短信按钮定时器

{

timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(Timing) userInfo:nil repeats:YES];

    num = 60;

    [timer fire];

}

- (void)Timing{

    num--;

    [timeBtn setTitle:[NSString stringWithFormat:@"%d",num] forState:UIControlStateNormal];

    if (num == 0) {

        [timer invalidate];

        timer = nil;

        [timeBtn setTitle:@"重新发送" forState:UIControlStateNormal];

        [forgetView.loginVerificationCodeBtn setEnabled:YES];

    }else{

        [forgetView.loginVerificationCodeBtn setEnabled:NO];

    }

}