decodeIntForKey

decodeIntForKey is a method used in object archiving to retrieve an integer value that was previously encoded with a corresponding key. It is part of the NSCoder family and is commonly used when implementing the NSCoding or NSKeyedArchiver/NSKeyedUnarchiver pattern to persist and restore objects.

Usage and language variations:

- In Objective-C, the method is typically invoked as [decoder decodeIntForKey:@"someKey"] and returns an int.

- In Swift, the equivalent call is decoder.decodeInt(forKey: "someKey") and it returns an Int.

The method relies on the same key being used during encoding with encodeInt:forKey: (Objective-C) or encodeInteger(_:forKey:) (Swift/NSCoder).

Behavior and considerations:

- The method decodes the value that was previously encoded for the given key. The decoding side and encoding side must agree on the key name and the data type.

- If the key is missing or the stored value cannot be interpreted as an integer, behavior can vary by framework version; many implementations will return a default (such as 0) or signal an error. It is prudent to ensure that the encoded data matches the expected type and key.

- This approach is part of older, non-JSON-based persistence in Cocoa and is often contrasted with newer Codable-based approaches. For new development, Codable with PropertyListEncoder/PropertyListDecoder or JSONEncoder/JSONDecoder is commonly recommended, with NSCoding retained for legacy code.

See also: encodeInt:forKey:, decodeBoolForKey:, NSCoding, NSKeyedArchiver, NSKeyedUnarchiver, NSCoder, Codable.