import UIKit

enum NetworkError: Error {
    case invalidServerResponse
    case unsupportedImage
}

func fetchPhoto(url: URL) async throws -> UIImage {
    let (data, response) = try await URLSession.shared.data(from: url)
    
    guard let httpResponse = response as? HTTPURLResponse,
          httpResponse.statusCode == 200 else {
              throw NetworkError.invalidServerResponse
    }
    
    guard let image = UIImage(data: data) else {
        throw NetworkError.unsupportedImage
    }
    
    return image
}

let photoURL = URL(string: "https://developer.apple.com/swift/images/swift-og.png")!

// using `async` here to test calling an `async/await` function since we cannot call it synchronously
// `async(priority:operation:)`: Runs the given nonthrowing operation asynchronously as part of a new top-level task on behalf of the current actor.
// Swift's new Concurrency Framework: https://developer.apple.com/documentation/swift/swift_standard_library/concurrency
async { 
    do {
        let image = try await fetchPhoto(url: photoURL)
        print(image)
    } catch {
        print(error)
    }
}


// <UIImage:0x600003a8c6c0 anonymous {1200, 1200} renderingMode=automatic>