parallel in swift

In Swift, parallel programming can be achieved through concurrency, which is handled by the Grand Central Dispatch (GCD) framework. GCD allows developers to execute tasks asynchronously and concurrently.

To use GCD, we first need to define a dispatch queue. A dispatch queue is responsible for managing the tasks that are submitted to it. These queues can run tasks either concurrently or serially, and the system provides four different types of queues:

• Main queue (serial queue)
• Global queue (concurrent queue)
• Private queue (serial queue)
• Custom queue (can be serial or concurrent)

Here is an example of how we can create a global concurrent queue and execute a task asynchronously:

main.swift
let queue = DispatchQueue.global(qos: .userInteractive)

queue.async {
   // Perform long running task here
}
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In the above code, we are creating a global queue with a quality-of-service (QoS) level of .userInteractive. This tells the system to execute this task with high priority. The async function is used to asynchronously execute the block of code inside the closure.

We can also use a private serial queue to execute a task serially:

main.swift
let queue = DispatchQueue(label: "com.example.myqueue")

queue.sync {
   // Perform long running task here
}
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In this example, we are creating a private serial queue with the label "com.example.myqueue" and using the sync function to execute the block of code inside the closure synchronously. This means that the code will not continue until the task inside the closure is finished.

Overall, GCD provides a flexible and powerful way to perform parallel programming in Swift.