一、当返回上一个界面时，需要返回之前的某一个视图

    //获取总的VC的数组
    UINavigationController *nc = self.navigationController;
    NSMutableArray *mArray = [NSMutableArray arrayWithArray:nc.viewControllers];
    NSInteger count = mArray.count;
    
    //获取上一个视图
    BaseController *topVC = mArray[count - 2];
    if ([topVC isKindOfClass:[OrderSettlementViewController class]]) {
        [mArray removeObject:topVC];
    }
    self.navigationController.viewControllers = mArray;