iOS设置UINavigationController背景颜色

在iOS15系统及以上设置导航栏背景颜色

UINavigationBarAppearance *navigationBarAppearance = [[UINavigationBarAppearance alloc] init];
navigationBarAppearance.backgroundColor = [UIColor blueColor]; 
navigationBarAppearance.titleTextAttributes = @{
    NSForegroundColorAttributeName : [UIColor whiteColor],
    NSFontAttributeName : [UIFont systemFontOfSize:15]
};
self.navigationController.navigationBar.standardAppearance = navigationBarAppearance;
self.navigationController.navigationBar.scrollEdgeAppearance = navigationBarAppearance;