@interface BTThreadViewController (){    NSThread *OneThread;//师傅一    NSThread *TwoThread;//师傅二    NSThread *ThreeThread;//师傅三    int allCake;//蛋糕总数}@end@implementation BTThreadViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];        [self myThread];}-(void)myThread{    allCake = 10;        //给每个线程起一个名字，方便下面区分    OneThread = [[NSThread alloc] initWithTarget:self selector:@selector(SendTheCake) object:nil];    OneThread.name = @"师傅一";    [OneThread start];        TwoThread = [[NSThread alloc] initWithTarget:self selector:@selector(SendTheCake) object:nil];    TwoThread.name = @"师傅二";    [TwoThread start];        ThreeThread = [[NSThread alloc] initWithTarget:self selector:@selector(SendTheCake) object:nil];    ThreeThread.name = @"师傅三";    [ThreeThread start];}-(void)SendTheCake{    while (1) {        //线程锁的优点：能有效防止因多线程抢夺资源造成的数据安全问题,缺点：需要消耗大量的CPU资源,线程锁的使用前提：多条线程抢夺同一块资源,相关专业术语：线程同步,多条线程按顺序地执行任务。线程锁，就是使用了线程同步技术        @synchronized(self){            if (allCake > 0) {                                //线程休眠时间                [NSThread sleepForTimeInterval:0.002];                                //蛋糕个数－1                allCake -= 1;                //打印当前的线程和剩余蛋糕数量                NSThread *senderThread = [NSThread currentThread];                NSLog(@"--%@发了1个蛋糕，还剩下%d个蛋糕",senderThread,allCake);            }            else            {                //退出线程                [NSThread exit];            }        }    }}