UITabBarの背景を削除する
-(void)removeTabBarBackground:(UITabBar*)_tab{
    for(UIView*t in _tab.subviews){
        NSString*s=NSStringFromClass([t class]);
        if ([s isEqualToString:@"UITabBarButton"] || t==_tab) {
            continue;
        }
        [t removeFromSuperview];
        break;
    }
}

[self removeTabBarBackground:_mytab];