有两种方法：

1.给UIView添加一个Category

- (UIView *) getFirstResponder
{
    if (self.isFirstResponder) {
        return self;
    }
    
    for (UIView *subView in self.subviews) {
        UIView *firstResponder = [subView getFirstResponder];
        if (firstResponder != nil) {
            return firstResponder;
        }
    }
    
    return nil;
}

2.给UIResponder添加一个Category(来源)

static __weak id currentFirstResponder;

+(id)currentFirstResponder {
    currentFirstResponder = nil;
    [[UIApplication sharedApplication] sendAction:@selector(findFirstResponder:) to:nil from:nil forEvent:nil];
    return currentFirstResponder;
}

-(void)findFirstResponder:(id)sender {
    currentFirstResponder = self;
}