iOS中多线程的总结
@synchronized（锁对象）{//需要锁定的代码}
线程间的通讯
[selfperformSelectorOnMainThread:@selector(<#selector#>) withObject:<#(nullable id)#> waitUntilDone:<#(BOOL)#>];
[selfperformSelector:<#(nonnull SEL)#> onThread:<#(nonnull NSThread *)#> withObject:<#(nullable id)#> waitUntilDone:<#(BOOL)#>]
串行队列
dispatch_queue_tqueue =dispatch_queue_create("wangjianye",NULL)
dispatch_queue_tqueue =dispatch_get_main_queue() 主队列
并发队列
dispatch_queue_tqueue =dispatch_get_global_queue(DISPATCH_TARGET_QUEUE_DEFAULT,0 )
同步函数
dispatch_sync(queue, ^{
})
异步函数
dispatch_async(queue, ^{
})
队列组
dispatch_group_tgroup =dispatch_group_create();
dispatch_group_async(group,queue, ^{
})
dispatch_group_async(group,queue, ^{
})
dispatch_group_notify(group, main_queue, ^{
})
NSOperation和NSOperationQueue实现多线程的具体步骤
（1）先将执行的操作封装到NSOperation对象中
（2）然后将NSOperation对象添加到NSOperationQueue中
（3）系统会自动将NSOperation封装的操作放到一个新的线程中执行
NSOperation是个抽象类,并不具备封装操作的能力,必须使⽤它的子类
使用NSOperation⼦类的方式有3种：
（1）NSInvocationOperation
（2）NSBlockOperation
（3）自定义子类继承NSOperation,实现内部相应的⽅法
NSInvocationOperation的用法：
NSInvocationOperation*operation = [[NSInvocationOperationalloc]initWithTarget:selfselector:@selector(run)object:nil];
[operationstart];
NSBlockOperation的用法：
NSBlockOperation*operation = [NSBlockOperationblockOperationWithBlock:^{
}];
添加执行， 加不加都可以：
[operationaddExecutionBlock:^{
}];
[operationaddExecutionBlock:^{
}];
[operationstart];
NSOperationQueue的用法：
NSOperationQueue*queue = [[NSOperationQueuealloc]init];
[queue addOperation:operation0];
[queue addOperation:operation1];
[queue addOperation:operation2];
[queueaddOperationWithBlock:^{
}];
队列的取消操作：
[queuecancelAllOperations]
暂停与恢复队列:
[queuesetSuspended:YES]
设置NSOperation 在queue的优先级
[operationsetQueuePriority:NSOperationQueuePriorityNormal]
设置 NSOperation 的依赖
[operationaddDependency:operation1]
设置NSOperation 的完成
[operationsetCompletionBlock:^{
}];
自定义NSOperation的子类
