获取当前的第一个响应者，而不使用私有API [英] Get the current first responder without using a private API

问题描述

我在一个多星期前提交了我的应用程式，今天收到了可怕的拒绝电子邮件。它告诉我，我的应用程序不能被接受，因为我使用非公共API;具体来说，

I submitted my app a little over a week ago and got the dreaded rejection email today. It tells me that my app cannot be accepted because I'm using a non-public API; specifically, it says,

应用程序中包含的非公共API是firstResponder。

The non-public API that is included in your application is firstResponder.

现在，冒犯的API调用实际上是我在SO上找到的解决方案：

Now, the offending API call is actually a solution I found here on SO:

UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView   *firstResponder = [keyWindow performSelector:@selector(firstResponder)];

如何在屏幕上获取当前的第一个响应者？

How do I get the current first responder on the screen? I'm looking for a way that won't get my app rejected.

推荐答案

在我的一个应用程序中，我经常想要的是第一响应者如果用户在背景上轻敲则辞职。为此，我在UIView上写了一个类别，我在UIWindow上调用。

In one of my applications I often want the first responder to resign if the user taps on the background. For this purpose I wrote a category on UIView, which I call on the UIWindow.

下面是基于这个，应该返回第一个响应者。

The following is based on that and should return the first responder.

@implementation UIView (FindFirstResponder)
- (id)findFirstResponder
{
    if (self.isFirstResponder) {
        return self;        
    }
    for (UIView *subView in self.subviews) {
        id responder = [subView findFirstResponder];
        if (responder) return responder;
    }
    return nil;
}
@end

iOS 7+

- (id)findFirstResponder
{
    if (self.isFirstResponder) {
        return self;
    }
    for (UIView *subView in self.view.subviews) {
        if ([subView isFirstResponder]) {
            return subView;
        }
    }
    return nil;
}

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