用NSThread,如何启动,阻塞,关闭线程

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    //创建线程
    NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(run2) object:nil];
    //启动线程
    [thread start];
}

-(void)run2
{
    for (NSInteger i=0; i<100; i++) {
        NSLog(@"%@--%zd",[NSThread currentThread],i);
        if (50 == i) {
            //死亡
//            [NSThread exit];
//            return;
            
            break;
        }
    }
}
-(void)run
{
    NSLog(@"-----");
    //阻塞线程
//    [NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:2.0]];
    
    [NSThread sleepForTimeInterval:3.0];
//    NSLog(@"%@",[NSDate distantFuture]);
    
//    [NSThread sleepForTimeInterval:3.0];
//    [NSThread sleepUntilDate:[NSDate distantFuture]];
//    [NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:3.0]];
    NSLog(@"+++++++");
}