登陆注册密码错误或者输入为空时震动效果

 CAKeyframeAnimation *keyFrame = [CAKeyframeAnimation animationWithKeyPath:@"position.x"];
    keyFrame.duration = 0.3;
    CGFloat x = self.layer.position.x;
    keyFrame.values = @[@(x - 30), @(x - 30), @(x + 20), @(x - 20), @(x + 10), @(x - 10), @(x + 5), @(x - 5)];
    [self.layer addAnimation:keyFrame forKey:@"shake"];