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# Key-Path Expressions

Use key-path expressions to access properties dynamically.

## Topics

### Key Paths

[`KeyPath`](/documentation/Swift/KeyPath)

A key path from a specific root type to a specific resulting value type.

[`PartialKeyPath`](/documentation/Swift/PartialKeyPath)

A partially type-erased key path, from a concrete root type to any
resulting value type.

[`AnyKeyPath`](/documentation/Swift/AnyKeyPath)

A type-erased key path, from any root type to any resulting value
type.

### Writable Key Paths

[`WritableKeyPath`](/documentation/Swift/WritableKeyPath)

A key path that supports reading from and writing to the resulting value.

[`ReferenceWritableKeyPath`](/documentation/Swift/ReferenceWritableKeyPath)

A key path that supports reading from and writing to the resulting value
with reference semantics.


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