I tried to read an Object :
-(NSMutableDictionary*) readMyObject:(NSData*)data;
{
NSError * error;
Class class = [NSMutableDictionary class];
NSMutableDictionary * dict;
dict = [NSKeyedUnarchiver unarchivedObjectOfClass:class
fromData:data error:&error];
return dict;
the result was nil.
I searched by Developer for a solution and found one :
{
// NSKeyedUnarchiver * unarchiver = [[NSKeyedUnarchiver alloc] init];
[unarchiver decodeObjectOfClasses:
[[NSSet alloc]initWithArray:
@[[NSDictionary class],
[NSMutableDictionary class],
[NSArray class],
[NSMutableArray class],
[NSString class], [NSNumber class]]]
forKey:NSKeyedArchiveRootObjectKey];
[unarchiver finishDecoding];
}
The first line was from me and it crashed the project.
I assume there is an easy answer, not for me.🥲 Uwe
There are two cases to consider here. First, consider a custom object like this:
@interface MyObject : NSObject <NSSecureCoding>
@property (nonatomic, copy, readwrite, nullable) NSString * myProperty;
@end
You implement secure coding support like this:
+ (BOOL)supportsSecureCoding {
return YES;
}
- (nullable instancetype)initWithCoder:(nonnull NSCoder *)coder {
self = [super init];
if (self != nil) {
self->_myProperty = [[coder decodeObjectOfClass:[NSString class] forKey:@"myProperty"] copy];
}
return self;
}
- (void)encodeWithCoder:(nonnull NSCoder *)coder {
[coder encodeObject:self.myProperty forKey:@"myProperty"];
}
And then encode and decode like this:
MyObject * obj = [[MyObject alloc] init];
obj.myProperty = @"Hello Cruel World!";
NSData * archive = [NSKeyedArchiver archivedDataWithRootObject:obj requiringSecureCoding:true error: nil];
MyObject * obj2 = [NSKeyedUnarchiver unarchivedObjectOfClass:[MyObject class] fromData:archive error:nil];
The second case relates to collections, where you have to authorise the decoding of both the container and the items within the container. I have an example of this here, albeit one in Swift. Fortunately the take-home point — the need to use +unarchivedObjectOfClasses:fromData:error: — is pretty clear.
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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