Swift中经常会遇到字典和字符串的相互转换，因此可以转换可以封装起来，转换代码如下:

func convertStringToDictionary(text: String) -> [String:AnyObject]? {
    if let data = text.data(using: String.Encoding.utf8) {
        do {
            return try JSONSerialization.jsonObject(with: data, options: [JSONSerialization.ReadingOptions.init(rawValue: 0)]) as? [String:AnyObject]
        } catch let error as NSError {
            print(error)
        }
    }
    return nil
}


func convertDictionaryToString(dict:[String:AnyObject]) -> String {
    var result:String = ""
    do {
        //如果设置options为JSONSerialization.WritingOptions.prettyPrinted，则打印格式更好阅读
        let jsonData = try JSONSerialization.data(withJSONObject: dict, options: JSONSerialization.WritingOptions.init(rawValue: 0))

        if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {
            result = JSONString
        }
        
    } catch {
        result = ""
    }
    return result
}

func convertArrayToString(arr:[AnyObject]) -> String {
    var result:String = ""
    do {
        let jsonData = try JSONSerialization.data(withJSONObject: arr, options: JSONSerialization.WritingOptions.init(rawValue: 0))
        
        if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {
            result = JSONString
        }
        
    } catch {
        result = ""
    }
    return result
}

Swift字典转字符串扩展:

extension Dictionary where Key: ExpressibleByStringLiteral, Value:AnyObject {
    
    var jsonString:String {
        do {
            let stringData = try JSONSerialization.data(withJSONObject: self as NSDictionary, options: JSONSerialization.WritingOptions.prettyPrinted)
            if let string = String(data: stringData, encoding: String.Encoding.utf8){
                return string
            }
        } catch _ {
            
        }
        return ""
    }
}

实际测试:

    let jsonText:String = "{\"order_info\":[{\"order_id\":\"1479828084819597144\",\"channel\":\"ios\",\"product_id\":\"02\"},{\"order_id\":\"1479828084819597144\",\"channel\":\"ios\",\"product_id\":\"02\"}]}"
    
    let dict = self.convertStringToDictionary(text: jsonText)
    print("字符串转换之后的字典:\(dict!)")
    
    
    var dictionaryOrArray : [String: AnyObject] = [:]
    dictionaryOrArray["a\"b"] = "cd" as AnyObject?
    dictionaryOrArray["strings"] = ["string", "another"] as AnyObject?
    dictionaryOrArray["keywdict"] = [ "anotherKey": 100, "Key2": "Val2"] as AnyObject?
    dictionaryOrArray["numbers"] = [ 1, 2, 3] as AnyObject?
    dictionaryOrArray["bools"] = [ true, false] as AnyObject?
    let convertResult:String = self.convertDictionaryToString(dict: dictionaryOrArray)
    print("字典转换之后的字符串:\(convertResult)")
    
    
    let array:[String] = ["FlyElephant","keso"]
    print("数组转换之后的数组:\(self.convertArrayToString(arr: array as [AnyObject]))")