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一、NSOperation简介
1.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
8 代码示例: 9 #import "YYViewController.h" 10 11 @interface YYViewController () 12 13 @end 14 15 @implementation YYViewController 16 17 - (void)viewDidLoad 18 { 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)test 33 { 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 }];
代码1:
9 #import "YYViewController.h" 10 11 @interface YYViewController () 12 13 @end 14 15 @implementation YYViewController 16 17 - (void)viewDidLoad 18 { 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:
9 #import "YYViewController.h" 10 11 @interface YYViewController () 12 13 @end 14 15 @implementation YYViewController 16 17 - (void)viewDidLoad 18 { 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
9 #import "YYViewController.h" 10 11 @interface YYViewController () 12 13 @end 14 15 @implementation YYViewController 16 17 - (void)viewDidLoad 18 { 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NSOperationQueue 33 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)test1 41 { 42 NSLog(@"NSInvocationOperation--test1--%@",[NSThread currentThread]); 43 } 44 45 -(void)test2 46 { 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:
9 - (void)viewDidLoad 10 { 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NSOperationQueue 29 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)test1 37 { 38 for (int i=0; i<5; i++) { 39 NSLog(@"NSInvocationOperation--test1--%@",[NSThread currentThread]); 40 } 41 } 42 43 -(void)test2 44 { 45 for (int i=0; i<5; i++) { 46 NSLog(@"NSInvocationOperation--test2--%@",[NSThread currentThread]); 47 } 48 } 49 50 @end
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原文地址:http://www.cnblogs.com/jiayongqiang/p/5097699.html