decodeIntegerForKey

decodeIntegerForKey is a method of the NSCoder family used to retrieve an integer value associated with a given key from an encoded data stream or archive. It is commonly used when unarchiving objects that were previously encoded with a corresponding encodeInteger:forKey: or related integer-encoding methods. The value returned is the integer (NSInteger) that was stored under the specified key.

In Objective-C, the method signature is typically - (NSInteger)decodeIntegerForKey:(NSString *)key;. In Swift, this capability is exposed as a decodable integer forKey variant on NSCoder or NSKeyedUnarchiver, often used as coder.decodeInteger(forKey: "key"). The method requires that the data for the key was encoded as an integer; using it with a key that was not encoded as an integer may lead to undefined behavior or runtime errors, depending on the framework and context.

Usage example:

Objective-C: NSInteger count = [decoder decodeIntegerForKey:@"count"];

Swift: let count = decoder.decodeInteger(forKey: "count")

Related methods include encodeInteger:forKey: and encodeInt:forKey: for writing, as well as decodeBoolForKey:, decodeDoubleForKey:, and decodeObjectForKey: for other data types. When designing archives, it is important to pair each decodeIntegerForKey: with a corresponding encodeInteger:forKey: to preserve data integrity and type safety.