ios - Unified response/error handling in swift -

im wondering how tackle such problem:

i have application lets user log in username , password. application sends credentials api server , in response gets logged user data

in model defined user class

class user {  var id: string var firstname: string? var lastname: string? var email: string var permissions: string? var birthday: string? var subscription: string?   init(id: string, firstname: string?, lastname: string?, email: string, permissions: string?, birthday: string?, subscription: string?) {     self.id = id     self.firstname = firstname     self.lastname = lastname     self.email = email     self.permissions = permissions     self.birthday = birthday     self.subscription = subscription } 

then in class called apiconnector, have (using afnetworking):

func loginuser(mainaddress: string, additionaladdr: string, email: string, password: string, callback: (success: bool, data: user) -> void){      let fulladdress = mainaddress + additionaladdr     var parameters = ["email":email, "password":password]      manager.post( fulladdress,         parameters: parameters,         success: { (operation: afhttprequestoperation!,responseobject: anyobject!) in              let json = json(data: operation.responsedata)              //here have json user data             callback(success: true, data: ???)         },         failure: { (operation: afhttprequestoperation!,error: nserror!) in             let json = json(data: operation.responsedata)                //here have json error             callback(success: false, data: ???)     }) } 

right u can see have callback returning user in data field. there problem when error occures , should returning errortype, not user.

i thinking how unify response create

enum result<t, e> { case ok(t) case error(e) } 

and in ok case return user object. in case of error return errortype object - kinda cannot head around it.

could explain me how unified response type in case ?

(i placed question marks instead of type in code, cause thats question , have no solution atm)

i'd go optional , exchange success decorated nserror nice error messages. example this:

class user {} class serverresponseerror {     var error: nserror     var message: string {         {             switch(error.code) {                 case 500:                     return "server error"                 default:                     return "unknown error"             }         }     }     init(error: nserror) {         self.error = error     } }  func loginuser(callback: (user: user?, error: serverresponseerror?) -> void){     // went wrong on server     var error: nserror = nserror(domain: "", code: 500, userinfo: nil)     callback(user: nil, error: serverresponseerror(error:error)) }  loginuser { (user, error) -> void in     print(error.message) } 

you can decorate error object returned server , pass same way (with user nil). think it's bad practice return 200 , error object.