Gravity is a SwiftUI library for remote data fetching. It uses SWR technonology to fetch data from the server.

The name “SWR” is derived from stale-while-revalidate, a cache invalidation strategy popularized by HTTP RFC 5861. Gravity first returns the data from cache (stale), then sends the fetch request (revalidate), and finally comes with the up-to-date data again.

With Gravity, components will get a stream of data updates constantly and automatically. Thus, the UI will be always fast and reactive.

The Swift Package Manager is a tool for automating the distribution of Swift code and is integrated into the swift compiler.

It is the recommended way to install Gravity.

Once you have your Swift package set up, adding Gravity as a dependency is as easy as adding it to the dependencies value of your Package.swift.

dependencies: [
    .package(url: "https://github.com/pr1mer-tech/Gravity.git", .upToNextMajor(from: "0.1.0"))
]

You can then import and use Gravity:

import SwiftUI
import Gravity

struct LandmarkList: View {
    @SWR<URL, Landmark>(url: "https://example.org/api/endpoint") var api
    var body: some View {
        if let landmarks = api.data {
            List(landmarks, id: \.id) { landmark in
                LandmarkRow(landmark: landmark)
            }
        }
    }
}

In this example, the property wrapper @SWR accepts a url and a model.

The url is the URL of the API. And the model is a Codable object.

api will be a StateResponse object that has three children: data that will contain the decoded data, error in case there is an error and awaiting when the app is loading.