A Boolean value that indicates whether the receiver uses heuristics when parsing a string.
- iOS 2.0+
- macOS 10.4+
- tvOS 9.0+
- watchOS 2.0+
YES if the receiver has been set to use heuristics when parsing a string to guess at the date which is intended, otherwise
If a formatter is set to be lenient, when parsing a string it uses heuristics to guess at the date which is intended. As with any guessing, it may get the result date wrong (that is, a date other than that which was intended).