The floating-point value of the string as a
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
This property doesn’t include any whitespace at the beginning of the string. This property is
–HUGE_VAL on overflow,
0 on underflow. This property is
0 if the string doesn’t begin with a valid text representation of a floating-point number.
This property uses formatting information stored in the non-localized value; use an
Scanner object for localized scanning of numeric values from a string.