1.继承UITabBarController

@interface ALTabBarController : UITabBarController

2.重写UITabBarController的UITabBarController方法

- (void)viewWillLayoutSubviews{
    CGRect tabFrame = self.tabBar.frame; //self.TabBar is IBOutlet of your TabBar
    tabFrame.size.height = 80;
    tabFrame.origin.y = self.view.frame.size.height - 80;
    self.tabBar.frame = tabFrame;
}

如果想要添加的工具条点击事件生效请在viewWillLayoutSubviews添加此代码

[self.tabBar bringSubviewToFront:self.bottomToolView];

3.效果图

UITabBar改变默认高度

4.参考

http://stackoverflow.com/questions/23044218/change-uitabbar-height