对于那些希望在decodedable抛出错误后在调试器/ lldb中打印JSON数据的人，请尝试以下方法。

阿宝试试!JSONSerialization。jsonObject(:数据!，选项:.mutableLeaves) as?字典<字符串,任何>

斯威夫特4。X和5。x使用可解码

struct ResponseData: Decodable {
    var person: [Person]
}
struct Person : Decodable {
    var name: String
    var age: String
    var employed: String
}

func loadJson(filename fileName: String) -> [Person]? {
    if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
        do {
            let data = try Data(contentsOf: url)
            let decoder = JSONDecoder()
            let jsonData = try decoder.decode(ResponseData.self, from: data)
            return jsonData.person
        } catch {
            print("error:\(error)")
        }
    }
    return nil
}

斯威夫特3

func loadJson(filename fileName: String) -> [String: AnyObject]? {
    if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
        do {
            let data = try Data(contentsOf: url)
            let object = try JSONSerialization.jsonObject(with: data, options: .allowFragments)
            if let dictionary = object as? [String: AnyObject] {
                return dictionary
            }
        } catch {
            print("Error!! Unable to parse  \(fileName).json")
        }
    }
    return nil
}

Xcode 8 Swift 3读取json文件更新:

    if let path = Bundle.main.path(forResource: "userDatabseFakeData", ofType: "json") {
        do {
            let jsonData = try NSData(contentsOfFile: path, options: NSData.ReadingOptions.mappedIfSafe)
            do {
                let jsonResult: NSDictionary = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
                if let people : [NSDictionary] = jsonResult["person"] as? [NSDictionary] {
                    for person: NSDictionary in people {
                        for (name,value) in person {
                            print("\(name) , \(value)")
                        }
                    }
                }
            } catch {}
        } catch {}
    }

Swift 5.1, Xcode 11

你可以用这个:

struct Person : Codable {
    let name: String
    let lastName: String
    let age: Int
}

func loadJson(fileName: String) -> Person? {
   let decoder = JSONDecoder()
   guard
        let url = Bundle.main.url(forResource: fileName, withExtension: "json"),
        let data = try? Data(contentsOf: url),
        let person = try? decoder.decode(Person.self, from: data)
   else {
        return nil
   }

   return person
}

//change type based on your struct and right JSON file

let quoteData: [DataType] =
    load("file.json")

func load<T: Decodable>(_ filename: String, as type: T.Type = T.self) -> T {
    let data: Data

    guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
        else {
            fatalError("Couldn't find \(filename) in main bundle.")
    }

    do {
        data = try Data(contentsOf: file)
    } catch {
        fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
    }

    do {
        let decoder = JSONDecoder()
        return try decoder.decode(T.self, from: data)
    } catch {
        fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
    }
}

我提供了另一个答案，因为这里没有一个答案是针对从测试包加载资源的。如果您正在使用一个输出JSON的远程服务，并且希望在不触及实际服务的情况下对解析结果进行单元测试，则可以获取一个或多个响应，并将它们放入项目中的Tests文件夹中的文件中。

func testCanReadTestJSONFile() {
    let path = NSBundle(forClass: ForecastIOAdapterTests.self).pathForResource("ForecastIOSample", ofType: "json")
    if let jsonData = NSData(contentsOfFile:path!) {
        let json = JSON(data: jsonData)
        if let currentTemperature = json["currently"]["temperature"].double {
            println("json: \(json)")
            XCTAssertGreaterThan(currentTemperature, 0)
        }
    }
}

这也使用了SwiftyJSON，但获得测试包和加载文件的核心逻辑是问题的答案。