棧管理總結
1、基本的入/出棧

// 進
[self.navigationController pushViewController:resCtr animated:YES];
// 出
[self.navigationController popViewControllerAnimated:YES];

2、查找棧（查）

NSMutableArray *marr = [[NSMutableArray alloc]initWithArray:self.navigationController.viewControllers];
for (UIViewController *vc in marr) {
    if ([vc isKindOfClass:NSClassFromString(@"WantClass")]) {
        NSLog(@"找到了")
        break;
    }
}

3、進入/返回到指定棧

// 進
[self.navigationController popToViewController:Ctr animated:YES];
// 出
NSMutableArray *marr = [[NSMutableArray alloc]initWithArray:self.navigationController.viewControllers];
for (UIViewController *vc in marr) {
    if ([vc isKindOfClass:NSClassFromString(@"WantClass")]) {
        [self.navigationController popToViewController:vc animated:YES];
        break;
    }
}

4、在指定位置插入指定棧（增）

NSMutableArray *viewControllers = [self.navigationController.viewControllers mutableCopy];
for (int i = 0; i < viewControllers.count; i++){
    id vc = viewControllers[i];
    if ([vc isKindOfClass:[GCWKWebViewController class]]){
       UIViewController *insertVC = [[NSClassFromString(@"WantClass") alloc] init];
       [viewControllers insertObject:insertVC atIndex:i + 1];
       [self.navigationController setViewControllers:viewControllers animated:NO];
       // [self.navigationController popToViewController:insertVC animated:YES];
        break;;
     }
}

5、刪除指定棧（刪）

 NSMutableArray *viewControllers = [[NSMutableArray alloc]initWithArray:self.navigationController.viewControllers];
 for (UIViewController *vc in viewControllers) {
    if ([vc isKindOfClass:NSClassFromString(@"WantClass")]) {
       [viewControllers removeObject:vc];
       break;
      }
 }
 self.navigationController.viewControllers = viewControllers;

6、更改指定棧（改）

 NSMutableArray *viewControllers = [[NSMutableArray alloc]initWithArray:self.navigationController.viewControllers];
 for (UIViewController *vc in viewControllers) {
    if ([vc isKindOfClass:NSClassFromString(@"WantClass")]) {
       UIViewController *replaceVC = [[NSClassFromString(@"WantClass") alloc] init];
       [viewControllers replaceObjectAtIndex:i withObject:replaceVC];
       break;
      }
 }
 self.navigationController.viewControllers = viewControllers;