Decode PropertyList using Swift 4 Codable PropertyListDecoder()

Question

Im trying to decode a plist using PropertyListDecoder() but when I get to the trying to access the keys, I get an error that says it's in the wrong format. I'm at a loss on what I'm doing wrong. Im under the assumption I can decode a Plist file the same way I can decode a JSON file right? I don't know, I'm still new to this.

//struct for PLists
struct AccessControl: Decodable {
    enum AccessControlKeys: String, CodingKey {
         case api
     }

    enum KeySecretKeys: String, CodingKey {
        case apiKey = "KEY"
        case apiSecret = "SECRET"
    }

    var KEYS: [KeySecrets]
//custom decoder
    init(from decoder: Decoder) throws {
        let accessContainer = try decoder.container(keyedBy: AccessControlKeys.self)
        let nestedContainer = try accessContainer.nestedContainer(keyedBy: KeySecretKeys.self, forKey: .api)
        self.KEYS = try nestedContainer([KeySecrets].self, forKey: .apiKey)
        self.KEYS = try nestedContainer.decode([KeySecrets].self, forKey: .apiSecret)
    }
}

struct KeySecrets: Decodable {
    var apiKey: String
    var apiSecret: String
}



func provideAccessKeys(for api: apis = .api, mode: modes = .dev) -> keysForApi? {
    switch api {
    case .api:
        print("Api")
    }
    switch mode {
    case .dev:
        print("mode - developers")
    case .test:
        print("mode - test")
    case .prod:
        print("mode - production")
    }
}

This was my first approach at it, but it would throw an error saying

'The data couldn't be read because it was the wrong format'

if let fileURL = Bundle.main.url(forResource: "Accesscontrol",   withExtension: "plist") {
    do {
        let data = try Data.init(contentsOf: fileURL, options: .mappedIfSafe)
        let decoder = PropertyListDecoder()
        let result = try decoder.decode(AccessControl.self, from: data)

    } catch {
        print(error.localizedDescription)
    }
}

Second approach, kinda just abandoned Codable all together, still couldn't pull out the values

guard let fileUrl = Bundle.main.url(forResource: "Accesscontrol", withExtension: "plist") else {return}
let key: String
let secret: String
do {
    let data = try Data.init(contentsOf: fileUrl, options: .mappedIfSafe)
    let plist = try! PropertyListSerialization.propertyList(from:data, options: [], format: nil) as! [Any]
  print(plist)
   let dictionary = plist[api.rawValue]

} catch {
    print(error.localizedDescription)
}

The plist file is structured like

<plist version="1.0">
<dict>
    <key>A_GROUP_OF_KEYS</key>
    <array>
        <dict>
            <key>KEY1</key>
            <string>KEY1_STRING</string>
            <key>SECRET1_KEY</key>
            <string>SECRET1_STRING</string>
        </dict>
        <dict>
        <key>KEY2</key>
        <string>KEY2_STRING</string>
        <key>SECRET2_KEY</key>
        <string>SECRET2_VALUE</string>
        </dict>
        <dict>
        <key>KEY</key>
        <string>KEY_STRING</string>
        <key>SECRET_KEY</key>
        <string>SECRET_VALUE</string>
        </dict>
    </array>
<key>ANOTHER_GROUP_OF_KEYS</key>
    <array>
        <dict>
            <key>KEY1</key>
            <string>KEY1_STRING</string>
            <key>SECRET1_KEY</key>
            <string>SECRET1_STRING</string>
        </dict>
        <dict>
        <key>KEY2</key>
        <string>KEY2_STRING</string>
        <key>SECRET2_KEY</key>
        <string>SECRET2_VALUE</string>
        </dict>
        <dict>
        <key>KEY</key>
        <string>KEY_STRING</string>
        <key>SECRET_KEY</key>
        <string>SECRET_VALUE</string>
        </dict>
    </array>
</dict>
</plist>

Any advice?

Answer 1

Your plist file was badly formatted and hence undecodable. You shouldn't name every key with a different key name like KEY1 , KEY2 , KEY3 , etc. Instead, you should use one name for the key key and put the actual name in the value field. The same goes for secret .

Here's a better plist file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>A_GROUP_OF_KEYS</key>
    <array>
        <dict>
            <key>key</key>
            <string>KEY1_STRING</string>
            <key>secret</key>
            <string>SECRET1_STRING</string>
        </dict>
        <dict>
            <key>key</key>
            <string>KEY2_STRING</string>
            <key>secret</key>
            <string>SECRET2_VALUE</string>
        </dict>
        <dict>
            <key>key</key>
            <string>KEY3_STRING</string>
            <key>secret</key>
            <string>SECRET3_VALUE</string>
        </dict>
    </array>
    <key>ANOTHER_GROUP_OF_KEYS</key>
    <array>
        <dict>
            <key>key</key>
            <string>KEY1_STRING</string>
            <key>secret</key>
            <string>SECRET1_STRING</string>
        </dict>
        <dict>
            <key>key</key>
            <string>KEY2_STRING</string>
            <key>secret</key>
            <string>SECRET2_VALUE</string>
        </dict>
        <dict>
            <key>key</key>
            <string>KEY3_STRING</string>
            <key>secret</key>
            <string>SECRET3_VALUE</string>
        </dict>
    </array>
</dict>
</plist>

Decoding this is dead simple:

struct AccessControl: Decodable {
    struct Key: Decodable {
        var key: String
        var secret: String
    }

    var keyGroup1: [Key]
    var keyGroup2: [Key]

    enum CodingKeys: String, CodingKey {
        case keyGroup1 = "A_GROUP_OF_KEYS"
        case keyGroup2 = "ANOTHER_GROUP_OF_KEYS"
    }
}