IAsyncActionWithProgress<TProgress> IAsyncActionWithProgress<TProgress> IAsyncActionWithProgress<TProgress> IAsyncActionWithProgress<TProgress> IAsyncActionWithProgress<TProgress> Interface

Definition

Represents an asynchronous action that can report progress updates to callers. This is the return type for all Windows Runtime asynchronous methods that don't have a result object, but do report progress to callback listeners.

public : interface IAsyncActionWithProgress<TProgress> : IAsyncInfo
struct winrt::Windows::Foundation::IAsyncActionWithProgress<TProgress> : IAsyncInfo
public interface IAsyncActionWithProgress<TProgress> : IAsyncInfo
Public Interface IAsyncActionWithProgress<TProgress> Implements IAsyncInfo
// You can't instantiate an interface directly in JavaScript. You can use objects that implement the interface, however.
Inheritance
IAsyncActionWithProgress<TProgress>IAsyncActionWithProgress<TProgress>IAsyncActionWithProgress<TProgress>IAsyncActionWithProgress<TProgress>IAsyncActionWithProgress<TProgress>
Attributes
Windows 10 requirements
Device family
Windows 10 (introduced v10.0.10240.0)
API contract
Windows.Foundation.FoundationContract (introduced v1)

Remarks

IAsyncActionWithProgress; is the return type for all Windows Runtime asynchronous methods that don't communicate a result object, but do enable an app to check the progress of the action. There aren't nearly as many of these as there are methods that use IAsyncAction. IAsyncAction APIs don't report progress and don't have a result.

When you use methods that return IAsyncActionWithProgress; in your app code, you usually don't access the IAsyncAction return value directly. That's because you almost always use the language-specific awaitable syntax. In this case, the apparent return value of the method is void. For more info, see Asynchronous programming, or one of the language-specific guides to Windows Runtime asynchronous programming (Call asynchronous APIs in C# or Visual Basic, C++, JavaScript).

It's not common to use IAsyncActionWithProgress; directly even if you don't use a language-specific awaitable syntax. Each of the languages has extension points that are generally easier to use than the Windows Runtime interface. JavaScript has WinJS.Promise, and the then/done with onProgress syntax. .NET has the AsTask extension methods, and once the IAsyncActionWithProgress; is converted to a Task, it's easier to cancel, get notification on completion, use IProgress<T>, and so on. For C++/CX, you can wrap the calls using the Concurrency runtime (and use create_task). In other words, IAsyncActionWithProgress; can be considered runtime-level infrastructure, which each of the languages use as a framework to support awaitable syntax or asynchronous programming models in their own way.

Specifically, if you want to handle progress in .NET code, use the AsTask signature that in an extension usage has a single IProgress reference parameter. (In this usage, the progress unit is already constrained and matches the IAsyncActionWithProgress method you're using.) Provide an object that implements IProgress, and your Report method implementation is invoked each time the Windows Runtime method reports a progress notification.

To monitor the progress of the action (if not using the language-specific techniques described above), set the Progress property, providing it the name of a method that implements the AsyncActionProgressHandler; delegate.

Interface inheritance

IAsyncActionWithProgress; inherits IAsyncInfo.Types that implement IAsyncActionWithProgress; also implement the interface members of IAsyncInfo:

Notes to implementers

As with calling the existing methods, there are language-specific ways to define asynchronous methods that don't use IAsyncActionWithProgress; directly. If writing code using .NET, your method can return a Task. For C++/CX, you can use the Concurrency runtime. However, if you're defining a component, you can use Task/task internally but you must return one of the Windows Runtime interfaces for your public methods. The language-specific asynchronous support types (and many other language-specific types you might conventionally use in code) can't be used for the public surface area of a Windows Runtime component.

Properties

Completed Completed Completed Completed Completed

Gets or sets the method that handles the action completed notification.

ErrorCode ErrorCode ErrorCode ErrorCode ErrorCode

Gets a string that describes an error condition of the asynchronous operation.

(Inherited from IAsyncInfo)
Id Id Id Id Id

Gets the handle of the asynchronous operation.

(Inherited from IAsyncInfo)
Progress Progress Progress Progress Progress

Gets or sets the callback method that receives progress notification.

Status Status Status Status Status

Gets a value that indicates the status of the asynchronous operation.

(Inherited from IAsyncInfo)

Methods

Cancel Cancel Cancel Cancel Cancel

Cancels the asynchronous operation.

(Inherited from IAsyncInfo)
Close Close Close Close Close

Closes the asynchronous operation.

(Inherited from IAsyncInfo)
GetResults() GetResults() GetResults() GetResults() GetResults()

Returns the results of the action.

See Also