Call web services by alamofire respectively - ios

Question

I'm creating an application that should call some web services in the begging of the app.
I've wrote a WebServiceManager that contains methods for calling web services and return result in completionHandler, here is one method of WebServiceManager:
extension WebServiceManager {
func checkVersion(completionHandler: #escaping (CheckVersionResponse?, Error?) -> ()) {
sessionManager?.adapter = BaseClientInterceptor()
let appVersion = Bundle.main.infoDictionary!["CFBundleShortVersionString"] as! String
let buildNumber = Bundle.main.infoDictionary!["CFBundleVersion"] as! String
sessionManager?.request(Config.VERSION_URL + "/\(appVersion)/\(buildNumber)" + Config.STATUS, method: .get).responseData { response in
print(response.response?.statusCode)
switch response.result {
case .success(let value):
print("----WS: checkVersion Success-----")
let value = JSON(value)
print(value)
let response = CheckVersionResponse(responseCode: response.response?.statusCode ?? -1)
if (response.getResponseCode() == 200) {
response.setUrl(value["url"].string ?? "")
response.setNow(value["now"].intValue)
response.setStatus(value["status"].stringValue)
response.setMessage(value["message"].stringValue)
}
completionHandler(response, nil)
case .failure(let error):
print(error)
print("----WS: checkVersion Failed-----")
completionHandler(nil, error)
}
}
}
}
and I use some methods of this manager in SplashScreenViewController:
class SplashViewController: UIViewController {
override func viewDidAppear(_ animated: Bool) {
WebServiceManager.shared.checkVersion() { response, error in
//...
}
WebServiceManager.shared.getCurrentDate() { response, error in
//...
}
WebServiceManager.shared.getUpdatedKeyValues() { response, error in
//...
}
if !UserDefaults.standard.bool(forKey: "hasRegistered") {
self.performSegue(withIdentifier: "ToRegistration", sender: self)
} else {
self.performSegue(withIdentifier: "ToMain", sender: self)
}
}
}
I expect that this method runs line by line but it goes through to if at first.
How can I call these web services in order then make a decision based on UserDefaults values ?

Answer 1

sessionManager.request methods are asynchronous, so they will not execute synchronously (line by line) on viewDidAppear (by the way you are missing super.viewDidAppear())
If you want some code to execute after those 3 services you can do something like this, not sure if its the best solution tho:
class SplashViewController: UIViewController {
private var allDone = 0
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
WebServiceManager.shared.checkVersion() { response, error in
//...
checkUserDefault()
}
WebServiceManager.shared.getCurrentDate() { response, error in
//...
checkUserDefault()
}
WebServiceManager.shared.getUpdatedKeyValues() { response, error in
//...
checkUserDefault()
}
}
private func checkUserDefault() {
allDone += 1
/// When all 3 services are finish
if allDone == 3 {
if !UserDefaults.standard.bool(forKey: "hasRegistered") {
self.performSegue(withIdentifier: "ToRegistration", sender: self)
} else {
self.performSegue(withIdentifier: "ToMain", sender: self)
}
}
}
}
Hope it helps you!
EDIT: This is the simplest solution based on your existing code, if you want to do it 'the right way' you may want to check Promises: http://khanlou.com/2016/08/promises-in-swift/ https://www.raywenderlich.com/9208-getting-started-with-promisekit
You need to use PromiseKit and do something like this:
Replace your API methods so they use Promise as a response:
func checkVersion() -> Promise<CheckVersionResponse> {
sessionManager?.adapter = BaseClientInterceptor()
let appVersion = Bundle.main.infoDictionary!["CFBundleShortVersionString"] as! String
let buildNumber = Bundle.main.infoDictionary!["CFBundleVersion"] as! String
// Return a Promise for the caller of this function to use.
return Promise { fulfill, reject in
// Inside the Promise, make an HTTP request
sessionManager?.request(Config.VERSION_URL + "/\(appVersion)/\(buildNumber)" + Config.STATUS, method: .get).responseData { response in
print(response.response?.statusCode)
switch response.result {
case .success(let value):
print("----WS: checkVersion Success-----")
let value = JSON(value)
print(value)
let response = CheckVersionResponse(responseCode: response.response?.statusCode ?? -1)
if (response.getResponseCode() == 200) {
response.setUrl(value["url"].string ?? "")
response.setNow(value["now"].intValue)
response.setStatus(value["status"].stringValue)
response.setMessage(value["message"].stringValue)
}
fulfill(response)
case .failure(let error):
print(error)
print("----WS: checkVersion Failed-----")
reject(error)
}
}
}
}
Then on the UIViewController call the WebServiceManager methods like this:
WebServiceManager.shared.checkVersion().then { response in
// ....
WebServiceManager.shared.getCurrentDate()
}.then { date in
// ...
WebServiceManager.shared.getUpdatedKeyValues()
}.catch { error in
print(error)
}