Use data on JSON with cells - ios

Question

I've got this JSON from an API:
{
"oldest": "2019-01-24T00:00:00+00:00",
"activities": [
{
"message": "<strong>Henrik</strong> didn't resist a guilty pleasure at <strong>Starbucks</strong>.",
"amount": 2.5,
"userId": 2,
"timestamp": "2019-05-23T00:00:00+00:00"
},
{
"message": "<strong>You</strong> made a manual transfer.",
"amount": 10,
"userId": 1,
"timestamp": "2019-01-24T00:00:00+00:00"
}
]
}
It has a lote more activities. How can I access it and fill my cells with its data? So far I've got this code:
MainViewController:
struct Activities: Decodable {
var oldest: String
var activities: [Activity]
}
struct Activity: Decodable {
var message: String
var amount: Float
var userId: Int
var timestamp: String
}
class MainTableViewController: UITableViewController, UITableViewDataSourcePrefetching {
var activityList: [Activities] = []
var activity: [Activity] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.prefetchDataSource = self
let activitiesJSONURLString = "https://qapital-ios-testtask.herokuapp.com/activities?from=2016-05-23T00:00:00+00:00&to=2019-05-23T00:00:00+00:00"
guard let activitiesURL = URL(string: activitiesJSONURLString) else { return }
URLSession.shared.dataTask(with: activitiesURL) { (data, response, err) in
// perhaps check err
// also perhaps check response status 200 OK
guard let data = data else { return }
do {
// Activities
let activities = try JSONDecoder().decode(Activities.self, from: data)
} catch let jsonErr {
print("Error serializing json: ", jsonErr)
}
DispatchQueue.main.async {
self.tableView.reloadData()
}
}.resume()
}
// MARK: - Table view data source
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return activityList.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ActivityCell", for: indexPath) as! MainTableViewCell
return cell
}
// Prefetching
func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
// if indexPaths.contains(where: isLoadingCell) {
// viewModel.fetchModerators()
// }
}
}
But I think something is off. Or I have no clue on how to start. I could really use some help or any tips you can give me. Please and thank you!

Answer 1

First of all the naming of the structs is pretty confusing. Name the root object with something unrelated like Response or Root.
And we are going to decode the timestamps as Date
struct Root: Decodable {
var oldest: Date
var activities: [Activity]
}
struct Activity: Decodable {
var message: String
var amount: Float
var userId: Int
var timestamp: Date
}
Second of all as the data is received in all the conformance to UITableViewDataSourcePrefetching is pointless. Remove it and delete also the prefetchRowsAt method.
Declare only one data source array and name it activities
var activities = [Activity]()
and delete
var activityList: Activities!
In the completion handler of the data task decode Root and assign the activities array to the data source array
do {
// Activities
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
let result = try decoder.decode(Root.self, from: data)
self.activities = result.activities
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch {
print("Error serializing json: ", error)
}
The table view data source methods are
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return activities.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ActivityCell", for: indexPath) as! MainTableViewCell
let activity = activities[indexPath.row]
// assign the activity data to the UI for example
// cell.someLabel = activity.amount
return cell
}

Answer 2

Because you are using the activityList to determine the number of rows, I'm assuming that you want to use the data from activityList in order to populate your ActivityCells. That is, unless, you meant for activityList to be a single instance of Activities instead of an array of Activities, in which case you would likely use activityList.activities.count in order to determine the number of rows. In either case, lets just call the array of data you want to use to fill the cells activityList.
In this case, you should make sure to update activityList to the activities that you have fetched from the API. Once you have the activityList, you can then use reloadData which will trigger your table view delegate methods. In tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) you can then use activityList in order to update the dequeued cell.
Something like this might be what you want:
class MainTableViewController: UITableViewController, UITableViewDataSourcePrefetching {
var activityList: Activities!
var activity: [Activity] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.prefetchDataSource = self
let activitiesJSONURLString = "https://qapital-ios-testtask.herokuapp.com/activities?from=2016-05-23T00:00:00+00:00&to=2019-05-23T00:00:00+00:00"
guard let activitiesURL = URL(string: activitiesJSONURLString) else { return }
URLSession.shared.dataTask(with: activitiesURL) { (data, response, err) in
// perhaps check err
// also perhaps check response status 200 OK
guard let data = data else { return }
do {
// Activities
let activities = try JSONDecoder().decode(Activities.self, from: data)
self.activityList = activities
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch let jsonErr {
print("Error serializing json: ", jsonErr)
}
}.resume()
}
// MARK: - Table view data source
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return activityList.activities.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ActivityCell", for: indexPath) as! MainTableViewCell
if let activity = activityList?[indexPath.row] {
// UPDATE CELL ACCORDING TO activity
}
return cell
}
}