개발도구 : xcode 9.4

언어 및 버전 : swift 4.1

swift 병렬 프로그래밍(Concurrency Programming)

• Thread
• operationQueue
• GCD(Grand Centeral Dispatch)

1. Thread

쓰레드 선언은 다음과 같다.

let thread_one = Thread(target: self, selector: #selector(ViewController.runLoop_one), object: nil)

thread_one.start()

let thread_two = Thread(target: self, selector: #selector(ViewController.runLoop_two), object: nil)

thread_two.start()

let thread_three = Thread(target: self, selector: #selector(ViewController.runLoop_three), object: nil)

thread_three.start()

등록한 쓰레드 셀렉터(단순 숫자 카운트)

@objc func runLoop_one() {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

          print("[thread one] : " + String(nLoop))

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 1)

    }

}

@objc func runLoop_two() {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

         print("[thread two] : " + String(nLoop))

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 1)

    }

}

@objc func runLoop_three() {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

         print("[thread three] : " + String(nLoop)) 

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 1)

    }

}

2. operationQueue

let operationQueue: OperationQueue = OperationQueue()

operationQueue.addOperation {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

         print("[operationQueue one] : " + String(nLoop))

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 0.2)

    }

}

operationQueue.addOperation {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

         print("[operationQueue two] : " + String(nLoop))

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 0.2)

    }

}

operationQueue.addOperation {

    let nCountLimit = 100

    var nLoop = 0

    while(nLoop < nCountLimit){

         print("[operationQueue three] : " + String(nLoop))

         nLoop = nLoop + 1

         Thread.sleep(forTimeInterval: 0.2)

    }

}

3. GCD Dispatch

• main
• global
• custom

3.1. main

라벨과 같은 UI 객체를 컨드롤 할 수 있습니다. 

DispatchQueue.main.async {

    for i in 1...100 {

         self.m_strNum_1.text = String(i)

    }

}

3.2. global

DispatchQueue.global().async {

    for i in 1...100 {

        print("[DispatchQueue global] = \(i)")

    }

}

3.3. custom

DispatchQueue(label: "my define queue").async {

    for i in 1...100 {

         print("[my define queue] = \(i)")

    }

}

4. sync와 async

let globalQueue = DispatchQueue.global()        

globalQueue.async {

    for i in 1...100 {

                print("[DispatchQueue global async one] = \(i)")

    }        

}         

globalQueue.async {

    for i in 1...100 {

                print("[DispatchQueue global async two] = \(i)")

    }        

}         

globalQueue.async {

    for i in 1...100 {

         print("[DispatchQueue global async three] = \(i)")

    }        

}         

globalQueue.sync {

     for i in 1...100 {

         print("[DispatchQueue global sync one] = \(i)")

     }        

}         

globalQueue.sync {

    for i in 1...100 {

         print("[DispatchQueue global sync two] = \(i)")

    }        

}         

globalQueue.sync {

            for i in 1...100 {

                print("[DispatchQueue global sync three] = \(i)")

            }        

}

5. 여러 쓰레드를 묶어서 처리할 수 있습니다.

• wait
• notify

5.1. wait 사용

let group = DispatchGroup()        

group.enter()        

DispatchQueue.global().async {

    for i in 1...100 {

         print("[DispatchQueue global async one] = \(i)")

    }

    group.leave()        

}         

group.enter()        

DispatchQueue.global().async {

    for i in 1...100 {

         print("[DispatchQueue global async two] = \(i)")

    }

    group.leave()        

}         

group.wait(timeout: .distantFuture)        

print("two thread end")

5.2. notify 사용

let group = DispatchGroup()        

let queue = DispatchQueue.global()        

queue.async(group: group) {

    for i in 1...100 {

         print("[DispatchQueue global async one] = \(i)")

    }        

}        

queue.async(group: group) {

    for i in 1...100 {

         print("[DispatchQueue global async two] = \(i)")

    }        

}         

group.notify(queue: DispatchQueue.global()) {

    print("two thread end")        

}