decodeIntegerForKeysomeKey

decodeIntegerForKey: is a method provided by NSCoder and its concrete subclass NSKeyedUnarchiver used to retrieve an integer value that was previously encoded in an archived object. The method requires a single argument, key, which identifies the encoded value in the archive. It returns an NSInteger representing the decoded value.

In practice, this method is commonly used inside the decoding initializer of a class that conforms to NSCoding or NSSecureCoding. The typical pattern is to call decodeIntegerForKey: (or its Swift equivalent decodeInteger(forKey:)) for each integer property that was encoded with encodeInteger:forKey: (or encodeInt:forKey:). The key used during decoding must match exactly the key used during encoding to ensure the correct value is retrieved.

Return semantics and caveats: If no value has been encoded for the specified key, or if the stored value cannot be interpreted as an integer, decodeIntegerForKey: returns 0. Therefore, it is important to design the encoding step to include all required keys and to distinguish between an actual 0 value and a missing key when interpreting results. In secure coding contexts, you should ensure keys and types align with the expected schema to avoid inconsistencies during decoding.

See also: NSCoding, NSSecureCoding, NSCoder, NSKeyedUnarchiver, encodeInteger:forKey:, decodeObjectForKey:, decodeBoolForKey:.