1.循环创建完5个按钮，然后在按钮的线面添加横线。
2.在按钮的点击事件中实现横线滑动的frame的改变
3.代码如下：
[UIView animateWithDuration:.35 animations:^{
CGFloat centerX = button.center.x;
CGPoint point = CGPointMake(centerX, _selectedLine.center.y);
_selectedLine.center = point;
[button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
} completion:^(BOOL finished) {
}];