IOS多线程加锁

注意：加锁位置不同产生结果不同

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    //设置中票数

    self.totalCount = ;

     self.threadA = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];

     self.threadB = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];

     self.threadC = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];

    self.threadA.name = @"售票员A";

    self.threadB.name = @"售票员B";

    self.threadC.name = @"售票员C";

    //启动线程

        [self.threadA start];

        [self.threadB start];

        [self.threadC start];

}

-(void)saleTicket

{

    while () {

    //锁:必须是全局唯一的

    //1.注意枷锁的位置

    //2.注意枷锁的前提条件,多线程共享同一块资源

    //3.注意加锁是需要代价的,需要耗费性能的

    //4.加锁的结果:线程同步

    @synchronized(self) {

        //线程1

        //线程2

        //线程3

        NSInteger count = self.totalCount;

        if (count >) {

            for (NSInteger i = ; i<; i++) {

            }

            self.totalCount = count - ;

            //卖出去一张票

            NSLog(@"%@卖出去了一张票,还剩下%zd张票", [NSThread currentThread].name,self.totalCount);

        }else

        {

            NSLog(@"不要回公司上班了");

            break;

        }

        }

    }

}