通过view获取所在的viewController对象

建议写成UIView的分类，如下：

.h

- (UIViewController *)viewController;

.m

- (UIViewController *)viewController {
    UIResponder *responder = self.nextResponder;
    while (![responder isKindOfClass:[UIViewController class]] && responder != nil) {
        responder = responder.nextResponder;
    }
    return (UIViewController *)responder;
}