ImageDownloader

Introduction

You can register the way remote images will be downloaded and populated in UIImageView by providing a class that implements this logic, which was added to Beagle in version 1.3.0.

With ImageDownloader being created in the frontend of your iOS application, Beagle will know which logic to use to download and configure the Image component of type ImagePath.Remote.

ImageDownloaderProtocol

The ImageDownloaderProtocol consists of only one method called fetchImage that will be used to request your remote images.

public protocol ImageDownloaderProtocol {
    @discardableResult
    func fetchImage(
        url: String,
        additionalData: HttpAdditionalData?,
        completion: @escaping (Result<Data, Request.Error>) -> Void
    ) -> RequestToken?
}

The fetchImage method takes 3 parameters:

• url: value of type String to which the image url will be passed through
• additionalData: HttpAdditionalData value, which can be used when there is a need to pass additional headers for a given request.
• completion: block that must be called at the end of the function execution passing the result of the request.

In addition, the function can return a RequestToken so that the request can be canceled internally by Beagle.

Default Implementation

In Beagle iOS, we have a class called ImageDownloaderDefault that performs the requests for images according to your network layer.

In its fetchImage method, this class calls RequestDispatcher with type .fetchImage and maps the result of that request according to the implementation of your network layer. You can see how to configure a network layer in here.

Replacing the default implementation

To replace the class responsible for making image requests on Beagle, follow the steps below:

Step 1: Implement ImageDownloaderProtocol

Implement the ImageDownloaderProtocol in the class you wish to use to make requests, in this case we created a class CustomImageDownloader that will be used as an example:

class CustomImageDownloader: ImageDownloaderProtocol {
    func fetchImage(
        url: String,
        additionalData: RemoteScreenAdditionalData?,
        completion: @escaping (Result<Data, Request.Error>) -> Void
    ) -> RequestToken? {
        let newUrl: URL = URL(string: url)
        //Implementation of image request
    }
    //Additional implementation...
}

Step 2: Assign the dependencies

In AppDelegate or in Beagle environment settings class, assign the instance of CustomImageDownloader to the imageDownloader attribute present in BeagleDependencies:

let dependencies = BeagleDependencies()
dependencies.imageDownloader = CustomImageDownloader()
BeagleConfigurator.setup(dependencies: dependencies)

Done! Beagle will now use your class with all the necessary modifications and settings to download your remote images.

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