NSSecureCoding trouble with collections of custom class

Question 1

I am having trouble with adopting NSSecureCoding. I encode an array containing objects of my custom class, which adoptsNSSecureCoding properly. When I decode it, passing the classNSArray (which is the class of the object I encoded), it throws an exception. However, when do theexact same thing with an array of strings, it works fine. I fail to see what is the difference between my class and NSString.

#import <Foundation/Foundation.h>@interface Foo : NSObject <NSSecureCoding>@end@implementation Foo- (id)initWithCoder:(NSCoder *)aDecoder {  return [super init];}- (void)encodeWithCoder:(NSCoder *)aCoder {}+ (BOOL)supportsSecureCoding {  return YES;}@endint main() {  @autoreleasepool {    NSMutableData* data = [[NSMutableData alloc] init];    NSKeyedArchiver* archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];    [archiver encodeObject:@[[Foo new]] forKey:@"foo"];    [archiver encodeObject:@[@"bar"] forKey:@"bar"];    [archiver finishEncoding];    NSKeyedUnarchiver* unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];    unarchiver.requiresSecureCoding = YES;    // throws exception: 'value for key 'NS.objects' was of unexpected class 'Foo'. Allowed classes are '{( NSArray )}'.'    [unarchiver decodeObjectOfClass:[NSArray class] forKey:@"foo"];    // but this line works fine:    [unarchiver decodeObjectOfClass:[NSArray class] forKey:@"bar"];    [unarchiver finishDecoding];  }  return 0;}

Question 2

Does this answer your question?Error of Unexpected class while encode/decode an NSArray with NSSecureCoding

Question 3

My solution was to usedecodeObjectOfClasses:forKey:

In Swift:

if let data = defaults.objectForKey(FinderSyncKey) as? NSData    let unArchiver = NSKeyedUnarchiver(forReadingWithData: data)    unArchiver.setRequiresSecureCoding(true)     //This line is most likely not needed, I was decoding the same object across modules    unArchiver.setClass(CustomClass.classForCoder(), forClassName: "parentModule.CustomClass")    let allowedClasses = NSSet(objects: NSArray.classForCoder(),CustomClass.classForCoder())    if let unarchived = unArchiver.decodeObjectOfClasses(allowedClasses, forKey:NSKeyedArchiveRootObjectKey) as?  [CustomClass]{        return unarchived    }    }

In Objective-C it would be something like:

[unArchiver decodeObjectOfClasses:allowedClasses forKey:NSKeyedArchiveRootObjectKey]

The change in decode object to decode objects solved the above exception for me.

Question 4

Thanks for this! My Objective-C version looks like:[coder decodeObjectOfClasses:[NSSet setWithObjects:[NSArray class], [MyCustomClass class], nil] forKey:key]; Very poor documentation on Apple's part, but works like a charm!

Question 5

Thank you so much.

Question 6

Thank you! Really helped fixing a warning for iOS 15.

Question 7

I was really struggling with this for an hour in Swift 5.

My situation was I had a Set of custom Solution objects:

var resultsSet = Set<Solution>()

Which conformed to Secure Coding:

static var supportsSecureCoding: Bool{ get{ return true } }

Their container object encoded them as an NSSet, because of Secure Coding:

aCoder.encode(resultsSet as NSSet, forKey: "resultsSet")

But I always got a complier error during decoding:

if let decodedResultsSet = aDecoder.decodeObject(of: NSSet.self, forKey: "resultsSet"){    resultsSet = decodedResultsSet as! Set<Solution>}

Error:

2020-02-11 22:35:06.555015+1300 Exception occurred restoring state value for key 'NS.objects' was of unexpected class 'App.Solution'. Allowed classes are '{(NSSet)}'.2020-02-11 22:35:06.564758+1300 *** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'value for key 'NS.objects' was of unexpected class 'App.Solution'. Allowed classes are '{(NSSet)}'.'

If I changed the decodeObject(ofClass: to Solution:

if let decodedResultsSet = aDecoder.decodeObject(of: Solution.self, forKey: "resultsSet"){    resultsSet = decodedResultsSet as! Set<Solution>}

I get the error:

2020-02-11 22:33:46.924580+1300 Exception occurred restoring state value for key 'resultsSet' was of unexpected class 'NSSet'. Allowed classes are '{(app.Solution)}'.2020-02-11 22:33:46.933812+1300 *** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'value for key 'resultsSet' was of unexpected class 'NSSet'. Allowed classes are '{(app.Solution)}'.'

The answer, which is obvious now, but I could find it anywhere was to realise the allowed object list is an array, and it needs both NSSet and the custom object: Solution.

if let decodedResultsSet = aDecoder.decodeObject(of: [NSSet.self, Solution.self], forKey: "resultsSet"){    resultsSet = decodedResultsSet as! Set<Solution>}

Question 8

I had the same problem in Swift with iOS 15 / Xcode 13.2.I solved it by simply adding NSNumber (the offending class listed in the warning) in the decoder.decodeObject of required init(coder decoder: NSCoder) { }(I edited the class names). MyVar contains some numbers.

required init(coder decoder: NSCoder) {        myVar = decoder.decodeObject(of: [MyType.self, NSNumber.self], forKey: theKey) as? [MyVar] ?? []}

utahwithak 6,3553 gold badges44 silver badges64 bronze badges · Accepted Answer · 2024-05-16 02:50:42Z

My solution was to usedecodeObjectOfClasses:forKey:

In Swift:

if let data = defaults.objectForKey(FinderSyncKey) as? NSData    let unArchiver = NSKeyedUnarchiver(forReadingWithData: data)    unArchiver.setRequiresSecureCoding(true)     //This line is most likely not needed, I was decoding the same object across modules    unArchiver.setClass(CustomClass.classForCoder(), forClassName: "parentModule.CustomClass")    let allowedClasses = NSSet(objects: NSArray.classForCoder(),CustomClass.classForCoder())    if let unarchived = unArchiver.decodeObjectOfClasses(allowedClasses, forKey:NSKeyedArchiveRootObjectKey) as?  [CustomClass]{        return unarchived    }    }

In Objective-C it would be something like:

[unArchiver decodeObjectOfClasses:allowedClasses forKey:NSKeyedArchiveRootObjectKey]

The change in decode object to decode objects solved the above exception for me.

Thanks for this! My Objective-C version looks like:[coder decodeObjectOfClasses:[NSSet setWithObjects:[NSArray class], [MyCustomClass class], nil] forKey:key]; Very poor documentation on Apple's part, but works like a charm!

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NSSecureCoding trouble with collections of custom class

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