---
title: "MTSkyExpression | Mobile sdk | Mobile sdk ios | Ios"
description: "Expression element used to build MapTiler style expressions for sky values."
---

> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.

# MTSkyExpression

```
public enum MTSkyExpression : Sendable, Codable, Equatable
```

Expression element used to build MapTiler style expressions for sky values.

-   `[string(_:)](#/s:11MapTilerSDK15MTSkyExpressionO6stringyACSScACmF)`
    
    Undocumented
    
    #### Declaration
    
    Swift
    
    ```
    case string(String)
    ```
    
-   `[number(_:)](#/s:11MapTilerSDK15MTSkyExpressionO6numberyACSdcACmF)`
    
    Undocumented
    
    #### Declaration
    
    Swift
    
    ```
    case number(Double)
    ```
    
-   `[array(_:)](#/s:11MapTilerSDK15MTSkyExpressionO5arrayyACSayACGcACmF)`
    
    Undocumented
    
    #### Declaration
    
    Swift
    
    ```
    case array([MTSkyExpression])
    ```
    
-   `[init(from:)](#/s:Se4fromxs7Decoder_p_tKcfc)`
    
    #### Declaration
    
    Swift
    
    ```
    public init(from decoder: any Decoder) throws
    ```
    
-   `[encode(to:)](#/s:SE6encode2toys7Encoder_p_tKF)`
    
    #### Declaration
    
    Swift
    
    ```
    public func encode(to encoder: Encoder) throws
    ```