Unable to encode String for URL in Swift 3 - ios

Question

I used to develop iOS Apps using Objective-C. Now I have recently migrated to Swift. In my app, I have a button that opens MS Outlook App with the pre-filled Subject and Body.
I did a similar App in Objective-C and used the below code to Encode my String for URL.
NSString *emailSubject = #"Test Subject";
NSString *encodedSubject = [emailSubject stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLHostAllowedCharacterSet]];
Now I am unable to do the same in Swift 3. Below is the code that I tried.
var subjectText: String = "Test Subject"
var encodedSubject = subjectText.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
var stringURL: String = "ms-outlook://compose?subject=" + subjectText + "&body=TestingEmailNow"
// Convert the string to a URL.
var url = URL(string: stringURL)
// Open the app that responds to the URL scheme (should be Outlook).
UIApplication.shared.openURL(url!)
The error that I am getting is below.
fatal error: unexpectedly found nil while unwrapping an Optional value
2017-06-07 04:29:35.158030+0400 My App[1286:405793] fatal error: unexpectedly found nil while unwrapping an Optional value
I know that this error is coming due to the space in my Subject. I can say this because if I remove the space, I don't even have to encode it. It works directly. What am I doing wrong over here?

Answer 1

You made a simple mistake.
check your line
var stringURL: String = "ms-outlook://compose?subject=" + subjectText + "&body=TestingEmailNow"
you are using subjectText instead of encodedSubject
Complete code:
var subjectText: String = "Test Subject"
var encodedSubject = subjectText.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
if let encodedSubject = encodedSubject {
var stringURL: String = "ms-outlook://compose?subject=" + encodedSubject + "&body=TestingEmailNow"
// Convert the string to a URL.
var url = URL(string: stringURL)
if let url = url {
// Open the app that responds to the URL scheme (should be Outlook).
UIApplication.shared.openURL(url)
}
}

Answer 2

Variable used was the problem but I'd also suggest using URLComponents instead of building the URL as string.
var subjectText: String = "Test Subject"
var components = URLComponents()
components.scheme = "ms-outlook"
components.host = "compose"
components.queryItems = [
URLQueryItem(name: "subject", value: subjectText),
URLQueryItem(name: "body", value: "TestingEmailNow")
]
if let url = components.url {
UIApplication.shared.openURL(url)
}