如何为存储在 Core Data 中的属性字符串实现 NSAttributedStringValueTransformer

如何解决如何为存储在 Core Data 中的属性字符串实现 NSAttributedStringValueTransformer

我有一个应用程序，它使用 Core Data 中的 Transformable 属性来存储 NSAttributedStrings 并获取编译器警告

Object.property is using a nil or insecure value transformer. Please switch to NSSecureUnarchiveFromDataTransformerName or a custom NSValueTransformer subclass of NSSecureUnarchiveFromDataTransformer [2]

NSSecureUnarchiveFromDataTransformerName 不支持 NSAttributedStrings 的存档和解档，据我所知，我必须创建一个自定义转换器，在 AppDelegate 中注册，并在核心数据模型对象属性详细信息中输入转换器类名称。

下面是自定义转换器类，但是在尝试解码现有属性字符串时出现错误。任何人都可以对此有所了解吗？为什么新的解压器无法处理 NSFileWrapper，因为这是 NSTextAttachment 的一个属性，并且可以与已弃用的解压器配合使用？

这是一个错误还是故意的？

有什么方法可以支持解压 NSFileWrapper 吗？

@implementation NSAttributedStringValueTransformer
+(Class)transformedValueClass {
    return [NSAttributedString class];
}
+(void)initialize {
    [NSValueTransformer setValueTransformer:[[self alloc]init] forName:@"NSAttributedStringValueTransformer"];
}

+(BOOL)allowsReverseTransformation {
    return YES;
}

-(NSData*)transformedValue:(NSAttributedString*)value {
    NSError *error;
    NSData* stringAsData = [NSKeyedArchiver archivedDataWithRootObject:value requiringSecureCoding:false error:&error];
    if (error != nil) {
        NSLog(@"Error encoding attributed string: %@",error.localizedDescription);
        return nil;
    }
    return stringAsData;
}

-(NSAttributedString*)reverseTransformedValue:(NSData*)value {
    NSError *error;
    
    // This works
    // NSAttributedString* string = [NSKeyedUnarchiver unarchiveObjectWithData: value];
    
    // This fails with the error 'The data Couldn’t be read because it isn’t in the correct format.'
    NSAttributedString* string = [NSKeyedUnarchiver unarchivedobjectOfClass:[NSAttributedString class] fromData:value error:&error];
    
    
    if (error != nil) {
        NSLog(@"Error decoding attributed string: %@",error);
        return nil;
    }
    return string;
}
@end

导致的错误：

Error decoding attributed string: Error Domain=NSCocoaErrorDomain Code=4864 "value for key 'NSFileWrapper' was of unexpected class 'NSFileWrapper (0x1c9d40d48) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]'. Allowed classes are '{(
    "NSURL (0x1c9d1b988) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreFoundation.framework]","NSAttributedString (0x1c9d36668) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]","NSFont (0x1c9e1a3c8) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIFoundation.framework]","NSDictionary (0x1c9d1adf8) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreFoundation.framework]","NSArray (0x1c9d1ab28) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreFoundation.framework]","NSColor (0x1c9ec2198) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIKitCore.framework]","NSTextAttachment (0x1c9e1aad0) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIFoundation.framework]","NSGlyphInfo (0x1c9e198d8) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIFoundation.framework]","NSParagraphStyle (0x1c9e19db0) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIFoundation.framework]","Nsstring (0x1c9d3e868) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]","UIFont (0x1c9e1acb0) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIFoundation.framework]","UIColor (0x1c9ec25f8) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/UIKitCore.framework]","NSNumber (0x1c9d3f510) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]"
)}'." UserInfo={NSDebugDescription=value for key 'NSFileWrapper' was of unexpected class 'NSFileWrapper (0x1c9d40d48) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]'. Allowed classes are '{(
    "NSURL (0x1c9d1b988) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreFoundation.framework]","NSNumber (0x1c9d3f510) [/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Foundation.framework]"
)}'.}