iOS 開發多線程 —— NSOperation,iosnsoperation

來源:互聯網
上載者:User

iOS 開發多線程 —— NSOperation,iosnsoperation
本文是根據文頂頂老師的部落格學習而來,轉載地址:http://www.cnblogs.com/wendingding/p/3809042.html一、NSOperation簡介

1.簡單說明

NSOperation的作⽤:配合使用NSOperation和NSOperationQueue也能實現多線程編程

NSOperation和NSOperationQueue實現多線程的具體步驟:

(1)先將需要執行的操作封裝到一個NSOperation對象中

(2)然後將NSOperation對象添加到NSOperationQueue中

(3)系統會⾃動將NSOperationQueue中的NSOperation取出來

(4)將取出的NSOperation封裝的操作放到⼀條新線程中執⾏

 2.NSOperation的子類

NSOperation是個抽象類別,並不具備封裝操作的能力,必須使⽤它的子類

使用NSOperation⼦類的方式有3種:

(1)NSInvocationOperation

(2)NSBlockOperation

(3)自訂子類繼承NSOperation,實現內部相應的⽅法

 

NSInvocationOperation:

範例程式碼:

- (void)viewDidLoad {    [super viewDidLoad];        NSInvocationOperation *operation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(thread1) object:nil];    [operation start];    NSInvocationOperation *operation2 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(thread2) object:nil];    [operation2 start];    }-(void)thread1{    NSLog(@"currentThread = %@",[NSThread currentThread]);}-(void)thread2{   NSLog(@"currentThread2 = %@",[NSThread currentThread]);}
 currentThread = <NSThread: 0x17406d780>{number = 1, name = main}currentThread2 = <NSThread: 0x17406d780>{number = 1, name = main}

可以看見,並沒有開啟新的線程.

注意:操作對象預設在主線程中執行,只有添加到隊列中才會開啟新的線程。即預設情況下,如果操作沒有放到隊列中queue中,都是同步執行。只有將NSOperation放到一個NSOperationQueue中,才會非同步執行操作 

 

NSBlockOperation:
 NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"operation = %@",[NSThread currentThread]);    }];    [operation3 start];看列印結果:operation = <NSThread: 0x1700728c0>{number = 1, name = main}

注意:只要NSBlockOperation封裝的運算元 > 1,就會非同步執行操作

例如:

NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"operation = %@",[NSThread currentThread]);    }];    [operation3 addExecutionBlock:^{        NSLog(@"operation2 = %@",[NSThread currentThread]);    }];    [operation3 start];然後看列印結果:operation = <NSThread: 0x1700706c0>{number = 1, name = main}operation2 = <NSThread: 0x170075a40>{number = 4, name = (null)}

 

NSOperationQueue:

NSOperationQueue的作⽤:NSOperation可以調⽤start⽅法來執⾏任務,但預設是同步執行的

如果將NSOperation添加到NSOperationQueue(操作隊列)中,系統會自動非同步執行NSOperation中的操作

添加操作到NSOperationQueue中,自動執行操作,自動開啟線程

 

樣本:

- (void)viewDidLoad {    [super viewDidLoad];        NSInvocationOperation *operation1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(thread1) object:nil];    NSInvocationOperation *operation2 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(thread2) object:nil];               NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"currentThread3 = %@",[NSThread currentThread]);    }];        [operation3 addExecutionBlock:^{        NSLog(@"currentThread3_1 = %@",[NSThread currentThread]);    }];        NSOperationQueue *queue = [[NSOperationQueue alloc]init];    //把操作添加到隊列中    //第一種方式    [queue addOperation:operation1];    [queue addOperation:operation2];    [queue addOperation:operation3];    //第二種方式    [queue addOperationWithBlock:^{        NSLog(@"currentThread4 = %@",[NSThread currentThread]);    }];    }-(void)thread1{    NSLog(@"currentThread1 = %@",[NSThread currentThread]);}-(void)thread2{   NSLog(@"currentThread2 = %@",[NSThread currentThread]);}

查看結果:

currentThread1 = <NSThread: 0x17006f440>{number = 4, name = (null)}currentThread2 = <NSThread: 0x17007d9c0>{number = 5, name = (null)}currentThread3_1 = <NSThread: 0x17007d9c0>{number = 5, name = (null)}currentThread3 = <NSThread: 0x17006f440>{number = 4, name = (null)}currentThread4 = <NSThread: 0x17007d9c0>{number = 5, name = (null)}

 

相關文章

聯繫我們

該頁面正文內容均來源於網絡整理,並不代表阿里雲官方的觀點,該頁面所提到的產品和服務也與阿里云無關,如果該頁面內容對您造成了困擾,歡迎寫郵件給我們,收到郵件我們將在5個工作日內處理。

如果您發現本社區中有涉嫌抄襲的內容,歡迎發送郵件至: info-contact@alibabacloud.com 進行舉報並提供相關證據,工作人員會在 5 個工作天內聯絡您,一經查實,本站將立刻刪除涉嫌侵權內容。

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.