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来源：互联网发布：js yui在线压缩编辑：程序博客网时间：2024/06/16 09:15

import “ViewController.h”

@interface ViewController ()
{
UILabel *showTicket;
int curtTicketNum; //当前票数
int saleTicketNum; // 销售票数

NSString *windowName; //窗口名字NSCondition *condition;//线程锁

}

@end

@implementation ViewController

(void)viewDidLoad {
[super viewDidLoad];
curtTicketNum = 100;
self.view.backgroundColor = [UIColor brownColor];

// 卖票系统分三个窗口同时销售

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];button.frame = CGRectMake(100, 100, 100, 50);[button setTitle:@"开始卖票" forState:UIControlStateNormal];[button addTarget:self action:@selector(startSale) forControlEvents:UIControlEventTouchUpInside];[self.view addSubview:button];showTicket = [[UILabel alloc]init];showTicket.frame = CGRectMake(200, 100, 100, 500);showTicket.text = @"余票:100张";showTicket.textAlignment = NSTextAlignmentCenter;showTicket.numberOfLines = 5;showTicket.textColor = [UIColor redColor];[self.view addSubview:showTicket];

}

//三个窗口同时卖票
-(void)startSale
{
//初始化三个线程每一个线程都是一个售票窗口
NSThread *window1 = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];
window1.name = @”售票窗口1”;
[window1 start];

NSThread *window2 = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];window2.name = @"售票窗口2"; [window2 start];NSThread *window3 = [[NSThread alloc]initWithTarget:self selector:@selector(saleTicket) object:nil];window3.name = @"售票窗口3"; [window3 start];

// 线程锁 NSCondition 是一个线程锁（条件锁）
condition = [[NSCondition alloc]init];

}

-(void)saleTicket
{

// 没有使用线程锁三个线程（窗口）会同时访问这个方法（卖票的方法）所以当剩余票数是0的时候有可能其他两个线程不知道剩余票数是0 还会同时访问，此事剩余票数会出现负数的情况

// 解决这个问题可以使用线程锁
// 只允许一个线程访问完毕之后，另外一个线程再去访问
// 使用线程锁值允许一个线程去访问

while (curtTicketNum>0) {     [condition lock];//锁住    [NSThread sleepForTimeInterval:0.1];

// 当前票数(剩余)
curtTicketNum -=1;
// 卖的票数
saleTicketNum = 100-curtTicketNum;
windowName = [NSThread currentThread].name;
if (curtTicketNum>0) {
[condition unlock]; //当一个窗口卖完票后在解锁
}

    [self performSelectorOnMainThread:@selector(upDataUI) withObject:nil waitUntilDone:YES];}curtTicketNum = 100;

}

//更新界面
-(void)upDataUI
{
showTicket.text = [NSString stringWithFormat:@”已经销售%d 还剩%d 当前窗口是%@”,saleTicketNum,curtTicketNum,windowName];

}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

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