Issue sorting dynamic sections in tableview | Swift - swift

Question

How can I sort the following sections made dynamically from the datestamp field? For example the sections called 2021-11-3 needs to be displayed in the tableview above 2021-11-2
datestamp format: 2021-11-3
var sections = [mySections]()
var structure = [myStructure]()
private func fetchJSON() {
guard let url = URL(string: "test.com")
else { return }
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = "id=\1".data(using: .utf8)
URLSession.shared.dataTask(with: request) { data, _, error in
guard let data = data else { return }
do {
let decoder = JSONDecoder()
self.structure.sort { $0. datestamp > $1.datestamp }
let res = try decoder.decode([myStructure].self, from: data)
let grouped = Dictionary(grouping: res, by: { $0. datestamp })
let keys = grouped.keys.sorted()
self.sections = keys.map({mySections(date: $0, items: grouped[$0]!
)})
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
catch {
print(error)
}
}.resume()
}
I have tried doing the following under self.sections but it does not do anything:
self.sections.sorted { $0.date > $1.date }
Struct:
struct mySections {
let date : String
var items : [myStructure]
}
struct myStructure: Decodable {
let recordid: Int
let testname: Int
let datestamp: String
}
Example of Data:
[
{
"recordid": 1,
"testname": "Jen",
"datestamp": "2021-11-3"
},
{
"recordid": 1,
"testname": "Jake",
"datestamp": "2021-11-2"
}
]

Answer 1

Right now, you're sorting structure based on dateTimeStamp, which doesn't do anything, because structure doesn't have any data in it.
In my playground example, like your code, I used Dictionary(grouped:). Then, I map those results to mySections and sort by date.
The result of the print at the end is:
["2021-11-4", "2021-11-3", "2021-11-2"]
let data = """
[
{
"recordid": 1,
"testname": "Jake",
"datestamp": "2021-11-2"
},
{
"recordid": 2,
"testname": "Jen",
"datestamp": "2021-11-3"
},
{
"recordid": 3,
"testname": "Bob",
"datestamp": "2021-11-3"
},
{
"recordid": 4,
"testname": "Bill",
"datestamp": "2021-11-4"
}
]
""".data(using: .utf8)!
struct mySections {
let date : String
var items : [myStructure]
}
struct myStructure: Decodable {
let recordid: Int
let testname: String
let datestamp: String
}
var sections = [mySections]()
var structure = [myStructure]()
do {
let decoder = JSONDecoder()
let res = try decoder.decode([myStructure].self, from: data)
let grouped = Dictionary(grouping: res, by: { $0.datestamp })
sections = grouped.map { mySections(date: $0.key, items: $0.value) }
.sorted { $0.date > $1.date }
print(sections.map(\.date))
} catch {
print(error)
}
It's probably worth noting that right now your dates are stored in a uniform format that works well for string-based sorting. However, if your endpoint returned dates that weren't uniformly-formatted (like 2021-11-04 and 2021-11-3) you would want to convert to an actual Date first and sort based on that.