快4.倍

把这些放到文件中:

func background(work: @escaping () -> ()) {
    DispatchQueue.global(qos: .userInitiated).async {
        work()
    }
}

func main(work: @escaping () -> ()) {
    DispatchQueue.main.async {
        work()
    }
}

然后在需要的地方调用它:

background {
     //background job
     main {
       //update UI (or what you need to do in main thread)
     }
}

在我们的iOS应用中，中央调度是用来处理多任务的。

您可以使用此代码

// Using time interval

DispatchQueue.main.asyncAfter(deadline: DispatchTime.now()+1) {
    print("Hello World")
}

// Background thread
queue.sync {
     for i in 0..<10 {
          print("Hello", i)
     }
}

// Main thread
for i in 20..<30 {
     print("Hello", i)
}

更多信息请访问这个链接:https://www.programminghub.us/2018/07/integrate-dispatcher-in-swift.html

Swift 3版本

Swift 3利用新的DispatchQueue类来管理队列和线程。要在后台线程上运行一些东西，你可以使用:

let backgroundQueue = DispatchQueue(label: "com.app.queue", qos: .background)
backgroundQueue.async {
    print("Run on background thread")
}

或者如果你想在两行代码中实现:

DispatchQueue.global(qos: .background).async {
    print("Run on background thread")

    DispatchQueue.main.async {
        print("We finished that.")
        // only back on the main thread, may you access UI:
        label.text = "Done."
    }
}

你也可以在本教程中获得一些关于Swift 3中GDC的深入信息。

多用途螺纹功能

public enum QueueType {
        case Main
        case Background
        case LowPriority
        case HighPriority

        var queue: DispatchQueue {
            switch self {
            case .Main:
                return DispatchQueue.main
            case .Background:
                return DispatchQueue(label: "com.app.queue",
                                     qos: .background,
                                     target: nil)
            case .LowPriority:
                return DispatchQueue.global(qos: .userInitiated)
            case .HighPriority:
                return DispatchQueue.global(qos: .userInitiated)
            }
        }
    }

    func performOn(_ queueType: QueueType, closure: @escaping () -> Void) {
        queueType.queue.async(execute: closure)
    }

像这样使用它:

performOn(.Background) {
    //Code
}

Swift 3.0 +

在Swift 3.0中，很多东西都被现代化了。在后台队列上运行一些东西看起来像这样:

DispatchQueue.global(qos: .userInitiated).async {
    print("This is run on a background queue")

    DispatchQueue.main.async {
        print("This is run on the main queue, after the previous code in outer block")
    }
}

Swift 1.2到2.3

let qualityOfServiceClass = QOS_CLASS_USER_INITIATED
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
    print("This is run on a background queue")

    dispatch_async(dispatch_get_main_queue(), { () -> Void in
        print("This is run on the main queue, after the previous code in outer block")
    })
})

Pre Swift 1.2 -已知问题

从Swift 1.1开始，苹果在没有做一些修改的情况下不支持上述语法。传递qos_class_user_initialized实际上不起作用，而是使用Int(qos_class_user_initialized .value)。

有关更多信息，请参阅apple文档

来自Jameson Quave的教程

斯威夫特2

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
    //All stuff here
})