从UINavigationController中移除多个UIVi

环境：分别有ViewControllerA、ViewControllerB、ViewControllerC、ViewControllerD。
要实现的跳转顺序：ViewControllerA -> ViewControllerB -> ViewControllerC -> ViewControllerD，ViewControllerD直接跳回ViewControllerA。

在ViewControllerD中调用下面的方法。
可将该方法放到UIViewController的分类中，需要时直接调用：

/// 从导航栈中移除fromViewControllerClasses 到[self class]之间的VC
- (void)removeViewControllerFromNavigationStackWithStartControllerClasses:(NSArray *)startClasses {
    for (int i = 0; i < startClasses.count; i++) {
        Class startClass = startClasses[i];
        BOOL flag;
        flag = [self canRemoveViewControllerFromNavigationStackFrom:startClass to:[self class]];
        if (flag) {
            break;
        }
    }
}

/// 从导航栈中移除fromViewControllerClass 到 toViewControllerClass之间的VC
- (BOOL)canRemoveViewControllerFromNavigationStackFrom:(Class)fromClass
                                                    to:(Class)toClass {
    NSMutableArray *viewControllers = [[NSMutableArray alloc] initWithArray:self.navigationController.viewControllers];
    // 将要删除的VC放到该数组中
    NSMutableArray *removedVCs = [NSMutableArray array];
    
    NSInteger fromIndex = -1;
    NSInteger toIndex = -1;
    /// 是否发现起始VC
    BOOL flag = NO;
    
    for (int i = 0; i < viewControllers.count; i++) {
        UIViewController *vc = viewControllers[i];
        if ([vc isKindOfClass:fromClass]) {
            fromIndex = i;
            flag = YES;
        } else if ([vc isKindOfClass:toClass]) {
            toIndex = i;
        }
        
        // 如果已发现起始VC，并且viewController不为要删除的VC时，记录到要删除的数组中
        if (flag == YES &&
            i != fromIndex &&
            i != toIndex) {
            [removedVCs addObject:vc];
        }
    }
    
    if (flag == NO) {
        return NO;
    }
    
    for (UIViewController *vc in removedVCs) {
        [viewControllers removeObject:vc];
    }
    
    self.navigationController.viewControllers = viewControllers;
    return YES;
}