UIScrollView *scrollView = [UIScrollVie new];
[self.view addSubview:scrollView];
                            
UIView *containerView = [UIView new];
[scrollView addSubview:containerView];
                            
UIView *v1 = [UIView new];
v1.backgroundColor = [UIColor redColor];
[containerView addSubview:v1];
                            
UIView *v2 = [UIView new];
v2.backgroundColor = [UIColor blueColor];
[containerView addSubview:v2];
                
/*
如上，我想让v1、v2纵向排列，让scrollView可以上下滚动。
*/

// scrollView正常进行约束
[scrollView mas_makeConstraints:^(MASConstraintMaker *make) {
    make.edges.equalTo(self.view);
}];
                      
// 容器视图
[containerView mas_makeConstraints:^(MASConstraintMaker *make) {
    make.edges.width.equalTo(scrollView); // 试了发现这里好像必须要约束一下width
}];
                      
// v1、v2都放在容器里
[v1 mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.left.right.equalTo(containerView);
    make.height.equalTo(@400);
}];
[v2 mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.equalTo(v1.mas_bottom);
    make.left.right.equalTo(v1);
    make.height.equalTo(@400);
}];

// 这里需要补刀，来撑起contentSize
[containerView mas_makeConstraints:^(MASConstraintMaker *make) {
    make.bottom.equalTo(v2);
}];