- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        //BOOL值默认为NO。    NSLog(@"---timeStart--%d-----",timeStart);        //发送验证码到手机上-Button    UIButton *sendYZM=[UIButton buttonWithType:UIButtonTypeCustom];    [sendYZM setFrame:CGRectMake(50, 100, 250, 50)];    [sendYZM setBackgroundColor:[UIColor redColor]];    [sendYZM setTitle:@"发送注册验证码到手机上" forState:UIControlStateNormal];    [sendYZM setTitleColor:[UIColor colorWithRed:66/255.0 green:66/255.0 blue:221/255.0 alpha:1.0] forState:UIControlStateNormal];    [sendYZM addTarget:self action:@selector(doClickButton:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:sendYZM];}-(void)doClickButton:(UIButton *)btn{    timeStart=YES;    sysTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerFireMethod:) userInfo:nil repeats:YES];    // 可以通过fire这个方法去触发timer，即使timer的firing time没有到达    [sysTimer fire];    [self getAuthCode];}//随时更新验证码发送的时间- (void)timerFireMethod:(NSTimer *)timer{    //定义一个NSCalendar对象    NSCalendar *cal = [NSCalendar currentCalendar];    //初始化目标时间...    NSDateComponents *endTime = [[NSDateComponents alloc] init];    //得到当前时间    NSDate *today = [NSDate date];    NSDate *date = [NSDate dateWithTimeInterval:60 sinceDate:today];    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];    NSString *dateString = [dateFormatter stringFromDate:date];        static int year;    static int month;    static int day;    static int hour;    static int minute;    static int second;        if(timeStart) {        //从NSDate中取出年月日，时分秒，但是只能取一次        year = [[dateString substringWithRange:NSMakeRange(0, 4)] intValue];        month = [[dateString substringWithRange:NSMakeRange(5, 2)] intValue];        day = [[dateString substringWithRange:NSMakeRange(8, 2)] intValue];        hour = [[dateString substringWithRange:NSMakeRange(11, 2)] intValue];        minute = [[dateString substringWithRange:NSMakeRange(14, 2)] intValue];        second = [[dateString substringWithRange:NSMakeRange(17, 2)] intValue];        timeStart = NO;    }        [endTime setYear:year];    [endTime setMonth:month];    [endTime setDay:day];    [endTime setHour:hour];    [endTime setMinute:minute];    [endTime setSecond:second];        //把目标时间装载入date    NSDate *todate = [cal dateFromComponents:endTime];        //用来得到具体的时差，是为了统一成北京时间    unsigned int unitFlags = NSYearCalendarUnit| NSMonthCalendarUnit| NSDayCalendarUnit| NSHourCalendarUnit| NSMinuteCalendarUnit| NSSecondCalendarUnit;        NSDateComponents *d = [cal components:unitFlags fromDate:today toDate:todate options:0];    NSLog(@"----%d---",[d second]);    if([d second] < 60 && [d second] > 0) {        NSString *miao = [NSString stringWithFormat:@"%d",[d second]];        NSLog(@"---miao----%@",miao);                UIButton *sendYZM=[UIButton buttonWithType:UIButtonTypeCustom];        [sendYZM setFrame:CGRectMake(50, 100, 250, 50)];        [sendYZM setBackgroundColor:[UIColor redColor]];        [sendYZM setTitle:[NSString stringWithFormat:@"重新发送验证码(%@秒)",miao] forState:UIControlStateNormal];        [sendYZM setTitleColor:[UIColor colorWithRed:66/255.0 green:66/255.0 blue:221/255.0 alpha:1.0] forState:UIControlStateNormal];        [self.view addSubview:sendYZM];           }else if([d second] == 0) {        [sysTimer invalidate];                UIButton *sendYZM=[UIButton buttonWithType:UIButtonTypeCustom];        [sendYZM setFrame:CGRectMake(50, 100, 250, 50)];        [sendYZM setBackgroundColor:[UIColor redColor]];        [sendYZM setTitle:@"重新发送验证码" forState:UIControlStateNormal];        [sendYZM setTitleColor:[UIColor colorWithRed:66/255.0 green:66/255.0 blue:221/255.0 alpha:1.0] forState:UIControlStateNormal];        [sendYZM addTarget:self action:@selector(doClickButton:) forControlEvents:UIControlEventTouchUpInside];        [self.view addSubview:sendYZM];    }}- (void)getAuthCode{    //将电话号码发送到服务器，服务器返回验证码。当验证码和注册用户输入一样的时候，则可以进行下一步操作。}