多线程（三）

本来想写在上个多线程(二)呢，无奈GCD内容太多，暂时先写那么多

NSOperation

NSOperation 是对GCD的封装，面向对象NSOperation-> {GCD},NSOperationQueue-> dispatch_queue ，由于NSOperation是抽象类，其实现的两种方式： Selector 和 block 执行任务分别对应 NSInvocationOperation 和 NSBlockOperation

直接上代码：

Selector 方式

NSInvocationOperation * invocation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(methodTest) object:nil];[invocation start];NSInvocationOperation * invocation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(methodTest) object:nil];[invocation start];

block 方式

NSBlockOperation * operation = [NSBlockOperation blockOperationWithBlock:^{     NSLog(@"线程%@",[NSThread currentThread]);}];//多个block 之间会并发执行，在在主线程和其它的多个线程for (int i = 0; i < 5; i++) {    [operation addExecutionBlock:^{        NSLog(@"线程%@",[NSThread currentThread]);    }];}[operation start];/** 2017-11-07 18:19:44.899 多线程测试[12298:367880] 线程<NSThread: 0x60800007bc80>{number = 5, name = (null)} 2017-11-07 18:19:44.899 多线程测试[12298:367883] 线程<NSThread: 0x600000078440>{number = 4, name = (null)} 2017-11-07 18:19:44.899 多线程测试[12298:367881] 线程<NSThread: 0x60800007bc40>{number = 3, name = (null)} 2017-11-07 18:19:44.900 多线程测试[12298:367883] 线程<NSThread: 0x600000078440>{number = 4, name = (null)} 2017-11-07 18:19:44.900 多线程测试[12298:367880] 线程<NSThread: 0x60800007bc80>{number = 5, name = (null)} 2017-11-07 18:19:44.899 多线程测试[12298:367781] 线程<NSThread: 0x60800006e7c0>{number = 1, name = main} */

队列(自动start)
主队列

NSOperationQueue * queue = [NSOperationQueue mainQueue];

其它队列,全部子线程

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

测试

NSBlockOperation * operation = [NSBlockOperation blockOperationWithBlock:^{    NSLog(@"线程%@",[NSThread currentThread]);}];for (int i = 0; i < 5; i++) {    [operation addExecutionBlock:^{        NSLog(@"线程%@",[NSThread currentThread]);    }];}//[queue setMaxConcurrentOperationCount:1];//设置最大并发数,类似于串行[queue addOperation:operation];/** 2017-11-07 18:24:55.277 多线程测试[12356:370699] 线程<NSThread: 0x608000268700>{number = 6, name = (null)} 2017-11-07 18:24:55.277 多线程测试[12356:370685] 线程<NSThread: 0x600000263200>{number = 4, name = (null)} 2017-11-07 18:24:55.277 多线程测试[12356:370682] 线程<NSThread: 0x6080002685c0>{number = 3, name = (null)} 2017-11-07 18:24:55.277 多线程测试[12356:370683] 线程<NSThread: 0x600000263800>{number = 5, name = (null)} 2017-11-07 18:24:55.278 多线程测试[12356:370699] 线程<NSThread: 0x608000268700>{number = 6, name = (null)} 2017-11-07 18:24:55.278 多线程测试[12356:370685] 线程<NSThread: 0x600000263200>{number = 4, name = (null)} */

设置依赖

NSBlockOperation * block1 = [NSBlockOperation blockOperationWithBlock:^{     NSLog(@"线程1 - %@", [NSThread currentThread]);}];NSBlockOperation * block2 = [NSBlockOperation blockOperationWithBlock:^{    NSLog(@"线程2 - %@", [NSThread currentThread]);}];NSBlockOperation * block3 = [NSBlockOperation blockOperationWithBlock:^{    NSLog(@"线程3 - %@", [NSThread currentThread]);}];//Block3，block1,block2[block1 addDependency:block3];[block2 addDependency:block1];NSOperationQueue * queue = [[NSOperationQueue alloc]init];/*    [block3 removeDependency:block1]; */ //解除依赖[queue addOperations:@[block1,block2,block3] waitUntilFinished:YES];NSLog(@"%@,测试",[NSThread currentThread]); //决定于上局代码是否为YES/** 2017-11-07 18:41:16.621 多线程测试[12510:379366] 线程3 - <NSThread: 0x608000262ac0>{number = 3, name = (null)} 2017-11-07 18:41:16.621 多线程测试[12510:379355] 线程1 - <NSThread: 0x600000266f00>{number = 4, name = (null)} 2017-11-07 18:41:16.622 多线程测试[12510:379355] 线程2 - <NSThread: 0x600000266f00>{number = 4, name = (null)} */

总结：
1、最大特色就是可以设置依赖和最大并发数
2、可以通过waitUntilFinish 阻塞线程
3、封装了GCD,使用起来简单