UIKit 框架,有這么一個神奇的東西:accessibilityIdentifier

//
//  UIAccessibilityIdentification.h
//  UIKit
//
//  Copyright 2010-2012 Apple Inc. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <UIKit/UIView.h>
#import <UIKit/UIImage.h>
#import <UIKit/UIBarItem.h>

NS_ASSUME_NONNULL_BEGIN

@protocol UIAccessibilityIdentification <NSObject>
@required

/*
 A string that identifies the user interface element.
 default == nil
*/
@property(nullable, nonatomic, copy) NSString *accessibilityIdentifier NS_AVAILABLE_IOS(5_0);

@end

@interface UIView (UIAccessibility) <UIAccessibilityIdentification>
@end

@interface UIBarItem (UIAccessibility) <UIAccessibilityIdentification>
@end

/*
 Defaults to the filename of the image, if available.
 The default identifier for a UIImageView will be the identifier of its UIImage.
 */
@interface UIImage (UIAccessibility) <UIAccessibilityIdentification>
@end

NS_ASSUME_NONNULL_END

看注釋:A string that identifies the user interface element.default ==nil

意思是說: accessibilityIdentifier是UI元素的一個NSString 標識,#默認值是nil!#有點類似Cell 的ReuseIdentifier了,這也就好理解了;

來個簡單??:

UIImageView * picView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 90, 50, 50)];
    picView.image = [UIImage imageNamed:@"add_pic.png"];
    [picView.image setAccessibilityIdentifier:@"add”];

這個圖片 “add_pic.png” 的標記 就是 “add” ，當你更換picview的image時，如果不給AccessibilityIdentifier屬性重新復制的話，這個屬性的值就會變成nil(默認)，每個圖片都會對應一個專屬的AccessibilityIdentifier；方便我們識別圖片。

if ([picView.image.accessibilityIdentifier isEqualToString:@"add"]) {
        <#your code#>
    }else{
        <#your code#>
    }

這樣會方便很多，減少bool變量過多帶來的問題。