AuthManager.shared.login(email: "email", password: "pass") { result in
    switch result {
    case .success(let user):
        print(user.providerID)
    case .failure(let error):
        print(error.localizedDescription)
    }
}

AuthManager.shared.register(email: "email", password: "pass", confirmPassword: "pass") { result in
    switch result {
    case .success(let user):
        print(user.providerID)
    case .failure(let error):
        print(error.localizedDescription)
    }
}

AuthManager.shared.resetPassword(email: "email") { result in
    switch result {
    case .success(_):
        print("success")
    case .failure(let error):
        print(error.localizedDescription)
    }
}

AuthManager.shared.logout()

<- Here you must specify the ID of the user you want to download from. StorageManager.shared.upload(userPhoto: userImage, userId: id) { (result) in switch result { case .success(let url): print(url.absoluteString) case .failure(let error): print(error.localizedDescription) } } ">

let userImage = UIImage() // <- Here should be the image you want to upload.
let id = "USER_ID" // <- Here you must specify the ID of the user you want to download from.

StorageManager.shared.upload(userPhoto: userImage, userId: id) { (result) in
    switch result {
    case .success(let url):
        print(url.absoluteString)
    case .failure(let error):
        print(error.localizedDescription)
    }
}

guard let url = URL(string: "URL_STRING_TO_IMAGE") else { return }

StorageManager.shared.downloadImage(url: url) { (result) in
    switch result {
    case .success(let image):
        print("success")
    case .failure(let error):
        print(error.localizedDescription)
    }
    
}

let user = Auth.auth().currentUser! // <- There must be a class User object here.
 // For example when you get a user in the response after registering Firebase.

FirestoreManager.shared.getUserData(user: user) { (result) in
    switch result {
    case .success(let firestoreUserModel):
        print(firestoreUserModel.firstName)
    case .failure(let error):
        print(error.localizedDescription)
    }
}

let user = FirestoreUserModel() // <- There must be a class FirestoreUserModel object here.
// For example when you get a user in the response after registering Firebase.

FirestoreManager.shared.saveProfile(user: user, userImage: nil) { (result) in
    switch result {
    case .success(let firestoreUserModel):
        print(firestoreUserModel.firstName)
    case .failure(let error):
        print(error.localizedDescription)
    }
}

func exampleRequest(completion: @escaping (Result?, Error>) -> Void) {
    guard let url = URL(string: "API_URL_STRING") else { return }
    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    
    // If the request contains headers.
    let headers = ["EXAMPLE_API_HEADER_KEY" : "EXAMPLE_API_HEADER_VALUE",
                   "EXAMPLE_API_HEADER_KEY" : "EXAMPLE_API_HEADER_VALUE"]
    request.allHTTPHeaderFields = headers
    
    // If the request contains parameters.
    let params = ["EXAMPLE_API_PARAMS_KEY" : "EXAMPLE_API_PARAMS_VALUE",
                  "EXAMPLE_API_PARAMS_KEY" : "EXAMPLE_API_PARAMS_VALUE"]
    let data = try? JSONSerialization.data(withJSONObject: params, options: [])
    request.httpBody = data
    
    AF.request(request).responseJSON { (response) in
        switch response.result {
        case .success(_):
            completion(.success(response.data))
        case .failure(let error):
            completion(.failure(error))
        }
    }
}

NetworkManager.shared.exampleRequest { result in
    switch result {
    case .success(let data):
        print("success")
    case .failure(let error):
        print(error.localizedDescription)
    }
}

guard let data = data else { return }
if let object = NetworkHelpers.shared.parseExampleModel(data) {
    print(object.name)
}

func exampleRequest(completion: @escaping (ExampleModel?) -> Void) {
    let urlString = "API_URL_STRING"
    dataFetcher.fetchJSONData(urlString: urlString, headers: nil, response: completion)
}

struct ExampleModel: Codable {
    let main: Main
    let name: String
}

struct Main: Codable {
    let firstValue: Double
    let secondValue: Double
}

var dataFetcherManager = DataFetcherManager()

dataFetcherManager.exampleRequest { exampleModel in
    guard let exampleModel = exampleModel else { return }
    print(exampleModel.name)
}