iOS 多线程的使用（Operation）

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#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

不能直接Operation是因为它里面没有直接操作的方法只是一个基类（抽象类）

NSInvocationOperation *invocation0 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(act:) object:@"invocation0"];

如果单独使用Operation必须手动启动

[invocation start];

Operation是在当前线程去执行（同步执行）

NSInvocationOperation *invocation1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(act:) object:@"invocation1"];

NSInvocationOperation *invocation2 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(act:) object:@"invocation2"];

NSInvocationOperation *invocation3 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(act:) object:@"invocation3"];

NSInvocationOperation *invocation4 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(act:) object:@"invocation4"];

NSBlockOperation *blockOperation = [NSBlockOperation blockOperationWithBlock:^{

具体执行的方法任务

[self act:@"blockOperation"];

}];

添加操作

NSBlockOperation的操作数大于1 的时候会开辟线程去执行

[blockOperation addExecutionBlock:^{

[self act:@"blockOperation2"];

}];

[blockOperation start];

operation默认在当期线程去执行（同步执行）

可以使用线程队列NSOperationQueue去管理线程 (默认会开辟线程去执行) 异步执行不用手动去启动线程

NSOperationQueue *queue = [[NSOperationQueue alloc]init];

可以线程队列的最大并发数（最多允许多少操作同时执行）

queue.maxConcurrentOperationCount = 3;

设置Operation的依赖关系

[invocation1 addDependency:invocation0];

[invocation2 addDependency:invocation1];

[invocation3 addDependency:invocation2];

[invocation4 addDependency:invocation3];

[blockOperation addDependency:invocation4];

[queue addOperation:invocation0];

[queue addOperation:invocation1];

[queue addOperation:invocation2];

[queue addOperation:invocation3];

[queue addOperation:invocation4];

[queue addOperation:blockOperation];

}

- (void)act:(id)sender

{

NSLog(@"%@%@",[NSThread currentThread],sender);

}

@end

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