iOS下解析Geo数据提取经纬度并入字典数组技术求助

Got it, let's break this down step by step. You've successfully fetched and started parsing the JSON data—now we just need to extract the longitude and latitude from that A_Geo string format and add those values to your Article objects.

1. First, write a helper function to parse the Geo string #

The A_Geo value is in the format "MULTIPOINT ((lng lat))", so we need to strip out the extra characters and split the remaining string into two numerical values:

func parseGeoCoordinates(from geoString: String) -> (longitude: Double?, latitude: Double?) {
    // Clean up the string by removing the "MULTIPOINT (" and trailing "))"
    let cleaned = geoString.replacingOccurrences(of: "MULTIPOINT ((", with: "")
                           .replacingOccurrences(of: "))", with: "")
                           .trimmingCharacters(in: .whitespaces)
    
    // Split the cleaned string into two parts using whitespace as the separator
    let coords = cleaned.components(separatedBy: .whitespaces)
    guard coords.count == 2,
          let lng = Double(coords[0]),
          let lat = Double(coords[1]) else {
        // Return nil if parsing fails (invalid format or non-numeric values)
        return (nil, nil)
    }
    return (lng, lat)
}

2. Update your JSON parsing logic #

In the loop where you process each articleDict, call the helper function to get the lng/lat, then add those values to the dictionary before initializing an Article. I also adjusted the error handling a bit to be more explicit instead of using try? (which can hide issues):

let task = session.dataTask(with: ArticlesUrl){(data,response,error) in
    if let error = error {
        print("Failed to fetch data: \(error.localizedDescription)")
        completionHandler(nil, error)
        return
    }
    
    guard let data = data else {
        let noDataError = NSError(domain: "DataFetchError", code: 1, userInfo: [NSLocalizedDescriptionKey: "No data received from server"])
        completionHandler(nil, noDataError)
        return
    }
    
    do {
        guard let jsonObject = try JSONSerialization.jsonObject(with: data) as? [String: Any],
              let resultDict = jsonObject["result"] as? [String: Any],
              let articleArray = resultDict["results"] as? [[String: Any]] else {
            let parseError = NSError(domain: "JSONParseError", code: 2, userInfo: [NSLocalizedDescriptionKey: "Invalid JSON structure"])
            completionHandler(nil, parseError)
            return
        }
        
        var articles = [Article]()
        for articleDict in articleArray {
            // Make a mutable copy of the dict so we can add lng/lat
            var mutableDict = articleDict
            
            // Parse the geo coordinates if A_Geo exists
            if let geoString = articleDict["A_Geo"] as? String {
                let (lng, lat) = parseGeoCoordinates(from: geoString)
                mutableDict["lng"] = lng
                mutableDict["lat"] = lat
            }
            
            // Initialize Article with the updated dict
            let article = Article(rawData: mutableDict)
            articles.append(article)
        }
        
        completionHandler(articles, nil)
    } catch let parseError {
        print("JSON parsing failed: \(parseError.localizedDescription)")
        completionHandler(nil, parseError)
    }
}
task.resume()

3. Update your Article model #

Make sure your Article class has properties to store the longitude and latitude, and that the initializer pulls those values from the raw data dict:

class Article {
    let articleID: String
    let nameChinese: String
    let location: String
    let nameEnglish: String
    let cid: String
    var longitude: Double?
    var latitude: Double?
    
    init(rawData: [String: Any]) {
        // Use nil-coalescing to fall back to empty strings if keys are missing
        self.articleID = rawData["_id"] as? String ?? ""
        self.nameChinese = rawData["A_Name_Ch"] as? String ?? ""
        self.location = rawData["A_Location"] as? String ?? ""
        self.nameEnglish = rawData["A_Name_En"] as? String ?? ""
        self.cid = rawData["A_CID"] as? String ?? ""
        
        // Pull the parsed lng/lat values
        self.longitude = rawData["lng"] as? Double
        self.latitude = rawData["lat"] as? Double
    }
}

Quick notes #

• The helper function handles cases where A_Geo might be malformed (returns nil for both coords if parsing fails)—you can expand this to log errors or handle edge cases if needed.
• I swapped out try? for a do-catch block and added explicit error handling for missing data/invalid JSON structure—this makes it easier to debug if something goes wrong.
• The original JSON snippet you shared uses Chinese quotation marks (“”), but real JSON uses English ones (""), so the key names in the code are correct as-is.

内容的提问来源于stack exchange，提问作者Teddy Chen