首页 > 代码库 > iOS开发多线程篇—NSOperation简单介绍
iOS开发多线程篇—NSOperation简单介绍
iOS开发多线程篇—NSOperation简单介绍
一、NSOperation简介
1.简单说明
NSOperation的作?:配合使用NSOperation和NSOperationQueue也能实现多线程编程
NSOperation和NSOperationQueue实现多线程的具体步骤:
(1)先将需要执行的操作封装到一个NSOperation对象中
(2)然后将NSOperation对象添加到NSOperationQueue中
(3)系统会?动将NSOperationQueue中的NSOperation取出来
(4)将取出的NSOperation封装的操作放到?条新线程中执?
2.NSOperation的子类
NSOperation是个抽象类,并不具备封装操作的能力,必须使?它的子类
使用NSOperation?类的方式有3种:
(1)NSInvocationOperation
(2)NSBlockOperation
(3)自定义子类继承NSOperation,实现内部相应的?法
二、 具体说明
1.NSInvocationOperation子类
创建对象和执行操作:
1 //创建操作对象,封装要执行的任务2 //NSInvocationOperation 封装操作3 NSInvocationOperation *operation=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test) object:nil];4 5 //执行操作6 [operation start];
说明:一旦执?操作,就会调用target的test方法
代码示例:
1 // 2 // YYViewController.m 3 // 01-NSOperation基本1 4 // 5 // Created by 孔医己 on 14-6-25. 6 // Copyright (c) 2014年 itcast. All rights reserved. 7 // 8 9 #import "YYViewController.h"10 11 @interface YYViewController ()12 13 @end14 15 @implementation YYViewController16 17 - (void)viewDidLoad18 {19 [super viewDidLoad];20 21 //NSOperation:抽象类,不具备封装功能22 23 //创建操作对象,封装要执行的任务24 //NSInvocationOperation 封装操作25 NSInvocationOperation *operation=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test) object:nil];26 27 //执行操作28 [operation start];29 30 }31 32 -(void)test33 {34 35 NSLog(@"--test--%@--",[NSThread currentThread]);36 }37 @end
打印查看:
注意:操作对象默认在主线程中执行,只有添加到队列中才会开启新的线程。即默认情况下,如果操作没有放到队列中queue中,都是同步执行。只有将NSOperation放到一个NSOperationQueue中,才会异步执行操作
2.NSBlockOperation子类
创建对象和添加操作:
1 //创建NSBlockOperation操作对象 2 NSBlockOperation *operation=[NSBlockOperation blockOperationWithBlock:^{ 3 //...... 4 }]; 5 6 //添加操作 7 [operation addExecutionBlock:^{ 8 //.... 9 }];10
代码示例:
代码1:
1 // 2 // YYViewController.m 3 // 02-NSTherad基本2 4 // 5 // Created by 孔医己 on 14-6-25. 6 // Copyright (c) 2014年 itcast. All rights reserved. 7 // 8 9 #import "YYViewController.h"10 11 @interface YYViewController ()12 13 @end14 15 @implementation YYViewController16 17 - (void)viewDidLoad18 {19 [super viewDidLoad];20 21 //创建NSBlockOperation操作对象22 NSBlockOperation *operation=[NSBlockOperation blockOperationWithBlock:^{23 NSLog(@"NSBlockOperation------%@",[NSThread currentThread]);24 }];25 26 27 //开启执行操作28 [operation start];29 }30 @end
打印查看:
代码2:
1 // 2 // YYViewController.m 3 // 02-NSTherad基本2 4 // 5 // Created by 孔医己 on 14-6-25. 6 // Copyright (c) 2014年 itcast. All rights reserved. 7 // 8 9 #import "YYViewController.h"10 11 @interface YYViewController ()12 13 @end14 15 @implementation YYViewController16 17 - (void)viewDidLoad18 {19 [super viewDidLoad];20 21 //创建NSBlockOperation操作对象22 NSBlockOperation *operation=[NSBlockOperation blockOperationWithBlock:^{23 NSLog(@"NSBlockOperation------%@",[NSThread currentThread]);24 }];25 26 //添加操作27 [operation addExecutionBlock:^{28 NSLog(@"NSBlockOperation1------%@",[NSThread currentThread]);29 }];30 31 [operation addExecutionBlock:^{32 NSLog(@"NSBlockOperation2------%@",[NSThread currentThread]);33 }];34 35 //开启执行操作36 [operation start];37 }38 @end
注意:只要NSBlockOperation封装的操作数 > 1,就会异步执行操作
3.NSOperationQueue
NSOperationQueue的作?:NSOperation可以调?start?法来执?任务,但默认是同步执行的
如果将NSOperation添加到NSOperationQueue(操作队列)中,系统会自动异步执行NSOperation中的操作
添加操作到NSOperationQueue中,自动执行操作,自动开启线程
1 //创建NSOperationQueue 2 NSOperationQueue * queue=[[NSOperationQueue alloc]init]; 3 //把操作添加到队列中 4 //第一种方式 5 [queue addOperation:operation1]; 6 [queue addOperation:operation2]; 7 [queue addOperation:operation3]; 8 //第二种方式 9 [queue addOperationWithBlock:^{10 NSLog(@"NSBlockOperation3--4----%@",[NSThread currentThread]);11 }];
- (void)addOperation:(NSOperation *)op;
- (void)addOperationWithBlock:(void (^)(void))block;
代码示例:
1 // 2 // YYViewController.m 3 // 03-NSOperation基本3 4 // 5 // Created by 孔医己 on 14-6-25. 6 // Copyright (c) 2014年 itcast. All rights reserved. 7 // 8 9 #import "YYViewController.h"10 11 @interface YYViewController ()12 13 @end14 15 @implementation YYViewController16 17 - (void)viewDidLoad18 {19 [super viewDidLoad];20 21 //创建NSInvocationOperation对象,封装操作22 NSInvocationOperation *operation1=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test1) object:nil];23 NSInvocationOperation *operation2=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test2) object:nil];24 //创建对象,封装操作25 NSBlockOperation *operation3=[NSBlockOperation blockOperationWithBlock:^{26 NSLog(@"NSBlockOperation3--1----%@",[NSThread currentThread]);27 }];28 [operation3 addExecutionBlock:^{29 NSLog(@"NSBlockOperation3--2----%@",[NSThread currentThread]);30 }];31 32 //创建NSOperationQueue33 NSOperationQueue * queue=[[NSOperationQueue alloc]init];34 //把操作添加到队列中35 [queue addOperation:operation1];36 [queue addOperation:operation2];37 [queue addOperation:operation3];38 }39 40 -(void)test141 {42 NSLog(@"NSInvocationOperation--test1--%@",[NSThread currentThread]);43 }44 45 -(void)test246 {47 NSLog(@"NSInvocationOperation--test2--%@",[NSThread currentThread]);48 }49 50 @end
打印效果:
注意:系统自动将NSOperationqueue中的NSOperation对象取出,将其封装的操作放到一条新的线程中执行。上面的代码示例中,一共有四个任务,operation1和operation2分别有一个任务,operation3有两个任务。一共四个任务,开启了四条线程。通过任务执行的时间全部都是273可以看出,这些任务是并行执行的。
下面使用for循环打印,可以更明显的看出任务是并发执行的。
代码示例:
1 #import "YYViewController.h" 2 3 @interface YYViewController () 4 5 @end 6 7 @implementation YYViewController 8 9 - (void)viewDidLoad10 {11 [super viewDidLoad];12 13 //创建NSInvocationOperation对象,封装操作14 NSInvocationOperation *operation1=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test1) object:nil];15 NSInvocationOperation *operation2=[[NSInvocationOperation alloc]initWithTarget:self selector:@selector(test2) object:nil];16 //创建对象,封装操作17 NSBlockOperation *operation3=[NSBlockOperation blockOperationWithBlock:^{18 for (int i=0; i<5; i++) {19 NSLog(@"NSBlockOperation3--1----%@",[NSThread currentThread]);20 }21 }];22 [operation3 addExecutionBlock:^{23 for (int i=0; i<5; i++) {24 NSLog(@"NSBlockOperation3--2----%@",[NSThread currentThread]);25 }26 }];27 28 //创建NSOperationQueue29 NSOperationQueue * queue=[[NSOperationQueue alloc]init];30 //把操作添加到队列中31 [queue addOperation:operation1];32 [queue addOperation:operation2];33 [queue addOperation:operation3];34 }35 36 -(void)test137 {38 for (int i=0; i<5; i++) {39 NSLog(@"NSInvocationOperation--test1--%@",[NSThread currentThread]);40 }41 }42 43 -(void)test244 {45 for (int i=0; i<5; i++) {46 NSLog(@"NSInvocationOperation--test2--%@",[NSThread currentThread]);47 }48 }49 50 @end