解决iOS TabBar图标不支持暗黑模式的问题

最近着手适配iOS暗黑模式，发现TabBar图标比较奇特，居然不支持Dark模式的图片

经过一番折腾，找到了解决方法

- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection{
    
    [super traitCollectionDidChange:previousTraitCollection];

    if (@available(iOS 12.0, *)) {
        
        TCMNavigationController *navigationController = self.childViewControllers[2];
        
        UIImage *newImage = nil;
        
        if (previousTraitCollection.userInterfaceStyle == UIUserInterfaceStyleDark) {
            newImage = [UIImage imageNamed:@"icon_tab_normal"];
        }else{
            newImage = [UIImage imageNamed:@"icon_tab_dark"];
        }
        
        navigationController.tabBarItem.image = [newImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    }
}

注意，设置图片时务必使用一下方法：

[newImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal]

希望对你有所帮助~