一、實現(xiàn)原理：
通過消息響應(yīng)者鏈找到UIView所在的UIViewController

• UIView類繼承于UIResponder,通過UIResponder的next方法來獲取UIViewController.
• 如果next返回是空，則繼續(xù)向上遍歷superview并再次使用next方法獲取。這樣一直找下去，直到找到或拋出異常。

二、實現(xiàn)代碼

• 通過擴(kuò)展UIView,給其添加個viewController方法，從而讓我們可以獲得任意視圖對象（View）所屬視圖控制器

Swift

func viewController() -> UIViewController? {
    for view in sequence(first: self.superview, next: { $0?.superview }) {
        if let responder = view?.next {
            if responder.isKind(of: UIViewController.self){
                return responder as? UIViewController                   
            }
        }
    }
    return nil
}

Objective-C

-(UIViewController *)viewController{
    UIViewController *viewController = nil;
    UIResponder *next = self.nextResponder;
    while (next) {
        if ([next isKindOfClass:[UIViewController class]]) {
            viewController = (UIViewController *)next;
            break;
        }
        next = next.nextResponder;
    }
    return viewController;
}