---
title: "CFStringCreateWithSubstring(_:_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfstringcreatewithsubstring(_:_:_:)"
---

# CFStringCreateWithSubstring(_:_:_:)

Creates an immutable string from a segment (substring) of an existing string.

## Declaration

```swift
func CFStringCreateWithSubstring(_ alloc: CFAllocator!, _ str: CFString!, _ range: CFRange) -> CFString!
```

## Parameters

- `alloc`: The allocator to use to allocate memory for the new string. Pass NULL or doc://com.apple.corefoundation/documentation/CoreFoundation/kCFAllocatorDefault to use the current default allocator.
- `str`: The string from which to create the new string.
- `range`: The range of characters in str to copy. The specified range must not exceed the length of the string.

## Return Value

Return Value An immutable string, or NULL if there was a problem creating the object. Ownership follows the The Create Rule.

## See Also

### Creating a CFString

- [CFStringCreateArrayBySeparatingStrings(_:_:_:)](corefoundation/cfstringcreatearraybyseparatingstrings(_:_:_:).md)
- [CFStringCreateByCombiningStrings(_:_:_:)](corefoundation/cfstringcreatebycombiningstrings(_:_:_:).md)
- [CFStringCreateCopy(_:_:)](corefoundation/cfstringcreatecopy(_:_:).md)
- [CFStringCreateFromExternalRepresentation(_:_:_:)](corefoundation/cfstringcreatefromexternalrepresentation(_:_:_:).md)
- [CFStringCreateWithBytes(_:_:_:_:_:)](corefoundation/cfstringcreatewithbytes(_:_:_:_:_:).md)
- [CFStringCreateWithBytesNoCopy(_:_:_:_:_:_:)](corefoundation/cfstringcreatewithbytesnocopy(_:_:_:_:_:_:).md)
- [CFStringCreateWithCharacters(_:_:_:)](corefoundation/cfstringcreatewithcharacters(_:_:_:).md)
- [CFStringCreateWithCharactersNoCopy(_:_:_:_:)](corefoundation/cfstringcreatewithcharactersnocopy(_:_:_:_:).md)
- [CFStringCreateWithCString(_:_:_:)](corefoundation/cfstringcreatewithcstring(_:_:_:).md)
- [CFStringCreateWithCStringNoCopy(_:_:_:_:)](corefoundation/cfstringcreatewithcstringnocopy(_:_:_:_:).md)
- [CFStringCreateWithFormatAndArguments(_:_:_:_:)](corefoundation/cfstringcreatewithformatandarguments(_:_:_:_:).md)
- [CFStringCreateWithPascalString(_:_:_:)](corefoundation/cfstringcreatewithpascalstring(_:_:_:).md)
- [CFStringCreateWithPascalStringNoCopy(_:_:_:_:)](corefoundation/cfstringcreatewithpascalstringnocopy(_:_:_:_:).md)