Get data from URL as separate function [duplicate] - ios

Question

This question already has answers here:
function with dataTask returning a value
(4 answers)
Closed 5 years ago.
I try to create function to get data from URL:
func getStringFromUrl(urlString: String) -> String {
if let requestURL = URL(string: urlString) {
let session = URLSession(configuration: URLSessionConfiguration.default)
let task = session.dataTask(with: requestURL, completionHandler: { (data, response, error) in
if let data = data {
do {
let str = String(data: data, encoding: String.Encoding.utf8)
return str
}
catch let error as NSError {
print ("error = \(error)")
}
}
else {
print ("error = \(error)")
}
})
task.resume()
}
}
But I got this error: unexpected non-void return value in void function
How can I create a separate function to get data from Url?

Answer 1

In your code you have:
let str = String(data: data, encoding: String.Encoding.utf8)
return str
Which is inside a closure block which is not defined to return anything. Because the function session.dataTask is an asynchronous task, it won't return straight away. You should use a completion block/closure to get the response when it returns. Also bear in mind that it might not return, so the string needs to be optional. See the code below.
func getStringFromUrl(urlString: String, completion: #escaping (_ str: String?) -> Void) {
if let requestURL = URL(string: urlString) {
let session = URLSession(configuration: URLSessionConfiguration.default)
let task = session.dataTask(with: requestURL, completionHandler: { (data, response, error) in
if let data = data {
do {
let str = String(data: data, encoding: String.Encoding.utf8)
completion(str)
}
catch let error as NSError {
print ("error = \(error)")
completion(nil)
}
}
else {
print ("error = \(error)")
completion(nil)
}
})
task.resume()
}
}
EDIT: Usage
getStringFromUrl(urlString: "http://google.com") { str in
if let text = str {
// you now have string returned
}
}