如何将swift Dictionary转换为NSDictionary

Question

我正在尝试将[String : String](一个Swift字典)转换NSDictionary为以后用于生成字符串的JSON库

var parcelDict = ["trackingNumber" : parcel.number,
                  "dstCountry" : parcel.countryCode];

if (parcel.postalService != nil) 
{
    parcelDict["postalService"] = parcel.postalService;
}

var errorPtr: NSErrorPointer
let dict: NSDictionary = parcelDict
var data = NSJSONSerialization.dataWithJSONObject(dict, options:0, error: errorPtr) as NSData

return NSString(data: data, encoding: NSUTF8StringEncoding)

但let dict: NSDictionary = parcelDict不起作用

let dict: NSDictionary = parcelDict as NSDictionary

var data = NSJSONSerialization.dataWithJSONObject(parcelDict as NSMutableDictionary, options:0, error: errorPtr) as NSData

所有这些例子都不起作用.它们会产生以下错误:

这样做的正确方法是什么？

更新:

有效的代码

var parcelDict = ["trackingNumber" : parcel.number!,
                  "dstCountry" : parcel.countryCode!];

if (parcel.postalService != nil) {
    parcelDict["postalService"] = parcel.postalService;
}

var jsonError : NSError?
let dict = parcelDict as NSDictionary
var data = NSJSONSerialization.dataWithJSONObject(dict, options:nil, error: &jsonError)
return NSString(data: data!, encoding: NSUTF8StringEncoding)!

Answer 1

你必须这样投:

let dict = parcelDict as NSDictionary

否则,在ex方法中使用Swift Dictionary和NSDictionary时,它们的处理方式几乎相同:

func test(dict: NSDictionary) {}

let dict = ["Test":1]
test(dict)

会完全正常工作.

更新后

如果将Dictionary值类型更改为非可选String,则错误将消失.

[String:String?] change to -> [String:String]

Answer 2

您可以使用这种简单的方法

let dictSwift = ["key1": "value1", "key1": value2]

let dictNSMutable = NSMutableDictionary(dictionary: dictSwift)

享受编码!