如果有人正在寻找SwiftyJSON答案: 更新: 对于Swift 3/4:

if let path = Bundle.main.path(forResource: "assets/test", ofType: "json") {
    do {
        let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .alwaysMapped)
        let jsonObj = try JSON(data: data)
        print("jsonData:\(jsonObj)")
    } catch let error {
        print("parse error: \(error.localizedDescription)")
    }
} else {
    print("Invalid filename/path.")
}

我可能还会推荐Ray Wenderlich的Swift JSON教程(它还涵盖了很棒的SwiftyJSON替代品，Gloss)。一段摘录(它本身并不能完全回答海报上的问题，但这个答案的附加价值是链接，所以请不要给它加-1):

在Objective-C中，解析和反序列化JSON相当简单:

NSArray *json = [NSJSONSerialization JSONObjectWithData:JSONData
options:kNilOptions error:nil];
NSString *age = json[0][@"person"][@"age"];
NSLog(@"Dani's age is %@", age);

在Swift中，由于Swift的可选选项和类型安全，解析和反序列化JSON有点繁琐，但作为Swift 2.0的一部分，guard语句被引入，以帮助摆脱嵌套的if语句:

var json: Array!
do {
  json = try NSJSONSerialization.JSONObjectWithData(JSONData, options: NSJSONReadingOptions()) as? Array
} catch {
  print(error)
}

guard let item = json[0] as? [String: AnyObject],
  let person = item["person"] as? [String: AnyObject],
  let age = person["age"] as? Int else {
    return;
}
print("Dani's age is \(age)")

当然，在XCode 8中。x，你只需双击空格键，然后说“嘿，Siri，请在Swift 3.0中用空格/制表符缩进为我反序列化这个JSON。”

最新的swift 3.0绝对有效

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

//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。

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
}