改变tabbar的高度做法

 UITabBarController *tabBarController =[[UITabBarController alloc] init];
     CGRect frame = self.window.bounds;
     tabBarController.tabBar.frame = CGRectMake(, CGRectGetHeight(frame) - , CGRectGetWidth(frame), CGRectGetHeight(frame));
     UIView *transitionView = [[tabBarController.view subviews] objectAtIndex:];
     frame.size.height = CGRectGetHeight(frame) - ;
     transitionView.frame = frame;