在Objective C中获取firstresponder [英] Get firstresponder in Objective C

问题描述

我在尝试找出哪个 UITextField 是当前的第一响应程序时遇到问题。

I am having trouble trying to figure out which UITextField is the current First Responder.

如果用户点击特定的 UITextField ，我想要做的是设置一个布尔值。所以要这样做，我需要能够告诉这个特定的文本字段是否已成为第一个响应者。

What I am trying to do is a set a boolean value if the user clicks in a particular UITextField. So to do that I need to be able to tell if this particular text field has become the first responder.

我知道如何设置第一个响应者，但不知道如何以确定字段是否实际上已成为第一个响应者。

I know how to set the first responder but just not sure how to tell if a field has actually become the first responder.

推荐答案

[...]但不知道如何判断字段是否
第一响应者。

[...] but just not sure how to tell if a field has actually become the first responder.

UIView 继承 isFirstResponder 方法从 UIResponder ，它告诉你这个。

UIView inherits the isFirstResponder method from UIResponder which tells you this.

找到第一个响应者的最简单方法是不检查单个控件/视图，并且没有多种方法可用于所有不同类型的可能的第一响应者。类别 UIView 其中添加 findFirstResponder 方法：

The easiest way to find whatever the first responder is without checking individual controls/views and without multiple methods for all of the different types of possible first responders is to just make a category on UIView which adds a findFirstResponder method:

UIView + FirstResponder.h

#import <UIKit/UIKit.h>

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

UIView + FirstResponder.m >

UIView+FirstResponder.m

#import "UIView+FirstResponder.h"

@implementation UIView (FirstResponder)

- (UIView *)findFirstResponder
{
    if ([self isFirstResponder])
        return self;

    for (UIView * subView in self.subviews) 
    {
        UIView * fr = [subView findFirstResponder];
        if (fr != nil)
            return fr;
    }

    return nil;
}

@end

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