特拉弗斯UIView.subviews獲得按鈕迅速

Question

在我的Objective-C代碼，我可以用這個方法查找view.subviews的button：

-(UIButton*)findButtonInView: (UIView*)v { 
    for (UIView *subView in v.subviews) { 
     if ([subView isKindOfClass:[UIButton class]]) { 
      return (UIButton*)subView; 
     } 
     else if ([subView isKindOfClass:[UIView class]]) { 
      UIButton* btn = [self findButtonInView:subView]; 
      if(btn) { 
       return btn; 
      } 
     } 
    } 
    return nil; 
} 

UIButton* searchButton = [self findButtonInView:self.searchBar]; 

但我怎麼能做出一個方法來找到button在view作者Swift？

正如你所知道的這個斯威夫特方法，我不能像回到nil：

class func findButtonInView(_ view:UIView) -> UIButton {} 

Answer 1

class func findButtonInView(_ view:UIView) -> UIButton?{}