@synchronized 的作用是创建一个互斥锁,保证此时没有其它线程对self对象进行修改。这个是objective-c的一个锁定令牌,防止self对象在同一时间内被其它线程访问,起到线程的保护作用。
#import "ViewController.h"
@interface ViewController ()
/** 售票员01 */
@property (nonatomic, strong) NSThread *thread01;
/** 售票员02 */
@property (nonatomic, strong) NSThread *thread02;
/** 售票员03 */
@property (nonatomic, strong) NSThread *thread03;
/** 票的总数 */
@property (nonatomic, assign) NSInteger ticketCount;
/** 锁对象 */
//@property (nonatomic, strong) NSObject *locker;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// self.locker = [[NSObject alloc] init];
self.ticketCount = 100;
self.thread01 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTicket) object:nil];
self.thread01.name = @"售票员01";
self.thread02 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTicket) object:nil];
self.thread02.name = @"售票员02";
self.thread03 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTicket) object:nil];
self.thread03.name = @"售票员03";
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.thread01 start];
[self.thread02 start];
[self.thread03 start];
}
- (void)saleTicket
{
while (1) {
@synchronized(self) {
// 先取出总数
NSInteger count = self.ticketCount;
if (count > 0) {
self.ticketCount = count - 1;
NSLog(@"%@卖了一张票,还剩下%zd张", [NSThread currentThread].name, self.ticketCount);
} else {
NSLog(@"票已经卖完了");
break;
}
}
}
}
@end