# NSSecureCoding A protocol that enables encoding and decoding in a manner that is robust against object substitution attacks. ``` protocol NSSecureCoding : NSCoding ``` ## Overview Historically, many classes decoded instances of themselves like this: ```objc id obj = [decoder decodeObjectForKey:@"myKey"]; if (![obj isKindOfClass:[MyClass class]]) { /* ...fail... */ } ``` This technique is potentially unsafe because by the time you can verify the class type, the object has already been constructed, and if this is part of a collection class, potentially inserted into an object graph. In order to conform to [`NSSecureCoding`](/documentation/Foundation/NSSecureCoding): - An object that does not override [`init(coder:)`](/documentation/Foundation/NSCoding/init(coder:)) can conform to `NSSecureCoding` without any changes (assuming that it is a subclass of another class that conforms). - An object that does override [`init(coder:)`](/documentation/Foundation/NSCoding/init(coder:)) must decode any enclosed objects using the [`decodeObjectOfClass:forKey:`](/documentation/Foundation/NSCoder/decodeObjectOfClass:forKey:) method. For example: ```objc id obj = [decoder decodeObjectOfClass:[MyClass class] forKey:@"myKey"]; ``` In addition, the class must override the getter for its [`supportsSecureCoding`](/documentation/Foundation/NSSecureCoding/supportsSecureCoding) property to return . For more information about how this relates to the NSXPC API, see [Creating XPC Services](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingXPCServices.html#//apple_ref/doc/uid/10000172i-SW6) in [Daemons and Services Programming Guide](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/Introduction.html#//apple_ref/doc/uid/10000172i). ## Topics ### Checking for Secure Coding [`static var supportsSecureCoding: Bool`](/documentation/Foundation/NSSecureCoding/supportsSecureCoding) A Boolean value that indicates whether or not the class supports secure coding. ## Relationships ### Conforming Types [`NSHashTable`](/documentation/Foundation/NSHashTable) [`UnitSpeed`](/documentation/Foundation/UnitSpeed) [`NSMutableData`](/documentation/Foundation/NSMutableData) [`NSLocale`](/documentation/Foundation/NSLocale) [`NSPredicate`](/documentation/Foundation/NSPredicate) [`UnitElectricCurrent`](/documentation/Foundation/UnitElectricCurrent) [`NSNumber`](/documentation/Foundation/NSNumber) [`NSMutableDictionary`](/documentation/Foundation/NSMutableDictionary) [`UnitElectricPotentialDifference`](/documentation/Foundation/UnitElectricPotentialDifference) [`NSMutableIndexSet`](/documentation/Foundation/NSMutableIndexSet) [`ISO8601DateFormatter`](/documentation/Foundation/ISO8601DateFormatter) [`URLCredential`](/documentation/Foundation/URLCredential) [`NSIndexSet`](/documentation/Foundation/NSIndexSet) [`NSExtensionItem`](/documentation/Foundation/NSExtensionItem) [`NSDateInterval`](/documentation/Foundation/NSDateInterval) [`NSIndexPath`](/documentation/Foundation/NSIndexPath) [`UnitDispersion`](/documentation/Foundation/UnitDispersion) [`NSPointerArray`](/documentation/Foundation/NSPointerArray) [`UnitPressure`](/documentation/Foundation/UnitPressure) [`NSMutableOrderedSet`](/documentation/Foundation/NSMutableOrderedSet) [`NSOrderedSet`](/documentation/Foundation/NSOrderedSet) [`NSMutableString`](/documentation/Foundation/NSMutableString) [`NSTimeZone`](/documentation/Foundation/NSTimeZone) [`NSURLQueryItem`](/documentation/Foundation/NSURLQueryItem) [`HTTPURLResponse`](/documentation/Foundation/HTTPURLResponse) [`NSDataDetector`](/documentation/Foundation/NSDataDetector) [`NSCharacterSet`](/documentation/Foundation/NSCharacterSet) [`UnitConverterLinear`](/documentation/Foundation/UnitConverterLinear) [`Unit`](/documentation/Foundation/Unit) [`UnitVolume`](/documentation/Foundation/UnitVolume) [`NSDecimalNumber`](/documentation/Foundation/NSDecimalNumber) [`NSCompoundPredicate`](/documentation/Foundation/NSCompoundPredicate) [`URLResponse`](/documentation/Foundation/URLResponse) [`NSAppleEventDescriptor`](/documentation/Foundation/NSAppleEventDescriptor) [`NSAffineTransform`](/documentation/Foundation/NSAffineTransform) [`CachedURLResponse`](/documentation/Foundation/CachedURLResponse) [`NSURL`](/documentation/Foundation/NSURL) [`UnitLength`](/documentation/Foundation/UnitLength) [`NSRegularExpression`](/documentation/Foundation/NSRegularExpression) [`FileWrapper`](/documentation/Foundation/FileWrapper) [`NSMutableAttributedString`](/documentation/Foundation/NSMutableAttributedString) [`NSAttributedString`](/documentation/Foundation/NSAttributedString) [`NSString`](/documentation/Foundation/NSString) [`NSArray`](/documentation/Foundation/NSArray) [`UnitArea`](/documentation/Foundation/UnitArea) [`NSMutableArray`](/documentation/Foundation/NSMutableArray) [`UnitMass`](/documentation/Foundation/UnitMass) [`UnitEnergy`](/documentation/Foundation/UnitEnergy) [`NSSortDescriptor`](/documentation/Foundation/NSSortDescriptor) [`NSPersonNameComponents`](/documentation/Foundation/NSPersonNameComponents) [`MeasurementFormatter`](/documentation/Foundation/MeasurementFormatter) [`NSCountedSet`](/documentation/Foundation/NSCountedSet) [`UnitTemperature`](/documentation/Foundation/UnitTemperature) [`NSMutableURLRequest`](/documentation/Foundation/NSMutableURLRequest) [`NSOrthography`](/documentation/Foundation/NSOrthography) [`UnitAcceleration`](/documentation/Foundation/UnitAcceleration) [`UnitAngle`](/documentation/Foundation/UnitAngle) [`NSMapTable`](/documentation/Foundation/NSMapTable) [`NSError`](/documentation/Foundation/NSError) [`UnitPower`](/documentation/Foundation/UnitPower) [`UnitInformationStorage`](/documentation/Foundation/UnitInformationStorage) [`NSData`](/documentation/Foundation/NSData) [`UnitIlluminance`](/documentation/Foundation/UnitIlluminance) [`NSFileSecurity`](/documentation/Foundation/NSFileSecurity) [`UnitFrequency`](/documentation/Foundation/UnitFrequency) [`UnitFuelEfficiency`](/documentation/Foundation/UnitFuelEfficiency) [`EnergyKit`](/documentation/Foundation/UnitEnergy/EnergyKit) [`NSNull`](/documentation/Foundation/NSNull) [`NSMeasurement`](/documentation/Foundation/NSMeasurement) [`NSURLRequest`](/documentation/Foundation/NSURLRequest) [`NSTextCheckingResult`](/documentation/Foundation/NSTextCheckingResult) [`NSDate`](/documentation/Foundation/NSDate) [`URLProtectionSpace`](/documentation/Foundation/URLProtectionSpace) [`NSXPCListenerEndpoint`](/documentation/Foundation/NSXPCListenerEndpoint) [`NSValue`](/documentation/Foundation/NSValue) [`UnitConcentrationMass`](/documentation/Foundation/UnitConcentrationMass) [`NSException`](/documentation/Foundation/NSException) [`NSMutableCharacterSet`](/documentation/Foundation/NSMutableCharacterSet) [`NSMutableSet`](/documentation/Foundation/NSMutableSet) [`UnitElectricCharge`](/documentation/Foundation/UnitElectricCharge) [`NSComparisonPredicate`](/documentation/Foundation/NSComparisonPredicate) [`UnitDuration`](/documentation/Foundation/UnitDuration) [`NSCalendar`](/documentation/Foundation/NSCalendar) [`URLAuthenticationChallenge`](/documentation/Foundation/URLAuthenticationChallenge) [`Dimension`](/documentation/Foundation/Dimension) [`FileHandle`](/documentation/Foundation/FileHandle) [`UnitElectricResistance`](/documentation/Foundation/UnitElectricResistance) [`NSSet`](/documentation/Foundation/NSSet) [`NSDictionary`](/documentation/Foundation/NSDictionary) [`NSPurgeableData`](/documentation/Foundation/NSPurgeableData) [`NSUUID`](/documentation/Foundation/NSUUID) [`NSDateComponents`](/documentation/Foundation/NSDateComponents) [`NSExpression`](/documentation/Foundation/NSExpression) ### Inherits From [`NSCoding`](/documentation/Foundation/NSCoding) --- Copyright © 2026 Apple Inc. 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