有没有办法检测什么UIView当前可见？ [英] Is there a way to detect what UIView is currently visible?

问题描述

我有一个类与Web服务进行通信，并在整个应用程序中使用。我正在寻找一种方法来显示一个错误消息在UIActionSheet在任何视图的用户之上。有一个简单的方法这样做吗？

I have a class that communicates with a web service and is used throughout the app. What I am looking for is a way to display an Error message in a UIActionSheet on top of what ever view the user is in. Is there an easy way to do this? I would like to avoid call back methods in every view if at all possible.

推荐答案

如果您在其他答案中使用代码，当您的应用程序提交到应用商店（使用非公共API）时，将被拒绝。我发现了硬的方式。一个更好的解决方案是创建一个类别。下面是我用来替换原始解决方案中的代码：

If you use the code in the other answer, your app will get rejected when submitted to the app store (for using a non-public api). I found that out the hard way. A better solution is to create a category. Here is what I used to replace the code in the original solution:

@interface UIView (FindFirstResponder)
- (UIView *)findFirstResponder;
@end

和

@implementation UIView (FindFirstResponder)
- (UIView *)findFirstResponder
{
    if (self.isFirstResponder) {        
        return self;     
    }

    for (UIView *subView in self.subviews) {
        UIView *firstResponder = [subView findFirstResponder];

        if (firstResponder != nil) {
            return firstResponder;
        }
    }

    return nil;
}
@end

这篇关于有没有办法检测什么UIView当前可见？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！