修改tabBarItem  默認圖片和選中時的圖片

UITabBarItem* item1 = [self.tabBar.items objectAtIndex:0];
    item1.image = [[UIImage imageNamed:@"icon_video"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    item1.selectedImage = [[UIImage imageNamed:@"icon_video_on"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];