Swift: Calling ViewDidLoad recursively due to URLSession.DataTask

Question

I am having trouble populating a scene with a list of images. I am using UIViewController and not a tableView to display my interface. Imagine Tinder like application. No tableview. To scroll through the images, each images are being swiped to the next.

The way I populate the images on the scene is by making a POST request inside ViewDidLoad using URLSession.DataTask. But I am having trouble with what seem like a multi threading issues.

Original code:

ViewDidLoad(){
        queryService.getProduct { productlist, errorMessage in

            if !errorMessage.isEmpty { print("Search error: " + errorMessage) }

            self.products = productlist
        }

        // CODE TO initialize View
        // MORE CODE
}

queryService contains URLSession.DataTask which calls the URL and carries out Serialization. That method has been implemented correctly. The problem I am facing is that self.products get instantiated after "CODE TO initialize View" section. They both seem to be running in parallel. So here is what I did to remedy the fix:

Quick fix:

var count = 0
ViewDidLoad(){
     if count == 0 {
        queryService.getProduct { productlist, errorMessage in

            if !errorMessage.isEmpty { print("Search error: " + errorMessage) }

            self.products = productlist
            self.count = 1
            self.ViewDidLoad()
        }
     } else {
        // CODE TO initialize View
        // MORE CODE
     }
}

This works but I know my quick fix is not the best practice. Any advice on the most optimal solution? Thanks. Also a follow up question: Is it okay to call viewdidload manually like this?

Answer 1

You can do this function but not in `viewDidLoad

override func viewDidLoad() {
    super.viewDidLoad()
    getProductUntilThereIsOneProductAtLeast()
}

func getProductUntilThereIsOneProductAtLeast() {
    if count == 0 {
        queryService.getProduct { productlist, errorMessage in

            if !errorMessage.isEmpty { print("Search error: " + errorMessage) }

            self.products = productlist
            self.count = 1
            self.getProductUntilThereIsOneProductAtLeast()
        }
    } else {
        // CODE TO initialize View
        // MORE CODE
    }
}