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Unexpected class error when encoding / decoding NSArray with NSSecureCoding

Background

We have several classes that follow the protocol NSSecureCoding

.

@interface ClassA : NSObject <NSSecureCoding>
// ...
@end

@interface ClassB : NSObject <NSSecureCoding>
// ...
@end

Note that it NSArray

also matches NSSecureCoding

. Therefore, we try to do the following.

For encoding:

NSArray* array = ...
[archiver encodeObject:array forKey:@"AirdropDataKey"];

For decoding

NSArray* array = [unarchiver decodeObjectOfClass:[NSArray class] 
                                          forKey:@"AirdropDataKey"];

And I am getting the following error.

Application terminated due to uncaught exception "NSInvalidUnarchiveOperationException", reason: "The value for key" NS.objects "was unexpected class" ClassA ". Valid classes: {{NSArray
)} ''

Can anyone please explain why and can this problem be solved?

Edit

I think I figured it out. Please refer to my underwriter in the following message. Good luck ~

Strange behavior when decoding NSArray via NSSecureCoding

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2 answers


NSCoder

provides an additional method decodeObjectOfClasses:forKey:

where a set of expected objects can be passed. This allows you to decode nested structures.

Just pass the set with NSArray

both yours ClassA

and ClassB

class:



NSSet *classes = [NSSet setWithObjects:[NSArray class], [ClassA class] ,[ClassB class], nil];
NSArray* array = [unarchiver decodeObjectOfClasses:classes forKey:@"AirdropDataKey"];
+4


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For decoding use below method and check: -



 - (id)decodeObjectForKey:(NSString *)key
0


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