# mxSignpostAnimationIntervalBegin(dso:log:name:signpostID:_:_:) Posts the start time of an animation interval to the log system. ``` func mxSignpostAnimationIntervalBegin(dso: UnsafeRawPointer = #dsohandle, log: OSLog, name: StaticString, signpostID: OSSignpostID = .exclusive, _ format: StaticString = "isAnimation=YES \n%{public, signpost:metrics}@", _ arguments: [any CVarArg] = [Unmanaged.fromOpaque(_MXSignpostMetricsSnapshot()).takeUnretainedValue()]) ``` ## Parameters `dso` A parameter for internal system use. `log` A log object to log the signpost to. `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` An array of arguments with a format string, followed by the expected number of arguments in the order that they appear in the string. ## Discussion Call this function to mark the beginning of an animation interval in the metric kit log. Provide a `log` that you create with [`makeLogHandle(category:)`](/documentation/MetricKit/MXMetricManager/makeLogHandle(category:)), a `name` for the event, and variable `arguments` for . Don’t alter the parameters `dso`, `signpostID`, or `format`. To end the interval, call [`mxSignpost(_:dso:log:name:signpostID:_:_:)`](/documentation/MetricKit/mxSignpost(_:dso:log:name:signpostID:_:_:)) with a `type` of `end`, passing the same `log`, `name`, and `signpostID` you used to begin it. --- 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)