多线程

简介

iOS的多线程技术，包括

1. NSThread
2. NSOperation
3. GCD

NSThread

官方文档https://developer.apple.com/documentation/foundation/nsthread

//创建- (void)createThread{    for (int i=0; i<10; ++i) {        NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(doSomething:) object:[NSNumber numberWithInt:i]];        thread.name = [NSString stringWithFormat:@"myThread%i",i];//设置线程名称        thread.threadPriority = 1.0;//优先级，从0-1        [thread start];    }}还有其他方法//取消线程- (void)cancel;//启动线程- (void)start;//判断某个线程的状态的属性@property (readonly, getter=isExecuting) BOOL executing;@property (readonly, getter=isFinished) BOOL finished;@property (readonly, getter=isCancelled) BOOL cancelled;//设置和获取线程名字-(void)setName:(NSString *)n;-(NSString *)name;//获取当前线程信息+ (NSThread *)currentThread;//获取主线程信息+ (NSThread *)mainThread;//使当前线程暂停一段时间，或者暂停到某个时刻+ (void)sleepForTimeInterval:(NSTimeInterval)time;+ (void)sleepUntilDate:(NSDate *)date;

NSOperation

NSOperation是对GCD的包装，包含NSOperationQueue和NSOperation两个基本要素。
官方文档https://developer.apple.com/documentation/foundation/nsoperation

由于NSOperation是一个抽象类，所以使用的时候，要自己创建其子类，或者直接使用NSInvocationOperation、NSBlockOperation。

使用

• NSInvocationOperation

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

• NSBlockOperation

NSBlockOperation *blockOP = [NSBlockOperation blockOperationWithBlock:^{}];[blockOP start];

• 创建子类