Safe synchronous server requests with Swift-CodePudding

With the following code im am trying to organise server calls synchronously:

func synchronousGetRequest(group: DispatchGroup, completion: @escaping ()-> ()) {
    guard var url = URL(string: "https://192.168.187.30:5001/") else {return}
    let session = URLSession.shared.dataTask(with: url) { _, _, _ in
        completion()
    }
    session.resume()
    group.wait()
}

func loopFunc() {
    
    let group = DispatchGroup()

    for _ in 1...5 {
        print("start request")
        group.enter()
        synchronousGetRequest(group: group) {
            print("request finished\n")
            group.leave()
        }
    }
}

DispatchQueue.global(qos: .background).async {
    loopFunc()
}

print("End of script")

But im not much familiar with threading on Swift and I know that blocking threads might not be a good practice. Is it safe to run this function in a production application as long it's placed on a background thread?

Output:

End of script
start request
request finished

start request
request finished

start request
request finished

start request
request finished

start request
request finished

Thanks in advance!

CodePudding user response：

Your approach is fine but a better way is async/await.

The loop is executed in order although the requests are asynchronous.

func synchronousGetRequest() async throws -> String  {
    let url = URL(string: "https://192.168.187.30:5001/")!
    for i in 1...5 {
        print("start request \(i)")
        let (_, _) = try await URLSession.shared.data(from: url)
        print("end request \(i)")
        
    }
    return "End of script"
}

Task.detached {
    do {
        let result = try await synchronousGetRequest()
        print(result)
    } catch {
        print(error)
    }
}

Output:

start request 1
end request 1
start request 2
end request 2
start request 3
end request 3
start request 4
end request 4
start request 5
end request 5
End of script