[self.view addSubview:self.topScrollView];

UIImageView *lastIv = nil;
CGFloat ivW = 68 * kScaleFactor;
CGFloat ivH = 68 * kScaleFactor;
CGFloat padding = (kScreenW - 26 * kScaleFactor - ivW * 4) / 3;
for (int i = 0; i < 6; i++) {
    UIImageView *iv = [[UIImageView alloc] init];
    iv.backgroundColor = [UIColor redColor];
    [self.topScrollView addSubview:iv];
    [iv mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.topScrollView).offset(35 * kScaleFactor);
        make.size.mas_equalTo(CGSizeMake(ivW, ivH));
        if (lastIv) {
            make.left.equalTo(lastIv.mas_right).offset(padding);
        } else {
            make.left.equalTo(self.topScrollView.mas_left).offset(13 * kScaleFactor);
        }
    }];
    lastIv = iv;
}

[self.topScrollView mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.left.equalTo(self.view);
    make.height.mas_equalTo(@(139 * kScaleFactor));
    make.right.mas_equalTo(lastIv.mas_right).offset(13 * kScaleFactor);
}];

现在遇到的情况如下：
topScrollView 为scrollView，将创建的scrollView添加到控制器的View中，注意是直接添加。
添加完毕之后，发现一个问题就是scrollView不能滚动。

采用了如下解决方案：

首先添加一个和scrollView一样大小的UIView.

UIView *bgView = [[UIView alloc] init];
    [self.view addSubview:bgView];
    [bgView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.right.top.equalTo(self.view);
        make.height.mas_equalTo(@(139 * kScaleFactor));
    }];

最后添加topScrollView的约束为：

 [self.topScrollView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.edges.equalTo(bgView);
        make.right.mas_equalTo(lastIv.mas_right).offset(13 * kScaleFactor);
    }];