FetchStrategy typedef

FetchStrategy = Future<FetchInstructions> Function(Uri uri, FetchFailure? failure)

This function is called to get FetchInstructions to fetch an image.

The instructions are executed as soon as possible after the returned Future resolves. If a delay in necessary between retries, use a delayed Future, such as Future.delayed. This is useful for implementing back-off strategies and for recovering from lack of connectivity.

uri is the last requested image URI. A FetchStrategy may choose to use a different URI (see FetchInstructions.uri).

If failure is null, then this is the first attempt to fetch the image.

If the failure is not null, it contains the information about the previous attempt to fetch the image. A FetchStrategy may attempt to recover from the failure by returning FetchInstructions that instruct NetworkImageWithRetry to try again.

See NetworkImageWithRetry.defaultFetchStrategy for an example.

Implementation

typedef FetchStrategy = Future<FetchInstructions> Function(
    Uri uri, FetchFailure? failure);