---
title: lossySubstitutionKey
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/stringencodingdetectionoptionskey/lossysubstitutionkey
---

# lossySubstitutionKey

## Declaration

```swift
static let lossySubstitutionKey: StringEncodingDetectionOptionsKey
```

## Discussion

Discussion Option specifying the string used to substitute for any unsupported characters when converting to a lossy string encoding. If a @(NO) value is specified for NSStringEncodingDetectionAllowLossyKey, this option has no effect. The corresponding value for this key is an NSString object. By default, this value is U+FFFD.

## See Also

### Type Properties

- [allowLossyKey](foundation/stringencodingdetectionoptionskey/allowlossykey.md)
- [disallowedEncodingsKey](foundation/stringencodingdetectionoptionskey/disallowedencodingskey.md)
- [fromWindowsKey](foundation/stringencodingdetectionoptionskey/fromwindowskey.md)
- [likelyLanguageKey](foundation/stringencodingdetectionoptionskey/likelylanguagekey.md)
- [suggestedEncodingsKey](foundation/stringencodingdetectionoptionskey/suggestedencodingskey.md)
- [useOnlySuggestedEncodingsKey](foundation/stringencodingdetectionoptionskey/useonlysuggestedencodingskey.md)