CODEWITHSUNDEEP
iosswiftuitableview
Anilkumar iOS Developer
Anilkumar iOS Developer

Reputation: 3745

How to call 20 webservices at same time in iOS with Swift?

In my application I have a requirement to get the response before loading the tableview. I need to call around 20 API's at same time. And each API data need to show each 1 cell in tableview.

I need to call them in Viewdidload method which calls before tableview methods.

Can anyone guide or provide some useful example to do this?

Upvotes: 1

Views: 407

Answers (2)

JPetric
JPetric

Reputation: 3918

You should use dispatch groups like this:

let group = DispatchGroup()

group.enter()
networkCall1 {
    // response received
    group.leave()
}

group.enter()
networkCall2 {
    // response received
    group.leave()
}

group.notify(queue: DispatchQueue.main, execute: {
    // this will be notified only when there is no one left in the group
})

Before a network call you enter a group. When you receive a response you leave the group and when there is no one left in the group, group.notify block will execute.

This is just a simple explanation, you should read more about it to fully understand how it works.

Upvotes: 1

Tim Bernikovich
Tim Bernikovich

Reputation: 5945

My suggestion is to use GCD's groups for that.

let backgroundQueue = DispatchQueue.global(attributes: .qosDefault)
let group = DispatchGroup()

var dataForTable:[String] = []
for number in 0..<n {
    group.enter()
    // Do your request with async callback, append data and leave GCD group.
    backgroundQueue.async(group: group, execute: {
        let newData = String()  
        dataForTable.append(newData)
        group.leave()
    })
}

group.notify(queue: DispatchQueue.main, execute: {
    print("All requests data")
    self.tableViewData = dataForTable
    self.tableView.reloadData()
})

Upvotes: 1

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