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Wesley de Groot
Wesley de Groot

Posted on • Originally published at wesleydegroot.nl on

Using MetricKit

#metrickit #swift

In this post, I will show you how to use MetricKit to collect and analyze performance data from your app.

What is MetricKit?

MetricKit is a framework introduced in iOS 13 that allows you to collect and analyze performance data from your app.

It provides a set of APIs to access metrics such as CPU usage, memory usage, disk I/O, and network I/O.

You can use this data to identify performance bottlenecks, optimize your app, and improve the user experience.

What metrics can you collect?

MetricKit provides APIs to collect the following metrics:

  • Diagnostics for crashes
  • Hangs
  • Energy
  • Disk writes

How to use MetricKit?

To use MetricKit in your app, you need to follow these steps:

Step 1: Import MetricKit 

import MetricKit
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Step 2: Register for metric updates

To receive metric updates, you need to create a class that conforms to the MXMetricManagerSubscriber protocol and register your class with the MXMetricManager singleton object in your app's main entry point.

@main struct DinnerConnectApp: App { private var metrics = MetricSubscriber() var body: some Scene { WindowGroup { MyAppView() .onAppear { MXMetricManager.shared.add(metrics) } } } }
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Step 3: Implement the MetricSubscriber protocol

We create a MetricSubscriber class that conforms to the MXMetricManagerSubscriber protocol to receive metric payloads.

class MetricSubscriber: NSObject, MXMetricManagerSubscriber { func didReceive(_ payloads: [MXMetricPayload]) { print("didReceive MXMetricPayload") guard let firstPayload = payloads.first else { return } if let jsonString = String( data: firstPayload.jsonRepresentation(), encoding: .utf8 ) { print(jsonString) } else { print("Failed to encode") } } func didReceive(_ payloads: [MXDiagnosticPayload]) { print("didReceive MXDiagnosticPayload") guard let firstPayload = payloads.first else { return } if let jsonString = String( data: firstPayload.jsonRepresentation(), encoding: .utf8 ) { print(jsonString) } else { print("Failed to encode") } } }
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Debugging MetricKit

MetricKit will only work on a real device, not on the simulator.

To send a metric payload to your app, you can go to Debug > Simulate MetricKit Payloads in Xcode.

References/resources:

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