Swift Json KeyNotFound - json

Question

Please help make this work I've been trying to figure out JSON and Swift for a week and facing this problem for 5 hours so far today.
Error Received
ERROR WHEN DECODING JSON keyNotFound(CodingKeys(stringValue: "MP", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: "MP", intValue: nil) ("MP").", underlyingError: nil))
YEAR IS NIL
Code
struct UserDay: Codable {
let MP: UserMP
let WP: UserWP
}
struct UserMP: Codable {
let M: [UserM]
let S: [UserS]
}
struct UserM : Codable {
let title: String
let description: String
let time: String
}
struct UserS : Codable {
let title: String
let description: String
let time: String
}
struct UserWP: Codable {
let WP: [WPData]
}
struct WPData: Codable {
let title: String
let values: [Int]
}
class LogDataHandler {
public func grabJSONInfo(){
guard let jsonURL = Bundle(for: type(of: self)).path(forResource: "newLogData", ofType: "json") else { return }
guard let jsonString = try? String(contentsOf: URL(fileURLWithPath: jsonURL), encoding: String.Encoding.utf8) else { return }
// print(jsonString)
// Print Info for TESTING
var year: UserDay?
do {
year = try JSONDecoder().decode(UserDay.self, from: Data(jsonString.utf8))
} catch {
print("ERROR WHEN DECODING JSON \(error)")
}
guard let results = year else {
print("YEAR IS NIL")
return
}
print(results)
}
}
JSON
{
"01/01/2020": {
"MP" : {
"M" : [
{"title" : "m1", "description" : "1", "time" : "12:30pm"},
{"title" : "m2", "description" : "2", "time" : "1:30pm"},
{"title" : "m3", "description" : "3", "time" : "2:30pm"}
],
"S" : [
{"title" : "s1", "description" : "1", "time" : "1pm"}
]
},
"WP" : [
{ "title" : "abc", "values" : [12, 10, 6]},
{ "title" : "def", "values" : [8]}
]
},
"01/29/2020": {
"MP" : {
"M" : [{"title" : "m1", "description" : "1", "time" : "12:30pm"}],
"S" : [{"title" : "s1", "description" : "1", "time" : "12:30pm"}]
},
"WP" :[{ "title" : "def", "values" : [8]}]
}
}

Answer 1

First, replace let WP: UserWP with an array:
struct UserDay: Codable {
let MP: UserMP
let WP: [WPData]
}
Then decode [String:UserDay] instead of UserDay:
try JSONDecoder().decode([String:UserDay].self, from: Data(jsonString.utf8))
Note that this will return a dict with key-value pairs "01/01/2020":UserDay object.
This means you can't assign a dictionary [String: UserDay] to a UserDay variable. Instead you can access the dict by a key which is some date (eg. "01/01/2020") and then assign it to your UserDay variable:
let result = try JSONDecoder().decode([String:UserDay].self, from: Data(jsonString.utf8))
let someYear = result["01/01/2020"]
Note that someYear will be optional so you may want to provide a default value or force-unwrap it.