贴个现成的吧。源代码在 Masonry 中，查看 View+MASAdditions.h/m 文件即可。

这是个实例方法，类方法也一样；只是 self 变成 view1 罢了。

遍历 self 的 superview ，去匹配 view 。
然后取 view 得 superview ，再遍历一遍 self 的 superview 。循环不到，也就返回 nil 了。
记得回复不能 markdown 的样子，就直接复制下代码，不会太好看。

- (instancetype)mas_closestCommonSuperview:(MAS_VIEW *)view {
MAS_VIEW *closestCommonSuperview = nil;

MAS_VIEW *secondViewSuperview = view;
while (!closestCommonSuperview && secondViewSuperview) {
MAS_VIEW *firstViewSuperview = self;
while (!closestCommonSuperview && firstViewSuperview) {
if (secondViewSuperview == firstViewSuperview) {
closestCommonSuperview = secondViewSuperview;
}
firstViewSuperview = firstViewSuperview.superview;
}
secondViewSuperview = secondViewSuperview.superview;
}
return closestCommonSuperview;
}