I am trying a simple exercise to demonstrate using async/await in Swift and, best that I can isolate, the app crashes when executing the Task statement. I have tried catching the exception on-throw and on-catch and the call stack does not provide any additional insight into the issue. The error is on Thread 1:
Thread 1: EXC_BAD_ACCESS (code=1, address=0x0)
My theory is that the COMMAND LINE template does not support Task in this simple form.
//
// main.swift
//
import Foundation
struct User {
var username: String
var movies = [Movie]()
}
struct Movie {
var title: String
var rating: Double?
}
class ManagerUsingAsync {
func getUsers() async throws -> [User] {
let allIsGood = true // Bool.random()
if allIsGood {
let users = ["mary", "casey", "theo", "dick"].map { User(username: $0) }
return users
} else {
throw URLError(.cannotConnectToHost)
}
}
func getUsersMovies(username: String) async throws -> [Movie] {
let allIsGood = true // Bool.random()
if allIsGood {
let movies = ["breaking away", "diner", "the great escape"].map { Movie(title: $0) }
return movies
} else {
throw URLError(.cannotCreateFile)
}
}
func getMovieRating(title: String) async -> Double? {
let allIsGood = true // Bool.random()
if allIsGood {
return Double.random(in: 1...10)
}
return nil
}
}
func testAsync() async -> [User] {
var _users = [User]()
let manager = ManagerUsingAsync()
do {
_users = try await manager.getUsers()
for var user in _users {
user.movies = try await manager.getUsersMovies(username: user.username)
for var movie in user.movies {
movie.rating = await manager.getMovieRating(title: movie.title)
}
}
} catch (let error) {
print(error.localizedDescription)
}
return _users
}
print("TEST ASYNC/AWAIT...")
Task {
let users = await testAsync()
for user in users {
print( "Username: \(user.username) Movies: \(user.movies)" )
}
}
Apparently this is somehow related to how my corporate MacBook is locked-down. I cannot figure this out in deeper detail, but the same code works fine (as did for #RobNapier as shared in the comments) on my personal MacBook.
Not sure if this Q should be withdrawn, but there is something to be learned about corporate MDM impact on developers (not the first time). FWIW -- My corp MacBook is managed by JAMF.
It is my first time working with smart contracts and my goal is to create a mobile app which can interact with it by calling methods to save or retrieve data. For this reason I have created a very simple contract using Remix and I have also deployed on Rinkeby testnet.
contract Storage {
uint256 number;
function store(uint256 num) public {
number = num;
}
function retrieve() public view returns (uint256){
return number;
}
}
Then I built a SwiftUI app, which has one button. When I press this button, I want to call the store method and save some int number. For example number 9. Therefore I have created a function called write which looks as following:
let myInt = 9
func write() {
let web3 = Web3.InfuraRinkebyWeb3(accessToken: "https://rinkeby.infura.io/v3/a146daf63d93490995823f0910f50118")
let walletAddress = EthereumAddress("0xc65943Fae5a554e7DCF916F8828a73E5f7b1bDCd")! // Your wallet address
let contractMethod = "store" // Contract method you want to write
let contractABI = contractABIString // Contract ABI
let contractAddress = EthereumAddress("0x2826C42354FE5B816c7E21AD9e3B395Ced512C0C")!
let abiVersion = 2 // Contract ABI version
let parameters = [myInt] as [AnyObject]
let extraData: Data = Data() // Extra data for contract method
let contract = web3.contract(contractABI, at: contractAddress, abiVersion: abiVersion)!
var options = TransactionOptions.defaultOptions
options.from = walletAddress
options.gasPrice = .automatic
options.gasLimit = .automatic
do {
contract.write(
contractMethod,
parameters: parameters,
extraData: extraData,
transactionOptions: options)
} catch {
print("error:", error)
}
Unfortunately, when I run this code, nothing is happening. I don't get any error but when I refresh the contract I see that number 9 is not passed.
I am using web3swift library, https://github.com/skywinder/web3swift/tree/master#send-erc-20-token. According to the documentation, it should be fine, but it is not working, therefore I would really appreciate some assistant to make it work or some example projects where I can take a look, because I also couldn't find anything.
I found some other project using JS and I see the people there use their private keys, maybe I also need it, but since it is not shown in the documentation, I was not sure how to use it.
The smart contract interaction requires a few initialisations steps:
Your wallet
KeyStoreManager
web3
Let's assume you already got a Metamask wallet.
Separately you need to have a separate file containing the ABI of the smartContract you want to interact with.
It is an array and having it in a Swift.String is easier.(I won't show you this step)
struct Wallet {
let address: String
let data: Data
let name: String
let isHD: Bool
}
class SmartContractInteraction {
var wallet: Wallet!
var keystoreManager: KeystoreManager!
var web3: web3!
init() {
wallet = initializeWallet()
keystoreManager = getKeyStoreManager()
web3 = initializeweb3()
}
private func initializeWallet() -> Wallet? {
let password = "PasswordMetamask"
let key = "AccountPrivateKey"
let formattedKey = key.trimmingCharacters(in: .whitespacesAndNewlines)
let dataKey = Data.fromHex(formattedKey)!
let name = "Account 1"
do {
let keystore = try EthereumKeystoreV3(privateKey: dataKey, password: password)!
let keyData = try JSONEncoder().encode(keystore.keystoreParams)
let address = keystore.addresses!.first!.address
return Wallet(address: address, data: keyData, name: name, isHD: false)
} catch {
print("wallet init failed: \(error)")
return nil
}
}
private func getKeyStoreManager() -> KeystoreManager {
let data = wallet.data
let keystoreManager: KeystoreManager
if wallet.isHD {
let keystore = BIP32Keystore(data)!
keystoreManager = KeystoreManager([keystore])
} else {
let keystore = EthereumKeystoreV3(data)!
keystoreManager = KeystoreManager([keystore])
}
return keystoreManager
}
private func initializeweb3() -> web3 {
let endpoint = "https://ropsten.infura.io/v3/....."
let web3 = web3swift.web3(provider: Web3HttpProvider(URL(string: endpoint)!)!)
web3.addKeystoreManager(keystoreManager)
return web3
}
func callSmartContract() {
let value: String = "1"
let walletAddress = EthereumAddress(wallet.address)!
let contractAddress = EthereumAddress("SmartContractAddress")!
let contractMethod = "store"
let contractABI = MyContractABI
let abiVersion = 2
let parameters = [9] as [AnyObject]
let extraData: Data = Data()
let contract = web3.contract(contractABI, at: contractAddress, abiVersion: abiVersion)!
let amount = Web3.Utils.parseToBigUInt(value, units: .wei)
var options = TransactionOptions.defaultOptions
options.value = amount
options.from = walletAddress
options.gasPrice = .automatic
options.gasLimit = .automatic
let tx = contract.write(
contractMethod,
parameters: parameters,
extraData: extraData,
transactionOptions: options)!
do {
let password = "MetamaskPassword"
let result = try tx.send(password: password)
print(result)
} catch {
print("Token Balance failed: \(error)")
}
}
}
Like this should work, I think passing the value/option.value in the smartContract call method isn't necessary, but since I don't have your ABI I prefer to not remove anything from how it worked for me. Also I am not sure about the type of the number you pass.
Feel free to edit if this works without :)
Might I be so inclined to ask for a hand and or different perspectives on how to Unit Test a function on my Viewcontroller that calls an HTTP request to a Back End server using promise kit which returns JSON that is then decoded into the data types needed and then mapped.
This is one of the promise kit functions (called in viewWillAppear) to get stock values etc...
func getVantage(stockId: String) {
firstly {
self.view.showLoading()
}.then { _ in
APIService.Chart.getVantage(stockId: stockId)
}.compactMap {
return $0.dataModel()
}.done { [weak self] data in
guard let self = self else { return }
self.stockValue = Float(data.price ?? "") ?? 0.00
self.valueIncrease = Float(data.delta ?? "") ?? 0.00
self.percentageIncrease = Float(data.deltaPercentage ?? "") ?? 0.00
let roundedPercentageIncrease = String(format: "%.2f", self.percentageIncrease)
self.stockValueLabel.text = "\(self.stockValue)"
self.stockValueIncreaseLabel.text = "+\(self.valueIncrease)"
self.valueIncreasePercentLabel.text = "(+\(roundedPercentageIncrease)%)"
}.ensure {
self.view.hideLoading()
}.catch { [weak self] error in
guard let self = self else { return }
self.handleError(error: error)
}
}
I've thought of using expectations to wait until the promise kit function is called in the unit test like so :
func testChartsMain_When_ShouldReturnTrue() {
//Arange
let sut = ChartsMainViewController()
let exp = expectation(description: "")
let testValue = sut.stockValue
//Act
-> Note : this code down here doesn't work
-> normally a completion block then kicks in and asserts a value then checks if it fulfills the expectation, i'm not mistaken xD
-> But this doesn't work using promisekit
//Assert
sut.getVantage(stockId: "kj3i19") {
XCTAssert((testValue as Any) is Float && !(testValue == 0.0))
exp.fulfill()
}
self.wait(for: [exp], timeout: 5)
}
but the problem is promisekit is done in its own custom chain blocks with .done being the block that returns a value from the request, thus i can't form the completion block on the unit test like in conventional Http requests like :
sut.executeAsynchronousOperation(completion: { (error, data) in
XCTAssertTrue(error == nil)
XCTAssertTrue(data != nil)
testExpectation.fulfill()
})
You seem to have an awful amount of business logic in your view controller, and this is something that makes it harder (not impossible, but harder) to properly test your code.
Recommending to extract all networking and data processing code into the (View)Model of that controller, and expose it via a simple interface. This way your controller becomes as dummy as possible, and doesn't need much unit testing, and you'll be focusing the unit tests on the (view)model.
But that's another, long, story, and I deviate from the topic of this question.
The first thing that prevents you from properly unit testing your function is the APIService.Chart.getVantage(stockId: stockId), since you don't have control over the behaviour of that call. So the first thing that you need to do is to inject that api service, either in the form of a protocol, or in the form of a closure.
Here's the closure approach exemplified:
class MyController {
let getVantageService: (String) -> Promise<MyData>
func getVantage(stockId: String) {
firstly {
self.view.showLoading()
}.then { _ in
getVantageService(stockId)
}.compactMap {
return $0.dataModel()
}.done { [weak self] data in
// same processing code, removed here for clarity
}.ensure {
self.view.hideLoading()
}.catch { [weak self] error in
guard let self = self else { return }
self.handleError(error: error)
}
}
}
Secondly, since the async call is not exposed outside of the function, it's harder to set a test expectation so the unit tests can assert the data once it knows. The only indicator of this function's async calls still running is the fact that the view shows the loading state, so you might be able to make use of that:
let loadingPredicate = NSPredicate(block: { _, _ controller.view.isLoading })
let vantageExpectation = XCTNSPredicateExpectation(predicate: loadingPredicate, object: nil)
With the above setup in place, you can use expectations to assert the behaviour you expect from getVantage:
func test_getVantage() {
let controller = MyController(getVantageService: { _ in .value(mockedValue) })
let loadingPredicate = NSPredicate(block: { _, _ !controller.view.isLoading })
let loadingExpectation = XCTNSPredicateExpectation(predicate: loadingPredicate, object: nil)
controller.getVantage(stockId: "abc")
wait(for: [loadingExpectation], timeout: 1.0)
// assert the data you want to check
}
It's messy, and it's fragile, compare this to extracting the data and networking code to a (view)model:
struct VantageDetails {
let stockValue: Float
let valueIncrease: Float
let percentageIncrease: Float
let roundedPercentageIncrease: String
}
class MyModel {
let getVantageService: (String) -> Promise<VantageDetails>
func getVantage(stockId: String) {
firstly {
getVantageService(stockId)
}.compactMap {
return $0.dataModel()
}.map { [weak self] data in
guard let self = self else { return }
return VantageDetails(
stockValue: Float(data.price ?? "") ?? 0.00,
valueIncrease: Float(data.delta ?? "") ?? 0.00,
percentageIncrease: Float(data.deltaPercentage ?? "") ?? 0.00,
roundedPercentageIncrease: String(format: "%.2f", self.percentageIncrease))
}
}
}
func test_getVantage() {
let model = MyModel(getVantageService: { _ in .value(mockedValue) })
let vantageExpectation = expectation(name: "getVantage")
model.getVantage(stockId: "abc").done { vantageData in
// assert on the data
// fulfill the expectation
vantageExpectation.fulfill()
}
wait(for: [loadingExpectation], timeout: 1.0)
}
I am trying to interact with a smart contract I set up.
Basically the goal is to set from an iOS App 5 Parameters
projectTitle
projectLocation
projectStart
projectEnd
teamType
I want the user to set those parameters and write it on the ropsten testnetwork.
I also would like to get the contract information at a later point whenever the user feels for it.
my solidity code is working properly in remix and the contract is already deployed:
pragma solidity >=0.4.22 <0.7.0;
contract ProjectContent {
string public projectTitle;
string public projectLocation;
string public projectStart;
string public projectEnd;
string public teamType;
function projectContent(string initialProjectTitle, string initialProjectLocation, string initialProjectStart, string initialProjectEnd, string initialTeamType) public {
projectTitle = initialProjectTitle;
projectLocation = initialProjectLocation;
projectStart = initialProjectStart;
projectEnd = initialProjectEnd;
teamType = initialTeamType;
}
function setContract(string newProjectTitle, string newProjectLocation, string newProjectStart, string newProjectEnd, string newTeamType) public {
projectTitle = newProjectTitle;
projectLocation = newProjectLocation;
projectStart = newProjectStart;
projectEnd = newProjectEnd;
teamType = newTeamType;
}
function getProjectTitle() public view returns (string) {
return projectTitle;
}
function getProjectLocation() public view returns (string) {
return projectLocation;
}
function getProjectStart() public view returns (string) {
return projectStart;
}
function getProjectEnd() public view returns (string) {
return projectEnd;
}
function getTeamType() public view returns (string) {
return teamType;
}
}
My problem now is that I cannot figure out how to retrieve the data from the blockchain using the web3swift library. I am doing it like so now:
class ProjectContractViewController: UIViewController, HalfModalPresentable {
#IBOutlet weak var contractABIView: UITextView!
var halfModalTransitioningDelegate: HalfModalTransitioningDelegate?
var contractABI = "[{\"constant\":false,\"inputs\":[{\"name\":\"initialProjectTitle\",\"type\":\"string\"},{\"name\":\"initialProjectLocation\",\"type\":\"string\"},{\"name\":\"initialProjectStart\",\"type\":\"string\"},{\"name\":\"initialProjectEnd\",\"type\":\"string\"},{\"name\":\"initialTeamType\",\"type\":\"string\"}],\"name\":\"projectContent\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"newProjectTitle\",\"type\":\"string\"},{\"name\":\"newProjectLocation\",\"type\":\"string\"},{\"name\":\"newProjectStart\",\"type\":\"string\"},{\"name\":\"newProjectEnd\",\"type\":\"string\"},{\"name\":\"newTeamType\",\"type\":\"string\"}],\"name\":\"setContract\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectEnd\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectLocation\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectStart\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectTitle\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getTeamType\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectEnd\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectLocation\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectStart\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectTitle\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"teamType\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"}]"
let str = "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var contractAddress = EthereumAddress("0x11A0c067d7481240dCA57457eff77fc98dEAdE0F")
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
func callContract(Password: String) {
// Get from address from private key
let formattedKey = Password.trimmingCharacters(in: .whitespacesAndNewlines)
let dataKey = Data.fromHex(formattedKey )!
// ### use [passKey]
let keystore = try! EthereumKeystoreV3(privateKey: dataKey, password: "")!
let keyData = try! JSONEncoder().encode(keystore.keystoreParams)
// let address = keystore.addresses!.first!.address
let address = keystore.addresses!.first!.address
let ethAddress = EthereumAddress(address)
let infura = Web3.InfuraMainnetWeb3()
// 1
let contract = infura.contract(contractABI, at: contractAddress, abiVersion: 2)
// 2
var options = TransactionOptions.defaultOptions
options.from = keystore.addresses!.first!
// 3
let data = Data.init(hex: str)
let transactionIntermediate = contract?.method("getProjectTitle", parameters: [address] as [AnyObject], extraData: data, transactionOptions: options)
// 4
let result = transactionIntermediate!.call(transactionOptions: options)
switch result {
// 5
case .success(let res):
let ans = res["0"] as! Bool
DispatchQueue.main.async {
completion(Result.Success(ans))
}
case .failure(let error):
DispatchQueue.main.async {
completion(Result.Error(error))
}
}
}
}
I get an error for the resultsaying:
"Call can throw, but it is not marked with 'try' and the error is not handled"
and in general I find it really hard to set up the interaction with a smart contract abi.
I am already using the web3swift functionality for sending transactions at it works like a charm.
Maybe someone knows how I can record information on the blockchain and get it using web3swift.
You are close. Starting with the error "Call can throw, but it is not marked with 'try' and the error is not handled" this is caused by trying to call a contract function without using the Try Catch pattern. Do to the way web3 library is designed this pattern is necessary for all write and call methods.
// Incorrect
let result = transactionIntermediate!.call(transactionOptions: options)
// Correct
do {
let result = try transactionIntermediate!.call(transactionOptions: options)
}catch{
print("Error trying to call method \(error)")
}
Additionally, I recommend using the DispatchQueue.main.async along with Promise Kit library when making your contract calls.
ABIs are hard to read and messy, don't recommend using it to help find callable methods and parameters within the contract. Instead I would have the contract open along side Xcode and through the use of either an enum or struct containing all the contract methods that are going to be used.
// Methods available within the contract
enum ContractMethods:String {
case projectContract = "projectContent"
case setContract = "setContract"
case getProjectTitle = "getProjectTitle"
case getProjectLocation = "getProjectLocation"
case getProjectStart = "getProjectStart"
case getProjectEnd = "getProjectEnd"
case getTeamType = "getTeamType"
}
// Usage
ContractMethods.setContract.rawValue
I moved the ABI to a separate file within xcode to keep it clean. Here is link to the file.
Here is a good example to help get you started. Check out my GitHub repo for the improved version.
import UIKit
import web3swift
import PromiseKit
struct Wallet {
let address: String
let data: Data
let name:String
let isHD:Bool
}
struct HDKey {
let name:String?
let address:String
}
var password = "" // leave empty for ganache or use your wallet password
let privateKey = "<PrivateKey>" // Private key of wallet
let walletName = "MyWallet"
let contractAddress = "<ContractAddress>" // 0x11A0c067d7481240dCA57457eff77fc98dEAdE0F
let endpoint = URL(string:"http://127.0.0.1:7545")! // Im using Ganache but it might look like endpoint = URL(string:"https://rinkeby.infura.io/v3/<APIKEY>")!
let abiVersion = 2
class ViewController: UIViewController {
// Mock data used within contract
let projectTitle = "HouseSiding"
let projectLocation = "299 Race Ave. Dacula, GA 30019"
let projectStart = "May 14, 2021"
let projectEnd = "June 15, 2021"
let teamType = "Collaboration"
var web3:web3?
var contract:web3.web3contract?
override func viewDidLoad() {
super.viewDidLoad()
// 1. Create wallet using a private key
let formattedKey = privateKey.trimmingCharacters(in: .whitespacesAndNewlines)
let dataKey = Data.fromHex(formattedKey)!
let keyStore = try! EthereumKeystoreV3(privateKey:dataKey, password: password)!
let keyData = try! JSONEncoder().encode(keyStore.keystoreParams)
let address = keyStore.addresses!.first!.address
let wallet = Wallet(address: address, data: keyData, name: walletName, isHD: false)
// 2. Construct web3 and keystoreManager
do {
web3 = try Web3.new(endpoint)
let data = wallet.data
var keystoreManager: KeystoreManager
if wallet.isHD {
let keystore = BIP32Keystore(data)!
keystoreManager = KeystoreManager([keystore])
}else{
let keystore = EthereumKeystoreV3(data)!
keystoreManager = KeystoreManager([keystore])
}
print(keystoreManager.addresses)
web3!.addKeystoreManager(keystoreManager)
let ethContractAddress = EthereumAddress(contractAddress, ignoreChecksum: true)!
contract = web3!.contract(contractABI, at: ethContractAddress, abiVersion: abiVersion)!
}catch{
print ("Failed to construct contract and/or keystoreManager \(error)")
}
// 3. Create and callout a contract method
//let parameters = [projectTitle,projectLocation,projectStart,projectEnd,teamType] as [AnyObject] // parameters used to created a new project
let parameters = [] as [AnyObject] // no parameters
let response = Promise<Any> { seal in
DispatchQueue.global().async {
// Catch errors within async call
do {
// No extra data for method call
let extraData: Data = Data()
// Options for method call
var options = TransactionOptions.defaultOptions
options.from = EthereumAddress(wallet.address)! // current wallet address
// Leave automatic for gas
options.gasPrice = .automatic
options.gasLimit = .automatic
// Calling get Project title from contract
// NOTE: First call setContract with parameters
let tx = self.contract!.method("getProjectTitle",
parameters: parameters,
extraData: extraData,
transactionOptions: options)
// Depending on the type of call a password might be needed
//if password != nil {
//let result = try tx!.send(password: password)
// seal.resolve(.fulfilled(true))
//}else{
let result = try tx!.call()
// fulfill are result from contract
let anyResult = result["0"] as Any
seal.resolve(.fulfilled(anyResult))
//}
}catch {
// error
seal.reject(error)
}
}
}
response.done({result in
print(result) // Optional(HouseSiding)
})
}
}
I have been experimenting with some new swift architectures and patterns and I have noticed a strange issue with RxSwift where it seems if I am making a service call and an error occurs - e.g. user enters wrong password - then it seems to dispose of my subscriptions so I cannot make the service call again
I am unsure as to why this happening. I made a quick mini project demonstrating the issue with a sample login app.
My ViewModel looks like this
import RxSwift
import RxCocoa
import RxCoordinator
import RxOptional
extension LoginModel : ViewModelType {
struct Input {
let loginTap : Observable<Void>
let password : Observable<String>
}
struct Output {
let validationPassed : Driver<Bool>
let loginActivity : Driver<Bool>
let loginServiceError : Driver<Error>
let loginTransitionState : Observable<TransitionObservables>
}
func transform(input: LoginModel.Input) -> LoginModel.Output {
// check if email passes regex
let isValid = input.password.map{(val) -> Bool in
UtilityMethods.isValidPassword(password: val)
}
// handle response
let loginResponse = input.loginTap.withLatestFrom(input.password).flatMapLatest { password in
return self.service.login(email: self.email, password: password)
}.share()
// handle loading
let loginServiceStarted = input.loginTap.map{true}
let loginServiceStopped = loginResponse.map{_ in false}
let resendActivity = Observable.merge(loginServiceStarted, loginServiceStopped).materialize().map{$0.element}.filterNil()
// handle any errors from service call
let serviceError = loginResponse.materialize().map{$0.error}.asDriver(onErrorJustReturn: RxError.unknown).filterNil()
let loginState = loginResponse.map { _ in
return self.coordinator.transition(to: .verifyEmailController(email : self.email))
}
return Output(validationPassed : isValid.asDriver(onErrorJustReturn: false), loginActivity: resendActivity.asDriver(onErrorJustReturn: false), loginServiceError: serviceError, loginTransitionState : loginState)
}
}
class LoginModel {
private let coordinator: AnyCoordinator<WalkthroughRoute>
let service : LoginService
let email : String
init(coordinator : AnyCoordinator<WalkthroughRoute>, service : LoginService, email : String) {
self.service = service
self.email = email
self.coordinator = coordinator
}
}
And my ViewController looks like this
import UIKit
import RxSwift
import RxCocoa
class TestController: UIViewController, WalkthroughModuleController, ViewType {
// password
#IBOutlet var passwordField : UITextField!
// login button
#IBOutlet var loginButton : UIButton!
// disposes of observables
let disposeBag = DisposeBag()
// view model to be injected
var viewModel : LoginModel!
// loader shown when request is being made
var generalLoader : GeneralLoaderView?
override func viewDidLoad() {
super.viewDidLoad()
}
// bindViewModel is called from route class
func bindViewModel() {
let input = LoginModel.Input(loginTap: loginButton.rx.tap.asObservable(), password: passwordField.rx.text.orEmpty.asObservable())
// transforms input into output
let output = transform(input: input)
// fetch activity
let activity = output.loginActivity
// enable/disable button based on validation
output.validationPassed.drive(loginButton.rx.isEnabled).disposed(by: disposeBag)
// on load
activity.filter{$0}.drive(onNext: { [weak self] _ in
guard let strongSelf = self else { return }
strongSelf.generalLoader = UtilityMethods.showGeneralLoader(container: strongSelf.view, message: .Loading)
}).disposed(by: disposeBag)
// on finish loading
activity.filter{!$0}.drive(onNext : { [weak self] _ in
guard let strongSelf = self else { return }
UtilityMethods.removeGeneralLoader(generalLoader: strongSelf.generalLoader)
}).disposed(by: disposeBag)
// if any error occurs
output.loginServiceError.drive(onNext: { [weak self] errors in
guard let strongSelf = self else { return }
UtilityMethods.removeGeneralLoader(generalLoader: strongSelf.generalLoader)
print(errors)
}).disposed(by: disposeBag)
// login successful
output.loginTransitionState.subscribe().disposed(by: disposeBag)
}
}
My service class
import RxSwift
import RxCocoa
struct LoginResponseData : Decodable {
let msg : String?
let code : NSInteger
}
class LoginService: NSObject {
func login(email : String, password : String) -> Observable<LoginResponseData> {
let url = RequestURLs.loginURL
let params = ["email" : email,
"password": password]
print(params)
let request = AFManager.sharedInstance.setupPostDataRequest(url: url, parameters: params)
return request.map{ data in
return try JSONDecoder().decode(LoginResponseData.self, from: data)
}.map{$0}
}
}
If I enter valid password, request works fine. If I remove the transition code for testing purposes, I could keep calling the login service over and over again as long as password is valid. But as soon as any error occurs, then the observables relating to the service call get disposed of so user can no longer attempt the service call again
So far the only way I have found to fix this is if any error occurs, call bindViewModel again so subscriptions are setup again. But this seems like very bad practice.
Any advice would be much appreciated!
At the place where you make the login call:
let loginResponse = input.loginTap
.withLatestFrom(input.password)
.flatMapLatest { [unowned self] password in
self.service.login(email: self.email, password: password)
}
.share()
You can do one of two things. Map the login to a Result<T> type.
let loginResponse = input.loginTap
.withLatestFrom(input.password)
.flatMapLatest { [unowned self] password in
self.service.login(email: self.email, password: password)
.map(Result<LoginResponse>.success)
.catchError { Observable.just(Result<LoginResponse>.failure($0)) }
}
.share()
Or you can use the materialize operator.
let loginResponse = input.loginTap
.withLatestFrom(input.password)
.flatMapLatest { [unowned self] password in
self.service.login(email: self.email, password: password)
.materialize()
}
.share()
Either method changes the type of your loginResponse object by wrapping it in an enum (either a Result<T> or an Event<T>. You can then deal with errors differently than you do with legitimate results without breaking the Observable chain and without loosing the Error.
Another option, as you have discovered is to change the type of loginResponse to an optional but then you loose the error object.
The behavior is not strange, but works as expected: As stated in the official RxSwift documentation documentation:
"When a sequence sends the completed or error event all internal resources that compute sequence elements will be freed."
For your example that means, a failed login attempt, will cause method func login(email : String, password : String) -> Observable<LoginResponseData> to return an error, i.e. return Observable<error>, which will:
on the one hand fast forward this error to all its subscribers (which will be done your VC)
on the other hand dispose the observable
To answer your question, what you can do other than subscribing again, in order to maintain the subscription: You could just make use of .catchError(), so the observable does not terminate and you can decide yourself what you want to return after an error occurs. Note, that you can also check the error for a specific error domain and return errors only for certain domains.
I personally see the responsibility of the error handling in the hand of the respective subscribers, i.e. in your case your TestController (so you could use .catchError() there), but if you want to be sure the observable returned from from func login(email : String, password : String) -> Observable<LoginResponseData> does not even fast forward any errors for all subscriptions, you could also use .catchError() here, although I'd see issues for potential misbehaviors.