Error consuming REST API using swift on iOS - ios

Question

I'm new on iOS development, I was following this tutorial: https://grokswift.com/simple-rest-with-swift/ and I don't know why the following code always return "the placeholder" and I can't see errors on the console's output:
import Foundation
class Resolver{
func doSomething() -> String{
var result = "the placeholder"
print("inside doSomething")
let postEndpoint: String = "http://jsonplaceholder.typicode.com/posts/1"
guard let url = NSURL(string: postEndpoint) else {
print("Error: cannot create URL")
return "error here"
}
let urlRequest = NSURLRequest(URL: url)
let config = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: config)
print("another thing")
let task = session.dataTaskWithRequest(urlRequest, completionHandler: {
(data, response, error) in
guard let responseData = data else {
print("Error: did not receive data")
return
//return "error here"
}
print("hereeeeeee ############")
guard error == nil else {
print("error calling GET on /posts/1")
print(error)
return
//return "error here"
}
// parse the result as JSON, since that's what the API provides
let post: NSDictionary
do {
post = try NSJSONSerialization.JSONObjectWithData(responseData,
options: []) as! NSDictionary
} catch {
print("error trying to convert data to JSON")
return
//return "error here"
}
// now we have the post, let's just print it to prove we can access it
print("The post is: " + post.description)
result = post.description
// the post object is a dictionary
// so we just access the title using the "title" key
// so check for a title and print it if we have one
if let postTitle = post["title"] as? String {
print("The title is: " + postTitle)
}
})
task.resume()
return result
}
}
this is my info.plist:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CFBundleIdentifier</key>
<string></string>
<key>CFBundleExecutable</key>
<string></string>
<key>CFBundleInfoDictionaryVersion</key>
<string>6.0</string>
<key>LSApplicationCategoryType</key>
<string></string>
<key>CFBundleName</key>
<string></string>
<key>CFBundleDisplayName</key>
<string></string>
<key>CFBundleVersion</key>
<string></string>
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
<key>NSExceptionDomains</key>
<dict>
<key>httpbin.org</key>
<dict>
<key>NSThirdPartyExceptionAllowsInsecureHTTPLoads</key>
<true/>
</dict>
<key>jsonplaceholder.typicode.com </key>
<dict>
<key>NSThirdPartyExceptionAllowsInsecureHTTPLoads</key>
<true/>
</dict>
</dict>
</dict>
<key>CFBundleShortVersionString</key>
<string></string>
<key>CFBundleGetInfoString</key>
<string></string>
</dict>
</plist>
When I run the test I see this output:
Test Suite 'RestTest' started at 2016-03-03 15:38:49.364
Test Case '-[FoodTrackerTests.RestTest testResolver]' started.
inside doSomething
another thing
// I want to see the result: the placeholder
Test Case '-[FoodTrackerTests.RestTest testResolver]' passed (0.061 seconds).
Test Suite 'RestTest' passed at 2016-03-03 15:38:49.425.
Executed 1 test, with 0 failures (0 unexpected) in 0.061 (0.062) seconds
Test Suite 'Selected tests' passed at 2016-03-03 15:38:49.426.
Executed 1 test, with 0 failures (0 unexpected) in 0.061 (0.063) seconds
Why the result variable doesn't contains the post.description value?

Answer 1

As suggested in the comments, it looks like tests are completing before the HTTP call is returned (because the HTTP request is asynchronous) and thus you aren't seeing the results of the API call before the test run ends.
Have a look at XCAsyncTestCase and set up your tests to wait for the async callback instead.

Answer 2

The doSomething() method returns "the placeholder" value before the asynchronous call is finished. That's why you see it.