iOS SDK configuration

Autocapture configuration

You can enable or disable autocapture through the PostHogConfig object.

Flush configuration

The iOS SDK uses an internal queue to make calls fast and non-blocking. It also batches requests and flushes asynchronously, making it perfect to use in any part of your mobile app.

You can set the number of events in the configuration that should queue before flushing.

Setting this to 1 will send events immediately and will use more battery. This is set to 20 by default.

configuration.flushAt = 1

You can also manually flush the queue:

PostHogSDK.shared.capture("logged_out")
PostHogSDK.shared.flush()

Amending, dropping or sampling events

Since version 3.28.0, you can provide a BeforeSendBlock function when initializing the SDK to amend, drop or sample events before they are sent to PostHog.

⚠️ Note: This replaces the deprecated propertiesSanitizer option and provides more flexibility in modifying events. You can achieve the same functionality as propertiesSanitizer by using a BeforeSendBlock that mutates the event's properties in place.

🚨 Warning: Amending and sampling events is advanced functionality that requires careful implementation. Core PostHog features may require 100% of unmodified events to function properly. We recommend only modifying or sampling your own custom events if possible, and preserving all PostHog internal events in their original form.

Redacting information in events

BeforeSendBlock gives you one place to edit or redact information before it is sent to PostHog. For example:

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")

config.setBeforeSend { event in
    // Redact URLs
    if let url = event.properties["url"] as? String {
        event.properties["url"] = url.map { _ in "*" }.joined()
    }
    return event
}

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")

config.setBeforeSend { event in
    // Redact sensitive information
    if let email = event.properties["email"] as? String {
        event.properties["email"] = email.map { _ in "*" }.joined()
    }
    
    return event
}

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")

config.setBeforeSend { event in
    // Drop all events named "Stale Event"
    if event.event == "Stale Event" {
        return nil
    }
    return event
}

Sampling events

Sampling lets you choose to send only a percentage of events to PostHog. It is a good way to control your costs without having to completely turn off features of the SDK.

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")

config.setBeforeSend { event in
    // Sample 10% of Sampled Event events
    if event.event == "Sampled Event" {
        if Double.random(in: 0...1) < 0.1 {
            event.properties["$sample_type"] = ["sampleByEvent"]
            event.properties["$sample_threshold"] = 0.1
            event.properties["$sampled_events"] = ["Sampled Event"]
            return event
        }
        return nil
    }
    return event
}

Chaining multiple BeforeSendBlocks

You can provide an array of BeforeSendBlock functions to be called one after the other:

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")

config.setBeforeSend(
    // First block: Drop all events named "Stale Event"
    { event in
        if event.event == "Stale Event" {
            return nil
        }
        return event
    },
    // Second block: Redact sensitive information
    { event in
        if let email = event.properties["email"] as? String {
            event.properties["email"] = email.map { _ in "*" }.joined()
        }
        return event
    }
)

Note: When chaining beforeSend blocks, order is important. The first block is executed first and the mutated event is passed along to the second block, and so on. If at any point in the chain the event is dropped, any subsequent blocks will not be executed.

Setting up app groups

1. Configure App Groups: Set up an App Group in Xcode for your main app and extension targets
2. Configure PostHog: Use the same App Group identifier in all targets:

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")
config.appGroupIdentifier = "group.com.yourcompany.yourapp"
PostHogSDK.shared.setup(config)

Method swizzling

Method swizzling is a technique that enables the SDK to intercept and modify method calls at runtime to provide advanced features like screen view tracking, element interactions, session replay, surveys, and more.

Method swizzling is enabled by default, but can be disabled by setting the relevant config option to false in the PostHogConfig object:

Disabling all method swizzling

Since version 3.34.0, you can opt out of all swizzling using the enableSwizzling configuration option. When you disable swizzling, the SDK disables the features listed above.

let config = PostHogConfig(apiKey: "<ph_project_api_key>", host: "<ph_api_client_host>")
config.enableSwizzling = false
PostHogSDK.shared.setup(config)

Note: When method swizzling is disabled, features that depend on it will not work even if they are individually enabled in the config. For example, if you set config.sessionReplay = true and config.enableSwizzling = false, session replay will not be enabled.

Session metrics management

Method swizzling is particularly important for accurate session metrics tracking. With swizzling enabled, the SDK can better detect user activity and idle times to provide a better session rotation.

With swizzling disabled, the SDK only uses application open/backgrounded events to detect user activity, which can lead to a sub-optimal session calculation.

Custom keyboard extensions

Custom keyboard extensions have stricter security rules than other extension types. To use PostHog in a custom keyboard, the keyboard must have Open Access permission enabled. This permission is required for network requests and write access to shared containers.

Users must explicitly grant Open Access in Settings > General > Keyboard > Keyboards > [Your Keyboard] > Allow Full Access.

All configuration options

The PostHogConfig object contains several other settings you can toggle: