HealthStatisticsCollection# PRO

The HealthStatisticsCollection class provides a structured representation of time-based grouped health statistics, such as daily, weekly, or monthly summaries. Each entry in the collection corresponds to one interval, and encapsulates its own HealthStatistics object.

This class is particularly useful for:

• Plotting health trends over time
• Generating time-series reports
• Separating and accessing statistics by date intervals

#Overview

Each HealthStatisticsCollection is:

• Created by a time-based health statistics query
• Aligned using an anchor date and interval component (e.g., daily, weekly)
• Optionally aggregated by data source (e.g., app, device)

#Methods

#sources(): HealthSource[]

Returns an array of HealthSource objects that contributed data to this collection.

Each HealthSource represents a device or app that generated health samples (e.g., Apple Watch, iPhone, a third-party app).

#Example

const sources = collection.sources()
sources.forEach(source => {
  console.log("Source:", source.name, source.bundleIdentifier)
})

#statistics(): HealthStatistics[]

Returns all interval-based statistics in the collection as an array of HealthStatistics objects.

Each item represents one time interval, aligned by the query's anchorDate and intervalComponents.

#Example

const allStats = collection.statistics()
allStats.forEach(stat => {
  const value = stat.sumQuantity(HealthUnit.count())
  console.log(`From ${stat.startDate} to ${stat.endDate}: ${value} steps`)
})

#statisticsFor(date: Date): HealthStatistics | null

Returns the HealthStatistics object that contains the given date, if it falls within any of the predefined intervals in the collection.

If no interval includes the given date, it returns null.

#Example

const stat = collection.statisticsFor(new Date("2025-07-01"))
if (stat) {
  const value = stat.averageQuantity(HealthUnit.count())
  console.log("Average on July 1st:", value)
} else {
  console.log("No data for July 1st.")
}

#When to Use

Use HealthStatisticsCollection when:

• You want to break health data into intervals (e.g., by day/week/month)
• You need to retrieve and analyze health trends over time
• You're building graphs or dashboards from historical health data