# mxSignpost(_:dso:log:name:signpostID:_:_:) Posts a single custom metric, the start time of a custom metric, or the end time of a custom metric to the log system. ``` func mxSignpost(_ type: OSSignpostType, dso: UnsafeRawPointer = #dsohandle, log: OSLog, name: StaticString, signpostID: OSSignpostID = .exclusive, _ format: StaticString = "%{public, signpost:metrics}@", _ arguments: [any CVarArg] = [Unmanaged.fromOpaque(_MXSignpostMetricsSnapshot()).takeUnretainedValue()]) ``` ## Parameters `type` A value that represents the type of the signpost: - `event`: A single custom metric. - `begin`: The start time of a custom metric. - `end`: The end time of a custom metric. `dso` A parameter for internal system use. `log` A log for the category of the event that was created previously using [`makeLogHandle(category:)`](/documentation/MetricKit/MXMetricManager/makeLogHandle(category:)). `name` A string containing the developer-assigned name of the custom event. `signpostID` A parameter for internal system use. `format` A parameter for internal system use. `arguments` The variable arguments for . ## Discussion Call this function to mark a custom metric, custom metric start time, or custom metric end time in the metric kit log. Provide a `log` that you create with [`makeLogHandle(category:)`](/documentation/MetricKit/MXMetricManager/makeLogHandle(category:)), the `type` of the event, a `name` for the event, and variable `arguments` for . Don’t alter the parameters `dso`, `signpostID`, or `format`. --- 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)