ios - How to load view after Alamofire finished its job?

Question

• My Issue:

I am trying to load data from Server, through Alamofire, before SubViewController Load its view. After writing the code, I failed to solve the problem of Async Feature of Alamofire. The view is always be loaded in the SubViewController before Alamofire finished its job.

• Part Of My Code:

ParentViewController:

Leading the way to SubViewController through PrepareForSegue().

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    if segue.identifier == "CellDetailSegue" {
        if let indexPaths = self.dateCollectionView.indexPathsForSelectedItems() {
            let subViewController = segue.destinationViewController as! SubViewConroller
    }
}

SubViewController:

Test whether the data has been loaded by print() in the its viewDidLoad() and load the data by dataRequest() in viewWillAppear()

class SubViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    var availablePeriods401 = [String]()
    var availablePeriods403 = [String]()
    var availablePeriods405 = [String]()

    override func viewDidLoad() {
        super.viewDidLoad() 
        self.dataRequest(self.availablePeriods401)
        self.dataRequest(self.availablePeriods403)
        self.dataRequest(self.availablePeriods405)
        print(self.availablePeriods401.count)
        print(self.availablePeriods403.count)
        print(self.availablePeriods405.count)    
    }

    func dataRequest(_ target: [String]) {
      Alamofire.request(.POST, "http://httpbin.org/get", parameters: ["foo": "bar"]).responseJSON {
            .
            .
            .
      target = Result
      }
   }

 }

• Problem Description:

Three variables in the SubViewController can not be assigned the valid values after view was loaded.

Three Outputs' results are all 0.

But I can get valid count if I set print() in the dataRequest().

• My Question:

How to make sure that Alamofire finishes its job?

Where Shall I put the Alamofire Request Function? viewWillApper()? viewDidApper()?

Should I even finished requesting job in ParentViewController's PrepareForSegue() ?

Please teach me how to solve this problem.

A big appreciation for your guide and time.

Ethan Joe

Answer 1

You should call Alamofire Request Function in viewDidLoad function. and you should reload table data when you got response from completion block(from where you print the data).

You can reload tableview like,

 self.tableView.reloadData()

hope this will help :)