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# BuildSettingCondition

A condition that limits the application of a build setting.

```
struct BuildSettingCondition
```

## Overview

By default, build settings are applicable for all platforms and build
configurations. Use the `.when` modifier to define a build setting for a
specific condition. Invalid usage of `.when` emits an error during manifest
parsing. For example, it’s invalid to specify a `.when` condition with both
parameters as `nil`.

The following example shows how to use build setting conditions with various
APIs:

```swift
...
.target(
    name: "MyTool",
    dependencies: ["Utility"],
    cSettings: [
        .headerSearchPath("path/relative/to/my/target"),
        .define("DISABLE_SOMETHING", .when(platforms: [.iOS], configuration: .release)),
    ],
    swiftSettings: [
        .define("ENABLE_SOMETHING", .when(configuration: .release)),
    ],
    linkerSettings: [
        .linkedLibrary("openssl", .when(platforms: [.linux])),
    ]
),
```

## Topics

### Checking for a Build Condition

[`when(platforms:)`](/documentation/PackageDescription/BuildSettingCondition/when(platforms:))

Creates a build setting condition.

[`when(configuration:)`](/documentation/PackageDescription/BuildSettingCondition/when(configuration:))

Creates a build setting condition.

[`when(platforms:configuration:)`](/documentation/PackageDescription/BuildSettingCondition/when(platforms:configuration:)-475co)

Creates a build setting condition.

[`when(platforms:configuration:traits:)`](/documentation/PackageDescription/BuildSettingCondition/when(platforms:configuration:traits:))

Creates a build setting condition.

[`when(platforms:configuration:)`](/documentation/PackageDescription/BuildSettingCondition/when(platforms:configuration:)-2991l)

Creates a build setting condition.


---

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