How to create dispatch queue in Swift 3

Question

In Swift 2, I was able to create queue with the following code:

let concurrentQueue = dispatch_queue_create(\"com.swift3.imageQueue\", DISPATCH_QUEUE_CONCURR         


        

Answer 1

I did this and this is especially important if you want to refresh your UI to show new data without user noticing like in UITableView or UIPickerView.

    DispatchQueue.main.async
 {
   /*Write your thread code here*/
 }

Answer 2

DispatchQueue.main.async(execute: {

// write code

})

Serial Queue :

let serial = DispatchQueue(label: "Queuename")

serial.sync { 

 //Code Here

}

Concurrent queue :

 let concurrent = DispatchQueue(label: "Queuename", attributes: .concurrent)

concurrent.sync {

 //Code Here
}

Answer 3

Since the OP question has already been answered above I just want to add some speed considerations:

It makes a lot of difference what priority class you assign to your async function in DispatchQueue.global.

I don't recommend running tasks with the .background thread priority especially on the iPhone X where the task seems to be allocated on the low power cores.

Here is some real data from a computationally intensive function that reads from an XML file (with buffering) and performs data interpolation:

Device name / .background / .utility / .default / .userInitiated / .userInteractive

1. iPhone X: 18.7s / 6.3s / 1.8s / 1.8s / 1.8s
2. iPhone 7: 4.6s / 3.1s / 3.0s / 2.8s / 2.6s
3. iPhone 5s: 7.3s / 6.1s / 4.0s / 4.0s / 3.8s

Note that the data set is not the same for all devices. It's the biggest on the iPhone X and the smallest on the iPhone 5s.