IOS中的多线程【二】— NSOperation和NSOperationQueue

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

//1.定义4个队列

NSBlockOperation
* operation1 = [NSBlockOperation
blockOperationWithBlock:^

                                {

                                    NSLog(@"1.下载图片");

                                }];

NSBlockOperation
* operation2 = [NSBlockOperation
blockOperationWithBlock:^

                                 {

                                     NSLog(@"2.修饰图片");

                                 }];

NSBlockOperation
* operation3 = [NSBlockOperation
blockOperationWithBlock:^

                                 {

                                     NSLog(@"3.保存图片");

                                 }];

NSBlockOperation
* operation4 = [NSBlockOperation
blockOperationWithBlock:^

                                 {

                                     NSLog(@"4.显示图片");

                                 }];

//2.设置依赖关系，保证顺序执行。

[operation2 addDependency:operation1];

[operation3 addDependency:operation2];

[operation4 addDependency:operation3];

//3.将任务添加到队列中去，并开始执行。

[self.queue addOperation:operation1];

[self.queue addOperation:operation2];

[self.queue addOperation:operation3];

//更新UI操作在主队列中执行，依赖关系是可以跨队列的。

[[NSOperationQueue
mainQueue] addOperation:operation4];