iOS&Swift自定义的tabbar出现重叠

（使用popToViewController导致的UITabBarButton重叠的问题）

在iOS8 中允许动态添加tabbaritem，自定义的tabbar会出现重叠的情况，原本viewDidLoad()中已经移除的UITabBarButton再次出现。

解决：在自定义的BaseViewController的viewWillLayoutSubViews()方法里去移除UITabBarButton

// MARK: - Swift移除UITabBarButton
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        //print("viewWillLayoutSubviews：\(self.tabBarController?.tabBar.subviews)")
        let aClass:AnyClass = NSClassFromString("UITabBarButton")!
        guard let views = self.tabBarController?.tabBar.subviews else { return }
        for view in views {
            if view.isKind(of: aClass) {
                view.removeFromSuperview()
            }
        }
    }

#pragma mark - OC移除UITabBarButton
- (void)viewWillLayoutSubviews {
    [super viewWillLayoutSubviews];
    // tabBar移除UITabBarButton
    for (UIView *subView in self.tabBar.subviews) {
        if ([subView isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
            [subView removeFromSuperview];
        }
    }
}