swift 多线程，CocoaOperation,Operation + OperationQueue

 两个都是面向对象的

取消，依赖，优先级处理，复杂逻辑，保存业务状态，子类化

Operation分为两类

• Operation

相当于父类

• BlockOperation

继承父类 可以用传递闭包进行操作

Opreation

分别有四种状态

1. isReady
2. isExecuting
3. isFinished
4. isCancelled

运行状态有两种

• sync 同步 

需要实现main（）方法

• async 异步 （网络操作）

 start() 开启线程方法

isAsynchronous  是否异步

isExecuting 是否执行中

isFinished  是否结束

可以添加或者删除依赖 

addDependency(Operation)

reoveDependency(Operation)

denpendencies:[Operation] 

也就是另外的一个Operation执行完毕后才能执行当前的operation

OpreationQueue

1. OperationQueue队列里可以加入很多个Operation，可以把OperationQueue看做一个线程池，可往线程池中添加操作（Operation）到队列中
2. 底层使用GCD
3. maxConcurremtOperationCount可以设置最大并发数
4. defalutMaxConturrenOperationCount 根据当前系统条件确定的最大并发数
5. 可以取消所有Operation,但是当前正在执行的不会取消。
6. 所有Operation执行完毕后退出销毁

BlockOperation

code

//: FROM  https://www.anuomob.com

import UIKit
import PlaygroundSupport
//不希望主线程执行完毕就结束
PlaygroundPage.current.needsIndefiniteExecution = true
class ObjectForThread{
    func threadTest(){
        let operation = BlockOperation(block: {[weak self] in
            self?.threadWorker()
            return
            
        })
        let queue=OperationQueue()
        queue.addOperation(operation)
        print("threadTest")
    }
    
    @objc func threadWorker(){
        print("threadWorker")
    }
}

let obj = ObjectForThread()
obj.threadTest()

继承Operation

//: FROM  https://www.anuomob.com

import UIKit
import PlaygroundSupport
//不希望主线程执行完毕就结束
PlaygroundPage.current.needsIndefiniteExecution = true
class ObjectForThread{
    func threadTest(){
        let operation = MyOperation()
        let queue = OperationQueue()
        queue.addOperation(operation)
        print("threadTest")
    }
        
      
}

class MyOperation:Operation{
    override func main() {
        sleep(1)
        print("MyOperation")
    }
    
}
let obj = ObjectForThread()
obj.threadTest()

Opeartion 完成的回调

completionBlock

//: FROM  https://www.anuomob.com

import UIKit
import PlaygroundSupport
//不希望主线程执行完毕就结束
PlaygroundPage.current.needsIndefiniteExecution = true
class ObjectForThread{
    func threadTest(){
        let operation = MyOperation()
        operation.completionBlock = {()-> Void in
            print("--operation.completionBlock--")
        }
        let queue = OperationQueue()
        queue.addOperation(operation)
        print("threadTest")

    }
        
      
}

class MyOperation:Operation{
    override func main() {
        sleep(1)
        print("MyOperation")
    }
    
}
let obj = ObjectForThread()
obj.threadTest()