线程锁

 1 #import "ViewController.h"
 2 
 3 @interface ViewController ()
 4 //总票数
 5 @property (nonatomic,assign) NSInteger count;
 6 @end
 7 
 8 @implementation ViewController
 9 
10 - (void)viewDidLoad {
11     [super viewDidLoad];
12     self.count = 100;
13     
14 }
15 - (IBAction)didClickSell:(id)sender {
16     
17     //线程锁
18     NSLock *lockObject = [[NSLock alloc] init];
19     for (int i = 0; i < 100;i++) {
20        //并行队列
21         dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
22             [lockObject lock];
23             NSLog(@"我买到了第%ld张票",(long)self.count);
24             self.count--;
25             [lockObject unlock];
26         });
27     }
28     
29 }