# Metric A named metric that carries a result value. ``` struct Metric ``` ## Overview Use `Metric` to define a named measurement. The factory methods (`passing`, `failing`, `scoring`, `ignore`) return a new `Metric` with the result stored inside. Here’s how you create a custom metric: ```swift let metric = Metric("Accuracy") let result = metric.passing(rationale: "Exact match") ``` ## Topics ### Creating a metric [`init(_:)`](/documentation/Evaluations/Metric/init(_:)) Creates a metric with just a name. ### Producing results [`passing(rationale:)`](/documentation/Evaluations/Metric/passing(rationale:)) Returns a metric with a passing result. [`failing(rationale:)`](/documentation/Evaluations/Metric/failing(rationale:)) Returns a metric with a failing result. [`scoring(_:rationale:)`](/documentation/Evaluations/Metric/scoring(_:rationale:)) Returns a metric with a numeric result. [`ignore(rationale:)`](/documentation/Evaluations/Metric/ignore(rationale:)) Returns a metric with an ignored result, excluded from aggregation. ### Inspecting a result [`name`](/documentation/Evaluations/Metric/name) The name of the metric, used as the DataFrame column name. [`value`](/documentation/Evaluations/Metric/value-swift.property) The result value of this metric. [`doubleValue`](/documentation/Evaluations/Metric/doubleValue) The numeric value of this metric. [`rationale`](/documentation/Evaluations/Metric/rationale) An optional rationale describing the result. [`Value`](/documentation/Evaluations/Metric/Value-swift.enum) A metric result value. ## Relationships ### Conforms To [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) [`Copyable`](/documentation/Swift/Copyable) [`Escapable`](/documentation/Swift/Escapable) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`Equatable`](/documentation/Swift/Equatable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)