lomokat lomokat - 1 year ago 200
iOS Question

Swift: Does not conform to protocol NSCoding

I am trying to use the NSCoding protocol on a class I have written in swift, but cannot seem to figure out why the compiler complains that it "does not conform to protocol NSCoding" when I do implement the required methods:

class ServerInfo: NSObject, NSCoding {

var username = ""
var password = ""
var domain = ""
var location = ""
var serverFQDN = ""
var serverID = ""

override init() {


init(coder aDecoder: NSCoder!) {
self.username = aDecoder.decodeObjectForKey("username") as NSString
self.password = aDecoder.decodeObjectForKey("password") as NSString
self.domain = aDecoder.decodeObjectForKey("domain") as NSString
self.location = aDecoder.decodeObjectForKey("location") as NSString
self.serverFQDN = aDecoder.decodeObjectForKey("serverFQDN") as NSString
self.serverID = aDecoder.decodeObjectForKey("serverID") as NSString

func encodeWithCoder(_aCoder: NSCoder!) {
_aCoder.encodeObject(self.username, forKey: "username")
_aCoder.encodeObject(self.password, forKey: "password")
_aCoder.encodeObject(self.domain, forKey: "domain")
_aCoder.encodeObject(self.location, forKey: "location")
_aCoder.encodeObject(self.serverFQDN, forKey: "serverFQDN")
_aCoder.encodeObject(self.serverID, forKey: "serverID")


Is this a bug or am I just missing something?

Answer Source

As you can see in the detailed compiler messages in the Report navigator, your methods are not declared correctly:

error: type 'ServerInfo' does not conform to protocol 'NSCoding'
class ServerInfo: NSObject, NSCoding {
Foundation.NSCoding:2:32: note: protocol requires function 'encodeWithCoder' with type '(NSCoder) -> Void'
  @objc(encodeWithCoder:) func encodeWithCoder(aCoder: NSCoder)
note: candidate has non-matching type '(NSCoder!) -> ()'
    func encodeWithCoder(_aCoder: NSCoder!) {
Foundation.NSCoding:3:25: note: protocol requires initializer 'init(coder:)' with type '(coder: NSCoder)'
  @objc(initWithCoder:) init(coder aDecoder: NSCoder)
note: candidate has non-matching type '(coder: NSCoder!)'
    init(coder aDecoder: NSCoder!) {

(This may have changed between the beta releases.) In addition, the initWithCoder method has to be marked as required:

required init(coder aDecoder: NSCoder) {   }

func encodeWithCoder(_aCoder: NSCoder) {   }

In Swift 3 the required methods are

required init(coder aDecoder: NSCoder) {   }

func encode(with aCoder: NSCoder) {   }
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