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Overview

PollenService is a Swift actor that fetches pollen data from the Google Pollen API through a backend proxy. It provides detailed pollen information including pollen types (grass, tree, weed) and specific plant data with health recommendations. 
actor PollenService
Source: BreezeApp/Services/PollenService.swift:4

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Actor Isolation

This service is implemented as an actor to ensure thread-safe access to its methods and properties. All async methods are actor-isolated and can be safely called from any context.

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Shared Instance

static let shared = PollenService()
A singleton instance of the service that can be accessed throughout the application.

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Backend Proxy

The service uses a backend proxy URL instead of calling the Google Pollen API directly: 
private let baseURL = "https://breeze.earth/api/pollen"
This proxy handles API authentication and rate limiting, ensuring secure access to the Google Pollen API.

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Methods

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fetchPollen

Fetch comprehensive pollen data for a specific location. 
func fetchPollen(
    latitude: Double, 
    longitude: Double
) async throws -> [PollenItem]
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latitude
Double
required
The latitude of the location to fetch pollen data for
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longitude
Double
required
The longitude of the location to fetch pollen data for
Returns: [PollenItem] - An array of pollen items containing:
  • Pollen Types: General categories (Grass, Tree, Weed) with index values and categories
  • Specific Plants: Detailed information about individual plants including:
    • Display name and code
    • Index value and category (Low, Moderate, High, Very High)
    • Plant description with image URL
    • Family, season, and appearance information
    • Health recommendations
Throws:
  • URLError.badURL - If the URL cannot be constructed
  • URLError.badServerResponse - If the server returns a non-200 status code
  • DecodingError - If the response cannot be decoded
Implementation Details: The method processes the API response in two stages:
  1. Pollen Types: Extracts general pollen type information (grass, tree, weed)
  2. Plant Information: Extracts specific plant data with detailed descriptions
// Pollen types processing
if let pollenTypes = dailyInfo.pollenTypeInfo {
    for type in pollenTypes {
        items.append(PollenItem(
            id: type.code,
            name: type.displayName,
            value: type.indexInfo?.value ?? 0,
            category: type.indexInfo?.category ?? "Low",
            isPlant: false,
            // ... other properties
        ))
    }
}

// Specific plants processing
if let plants = dailyInfo.plantInfo {
    for plant in plants {
        items.append(PollenItem(
            id: plant.code,
            name: displayName,
            value: plant.indexInfo?.value ?? 0,
            category: plant.indexInfo?.category ?? "Low",
            isPlant: true,
            imageUrl: plant.plantDescription?.picture,
            // ... other properties
        ))
    }
}

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Usage Examples

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Basic Usage

let service = PollenService.shared

do {
    let pollenData = try await service.fetchPollen(
        latitude: 37.7749,
        longitude: -122.4194
    )
    
    for item in pollenData {
        print("\(item.name): \(item.category) (\(item.value))")
        
        if item.isPlant {
            print("  Plant family: \(item.family ?? "Unknown")")
            if let recommendations = item.healthRecommendations {
                print("  Health recommendations: \(recommendations)")
            }
        }
    }
} catch {
    print("Failed to fetch pollen data: \(error)")
}

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Separating Pollen Types and Plants

let service = PollenService.shared

do {
    let allItems = try await service.fetchPollen(
        latitude: 37.7749,
        longitude: -122.4194
    )
    
    // Separate pollen types from specific plants
    let pollenTypes = allItems.filter { !$0.isPlant }
    let plants = allItems.filter { $0.isPlant }
    
    print("=== Pollen Types ===")
    for type in pollenTypes {
        print("\(type.name): \(type.category)")
    }
    
    print("\n=== Specific Plants ===")
    for plant in plants {
        print("\(plant.name): \(plant.category)")
        if let imageUrl = plant.imageUrl {
            print("  Image: \(imageUrl)")
        }
    }
} catch {
    print("Error: \(error)")
}

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Display in SwiftUI

struct PollenView: View {
    @State private var pollenItems: [PollenItem] = []
    @State private var isLoading = false
    let latitude: Double
    let longitude: Double
    
    var body: some View {
        List {
            Section("Pollen Types") {
                ForEach(pollenItems.filter { !$0.isPlant }) { item in
                    PollenRowView(item: item)
                }
            }
            
            Section("Specific Plants") {
                ForEach(pollenItems.filter { $0.isPlant }) { item in
                    PlantRowView(item: item)
                }
            }
        }
        .overlay {
            if isLoading {
                ProgressView()
            }
        }
        .task {
            await loadPollenData()
        }
    }
    
    func loadPollenData() async {
        isLoading = true
        defer { isLoading = false }
        
        do {
            let service = PollenService.shared
            pollenItems = try await service.fetchPollen(
                latitude: latitude,
                longitude: longitude
            )
        } catch {
            print("Failed to load pollen data: \(error)")
        }
    }
}

struct PollenRowView: View {
    let item: PollenItem
    
    var body: some View {
        HStack {
            VStack(alignment: .leading) {
                Text(item.name)
                    .font(.headline)
                Text("Index: \(item.value)")
                    .font(.caption)
            }
            
            Spacer()
            
            Text(item.category)
                .padding(.horizontal, 8)
                .padding(.vertical, 4)
                .background(categoryColor)
                .foregroundColor(.white)
                .cornerRadius(8)
        }
    }
    
    var categoryColor: Color {
        switch item.category.lowercased() {
        case "low": return .green
        case "moderate": return .yellow
        case "high": return .orange
        case "very high": return .red
        default: return .gray
        }
    }
}

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Source Code

import Foundation

/// Service for fetching pollen data from Google Pollen API
actor PollenService {
    static let shared = PollenService()
    
    // Backend proxy URL - your production API
    private let baseURL = "https://breeze.earth/api/pollen"
    
    /// Fetch pollen data for a location via backend proxy
    func fetchPollen(latitude: Double, longitude: Double) async throws -> [PollenItem] {
        let urlString = "\(baseURL)?lat=\(latitude)&lon=\(longitude)"
        
        guard let url = URL(string: urlString) else {
            throw URLError(.badURL)
        }
        
        let (data, response) = try await URLSession.shared.data(from: url)
        
        guard let httpResponse = response as? HTTPURLResponse,
              httpResponse.statusCode == 200 else {
            throw URLError(.badServerResponse)
        }
        
        let decoder = JSONDecoder()
        let result = try decoder.decode(PollenResponse.self, from: data)
        
        var items: [PollenItem] = []
        
        if let dailyInfo = result.dailyInfo?.first {
            // Add pollen types (Grass, Tree, Weed)
            if let pollenTypes = dailyInfo.pollenTypeInfo {
                for type in pollenTypes {
                    items.append(PollenItem(
                        id: type.code,
                        name: type.displayName,
                        value: type.indexInfo?.value ?? 0,
                        category: type.indexInfo?.category ?? "Low",
                        isPlant: false,
                        imageUrl: nil,
                        family: nil,
                        season: nil,
                        appearance: nil,
                        healthRecommendations: type.healthRecommendations
                    ))
                }
            }
            
            // Add specific plants
            if let plants = dailyInfo.plantInfo {
                for plant in plants {
                    var displayName = plant.displayName
                    if plant.code == "GRAMINALES" {
                        displayName = "Graminales"
                    }
                    
                    items.append(PollenItem(
                        id: plant.code,
                        name: displayName,
                        value: plant.indexInfo?.value ?? 0,
                        category: plant.indexInfo?.category ?? "Low",
                        isPlant: true,
                        imageUrl: plant.plantDescription?.picture,
                        family: plant.plantDescription?.family,
                        season: plant.plantDescription?.season,
                        appearance: plant.plantDescription?.specialColors,
                        healthRecommendations: plant.healthRecommendations
                    ))
                }
            }
        }
        
        return items
    }
}

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Special Handling

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GRAMINALES Plant

The service includes special handling for the “GRAMINALES” plant code to ensure proper display formatting: 
if plant.code == "GRAMINALES" {
    displayName = "Graminales"
}

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Data Structure

The returned PollenItem objects distinguish between general pollen types and specific plants using the isPlant boolean:
  • isPlant: false: General pollen type (Grass, Tree, Weed)
    • No image, family, season, or appearance data
    • May include health recommendations
  • isPlant: true: Specific plant species
    • Includes detailed plant description
    • Image URL for visual identification
    • Family, season, and appearance information
    • Plant-specific health recommendations

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See Also

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