Question

我已经花了好几个小时从应用包中的JSON文件中读取值并打印这些值。我一直在搜索几个论坛和SO问题试图拼凑一个从.json文件中读取的方法，但没有运气。我目前拥有的是一堆（可能无用的）代码，如下所示：

//json parsing
        if let path = Bundle.main.path(forResource: "POIs", ofType: "json") {
            do {
                let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .mappedIfSafe)
                let jsonResult = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves)
                if let jsonResult = jsonResult as? Dictionary<String, AnyObject>, let pois = jsonResult["POI"] {

                    print("test ", pois)
                    for poi in pois as! [AnyObject] {
                        guard let name = poi["name"], //String
                            let coordinatesJSON = poi["coordinates"] as? [String: Double],
                            let latitudeVar = coordinatesJSON["lat"],
                            let longitudeVar = coordinatesJSON["lng"],
                            let altitude = poi["altitude"], //Int
                            let facebookurl = poi["facebookurl"], //String
                            let poiImage = poi["pinImage"] //String
                        else {
                            return
                        }

我的POIs.json文件如下所示：

{
"POI":[
        {
            "name": "Boston Paintball",
            "coordinates": {
                "lat": 42.401848,
                "lng": -71.023843
            },
            "altitude": 7,
            "facebookurl": "https://www.facebook.com/PlayBostonPaintball/",
            "pinImage": "bp"
        },
        {
            "name": "Chilis",
            "coordinates": {
                "lat": 42.402314,
                "lng": -71.021655
            },
            "altitude": 7,
            "facebookurl": "https://www.facebook.com/chilis",
            "pinImage": "chilis"
        }
    ]
}

有人能告诉我从json读取值的最佳方法，将它们存储到我指定的变量中，然后打印出来吗？谢谢！

更新代码：

//json parsing
        let file = Bundle.main.url(forResource: "POIs", withExtension: "json")
        let data = try? Data(contentsOf: file!)
        let root = try? JSONDecoder().decode(Root.self, from: data!)

        do {
            let root = try JSONDecoder().decode(Root.self, from: data!)
            print(root)
        } catch {
            print(error)
        }

        let decoder = JSONDecoder()
        let pois = try? decoder.decode([Root].self, from: data!)

        let pinUIImage = UIImage(named: Location.pinImage)

但仍然给我Instance member 'pinImage' cannot be used on type 'ViewController.Location'错误。

更新2：

for poi in (root?.pointsOfInterest)! {
            if let location = root?.pointsOfInterest.??? { //I dont know how to grab the poi from the current iteration. Any tips?

Answer 1

您应该构建数据以符合Codable协议：

struct Root: Codable {
    let pointsOfInterest: [Location]
    private enum CodingKeys: String, CodingKey {
        case pointsOfInterest = "POI"
    }
}
struct Location: Codable {
    let name: String
    let coordinates: Coordinate
    let altitude: Int
    let facebookurl: String
    let pinImage: String
}
struct Coordinate: Codable {
    let latitude: Double
    let longitude: Double
    private enum CodingKeys: String, CodingKey {
        case latitude = "lat", longitude = "lng"
    }
}

do {
    let root = try JSONDecoder().decode(Root.self, from: jsonData)
    print(root)
} catch {
    print(error)
}

这将打印

Root（pointsOfInterest：[__ lldb_expr_39.Location（名称：“波士顿） Paintball“，坐标：__ lldb_expr_39.Coordinate（纬度： 42.401848000000001，经度：-71.023842999999999），海拔高度：7，facebookurl：“https://www.facebook.com/PlayBostonPaintball/”， pinImage：“bp”），__ lldb_expr_39。位置（名称：“Chilis”，坐标： __lldb_expr_39.Coordinate（北纬：42.402313999999997，经度：-71.021654999999996），海拔高度：7，facebookurl：“https://www.facebook.com/chilis”，pinImage：“chilis”）]）

将JSON文件中的值存储到变量中

1 个答案: