How to call dataTask method several times with a counter? - swift

Question

I'm currently developing an application using SwiftUI.
I want to call dataTask method several times with while method, a flag, and a counter.
But my code doesn't work...
How could solve this problem?
Here is my code:
func makeCallWithCounter(){
var counter = 0
var flag = false
// Set up the URL request
let endpoint: String = "https://sample.com/api/info/"
guard let url = URL(string: endpoint) else {
print("Error: cannot create URL")
return
}
var urlRequest = URLRequest(url: url)
// set up the session
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)
// make the request
let task = session.dataTask(with: urlRequest) {
(data, response, error) in
// parse the result as JSON, since that's what the API provides
DispatchQueue.main.async {
do{ self.sample = try JSONDecoder().decode([Sample].self, from: responseData)
counter += 1
if counter > 4 {
flag = true
}
}catch{
print("Error: did not decode")
return
}
}
}
while flag == false {
task.resume()
}
}
UPDATED
func makeCallWithCounter(){
var day = 1
var date = "2020-22-\(day)"
var totalTemperature = 0
var counter = 0
var flag = false
// Set up the URL request
let endpoint: String = "https://sample.com/api/info/?date=\(date)"
guard let url = URL(string: endpoint) else {
print("Error: cannot create URL")
return
}
var urlRequest = URLRequest(url: url)
// set up the session
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)
// make the request
let task = session.dataTask(with: urlRequest) {
(data, response, error) in
// parse the result as JSON, since that's what the API provides
DispatchQueue.main.async {
do{ self.sample = try JSONDecoder().decode([Sample].self, from: responseData)
day += 1
totalTemperature += self.sample.temperature
if day > 4 {
flag = true
}
}catch{
print("Error: did not decode")
return
}
}
}
while flag == false {
task.resume()
}
print(totalTemperature)
}
Xcode:Version 12.0.1

Answer 1

As I wrote in the comments you need a loop and DispatchGroup. On the other hand you don't need flag and counter and actually not even the URLRequest
I removed the redundant code and there is still a serious error: The line
totalTemperature += sample.temperature
cannot work if sample is an array. The question contains not enough information to be able to fix that.
func makeCallWithCounter() {
var totalTemperature = 0
let group = DispatchGroup()
for day in 1...4 {
// Set up the URL request
let endpoint = "https://sample.com/api/info/?date=2020-22-\(day)"
guard let url = URL(string: endpoint) else {
print("Error: cannot create URL")
continue
}
// make the request
group.enter()
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
defer { group.leave() }
if let error = error { print(error); return }
// parse the result as JSON, since that's what the API provides
do {
let sample = try JSONDecoder().decode([Sample].self, from: data!)
totalTemperature += sample.temperature
} catch {
print(error)
}
}
task.resume()
}
group.notify(queue: .main) {
print(totalTemperature)
}
}