这个字符串为什么解析不出来呢

这个字符串为什么解析不出来呢

class Attachment: NSObject {
var type : String?
var subType : String?
var data: [String:Any]?

}

{\"type\":\"SYSTEM\",\"subType\":\"SYSTEM_TITLE_URL\",\"data\":\"{\\\"title\\\":\\\"View notification\\\",\\\"msg\\\":\\\"User100833 ID(100833) viewed your profile, drop a line to see if User100833 needs help.Get $0.1 if you reply to your customer within 1 minute\\\",\\\"url\\\":\\\"star://message/messageDetail?businessId=211215095623664950135157010094\\\",\\\"appAlertFlag\\\":true}\"}

Reproduce the supplied JSON and Attachment model with HandyJSON, starting from the deserialization entry point used for this model. Inspect the parsing result and any reported error or mismatch; done means the cause of the failed parse and the expected handling are documented or addressed.

Written by the indexing model from the issue text.