The default implementation of this method raises an exception.
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
If conversion is successful, upon return contains the object created from
The string to parse.
nil, if there is a error during the conversion, upon return contains an
NSStringobject that describes the problem.
true if the conversion from string to cell content object was successful, otherwise
When implementing this method in a subclass, return by reference the object
an created from
string is equal to the value of the converted object, such as for formatters whose converted value type is
NSString, it can be returned by reference without creating a new object.
true if the conversion is successful. If you return
false, also return by indirection (in
error) a localized user-presentable
NSString object that explains the reason why the conversion failed; the delegate (if any) of the
NSControl object managing the cell can then respond to the failure in control:didFailToFormatString:errorDescription:. However, if
nil, the sender is not interested in the error description, and you should not attempt to assign one.
The following example (which is paired with the example given in
string(for:)) converts a string representation of a dollar amount that includes the dollar sign; it uses an
NSScanner instance to convert this amount to a float after stripping out the initial dollar sign.
Prior to OS X v10.6, the implementation of this method in both
Date would return
true and an object value even if only part of the string could be parsed. This is problematic because you cannot be sure what portion of the string was parsed. For applications linked on or after OS X v10.6, this method instead returns an error if part of the string cannot be parsed. You can use
get to get the old behavior—it returns the range of the substring that was successfully parsed.