---
title: "CFStringLowercase(_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfstringlowercase(_:_:)"
---

# CFStringLowercase(_:_:)

Changes all uppercase alphabetical characters in a CFMutableString to lowercase.

## Declaration

```swift
func CFStringLowercase(_ theString: CFMutableString!, _ locale: CFLocale!)
```

## Parameters

- `theString`: The string to be lowercased. If this value is not a CFMutableString object, an assertion is raised.
- `locale`: The locale to use when the lowercasing operation is performed. Prior to OS X v10.3 this parameter was an untyped pointer and not used. The locale argument affects the case mapping algorithm. For example, for the Turkish locale, case-insensitive compare matches “I” to “ı” (Unicode code point U+0131, Latin Small Dotless I), not the normal “i” character.

## Discussion

Discussion The locale parameter type changed from void * to CFLocaleRef in OS X v10.3.

## See Also

### CFMutableString Miscellaneous Functions

- [CFStringAppend(_:_:)](corefoundation/cfstringappend(_:_:).md)
- [CFStringAppendCharacters(_:_:_:)](corefoundation/cfstringappendcharacters(_:_:_:).md)
- [CFStringAppendCString(_:_:_:)](corefoundation/cfstringappendcstring(_:_:_:).md)
- [CFStringAppendFormatAndArguments(_:_:_:_:)](corefoundation/cfstringappendformatandarguments(_:_:_:_:).md)
- [CFStringAppendPascalString(_:_:_:)](corefoundation/cfstringappendpascalstring(_:_:_:).md)
- [CFStringCapitalize(_:_:)](corefoundation/cfstringcapitalize(_:_:).md)
- [CFStringCreateMutable(_:_:)](corefoundation/cfstringcreatemutable(_:_:).md)
- [CFStringCreateMutableCopy(_:_:_:)](corefoundation/cfstringcreatemutablecopy(_:_:_:).md)
- [CFStringCreateMutableWithExternalCharactersNoCopy(_:_:_:_:_:)](corefoundation/cfstringcreatemutablewithexternalcharactersnocopy(_:_:_:_:_:).md)
- [CFStringDelete(_:_:)](corefoundation/cfstringdelete(_:_:).md)
- [CFStringFindAndReplace(_:_:_:_:_:)](corefoundation/cfstringfindandreplace(_:_:_:_:_:).md)
- [CFStringFold(_:_:_:)](corefoundation/cfstringfold(_:_:_:).md)
- [CFStringInsert(_:_:_:)](corefoundation/cfstringinsert(_:_:_:).md)
- [CFStringNormalize(_:_:)](corefoundation/cfstringnormalize(_:_:).md)
- [CFStringPad(_:_:_:_:)](corefoundation/cfstringpad(_:_:_:_:).md)