scrollView使用masonry

//使用 [self.view addSubview:scrollV];
//不能用self.view = scrollV;

[scrollV mas_makeConstraints:^(MASConstraintMaker* make) {
make.edges.mas_equalTo(self.view);
//contentSize 随着内容增多而增多
make.bottom.mas_equalTo(commitBtn.mas_bottom).offset(8);
}];
}