject>("Contact"); var tableFields = new List<DataSystemField>(); foreach (var con in contact.Result.Fields) { tableFields.Add(new DataSystemField { ColumnName = con.Name, }); } SalesForceTable.EissSyncSystemFields = tableFields; }如下。

callbackScript

此处callbackScript.AppendLine(string.Format("var destinationSystem ={0};", JsonConvert.SerializeObject(this.DestinationSystem, Formatting.Indented)));正在调用DestinationSystem。与LoadSystemDetails

一样

DestinationSystem.LoadSystemDetails(clientId)行在using (var forceClient = await ConnectToSalesforceByOAuth(clientId))执行时执行。所以callbackScript没有任何价值。但它有SystemTables和Name。

所以我需要等Description完成LoadSystemDetails。

我是怎么做的。请帮帮我。感谢。

Answer 1

如果您需要LoadSystemDetails等待GetAllFields，则此处存在以下两个问题：

您正在从同步上下文中调用异步方法
GetAllFields是异步无效，这意味着火与忘。你永远无法等待它完成。

解决方案：首先，如果您需要等待结果或结束，切勿使用async void。请使用async Task代替其次，将LoadSystemDetails转换为异步方法，然后等待GetAllFields（应返回Task），或使用GetAllFields(clientId).Wait()

有关async / await的更多信息，请查看本文：https://msdn.microsoft.com/en-us/magazine/jj991977.aspx

Answer 2

正如@netchkin已经说过：永远不要使用- (UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{ static NSString *identifier = @"Cell"; StudentTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier forIndexPath:indexPath]; if (cell == nil) { cell = [[StudentTableViewCell alloc] init]; } if (_btnCancel.hidden == NO) { TeacherInfo *courseStudent = studentQuitArray[indexPath.row]; if ([studentDetail containsObject:courseStudent]) { cell.accessoryType = UITableViewCellAccessoryCheckmark; else { cell.accessoryType = UITableViewCellAccessoryNone; } } else { cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; } return cell; }。使用-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{ UITableViewCell* cellCheck = [tableView cellForRowAtIndexPath:indexPath]; NSMutableDictionary *dict = [[NSMutableDictionary alloc] init]; if (_btnCancel.hidden == NO) { if (cellCheck.accessoryType == UITableViewCellAccessoryNone) { cellCheck.accessoryType = UITableViewCellAccessoryCheckmark; TeacherInfo *courseStudent = studentQuitArray[indexPath.row]; [dict setObject:courseStudent.id_user forKey:@"student_id"]; [studentDetail addObject:dict]; } else { cellCheck.accessoryType = UITableViewCellAccessoryNone; [studentDetail removeObject: studentQuitArray[indexPath.row]]; } } }。您不必自己返回async void，仍然可以使用async Task

如何在异步方法中等待等待完成所有执行？

2 个答案: