Objective-C 笔记 – 多线程

互斥锁


@property(nonatomic, assign) init tickets;

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    self.tickets = 20;

    NSThread * t1 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTickets) object:nil];
    [t1 start];

    NSThread * t2 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTickets) object:nil];
    [t2 start];
}

- (void)saleTickets {
    while(YES) {
        [NSThread sleepForTimeInterval: 1.0];
        // 互斥锁可以让锁内代码同一时间只被一条线程运行
        @synchronized(self) {
            if(self.tickets > 0) {
                self.tickets--;
                NSLog(@"剩下%d张票", self.tickets);
            } else {
                NSLog(@"卖完了");
                break;
            }
        }
    }
}

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