Swift: Optional Text In Optional Value

Question

How to remove Optional("") text on optional value when displaying without forcing to !.

Update

// I have somthing like this declared outside class
// I put question mark wrapper since I don't know when this session might have a value
var url = "\(self.session?.apiURL)/api/products.json"

// private session
private var _session:Session?

class MyClass
{
   .
   .
   .


   // the value of apiURL depends on session, session has optional value and declared as
   // custom lazy loaded var session
   var session:Session?
   {
      get
      {  
         if _session == nil 
         {
           _session = // fetch from coredata store if there is an active session. Might return nil

           // if no active session
           if _session == nil
           {
              // I just print "No active session"
           }
         }

         // return _session may or may not contain any value
         return _session
      }
   }
}

When the session has a value the url has a value:

Optional("my_api_url_here")/api/products.json

some example code? and you can't override/swizzle `description` for `Optional` — Bryan Chen, Sep 11 '14 at 05:04

Thanh Pham · Answer 1 · 2016-05-27T11:18:08.450

You can use this pod http://cocoapods.org/pods/NoOptionalInterpolation.

Alternatively, add this code to your project to remove the Optional(...) and nil text in string interpolation:

public protocol Unwrappable {
    func unwrap() -> Any?
}

extension Optional: Unwrappable {
    public func unwrap() -> Any? {
        switch self {
        case .None:
            return nil
        case .Some(let unwrappable as Unwrappable):
            return unwrappable.unwrap()
        case .Some (let some):
            return some
        }
    }
}

public extension String {
    init(stringInterpolationSegment expr: Unwrappable) {
        self = String(expr.unwrap() ?? "")
    }
}

Please note that simply overriding the description function of Optional won't work for string interpolation, although it works for print.

Awesome solution here, and it helped me improve my own custom operator to handle nested optionals perfectly. For those who don't wish to override the default functionality, consider [my own answer here](http://stackoverflow.com/a/37843344/994104). — Jeremy, Jun 15 '16 at 18:51

score 3 · Accepted Answer · answered Sep 11 '14 at 05:37

3

you can use ?? (null coalescing operator) to unwrap it and provide a default value if it is nil

let sessionApiURL = self.session?.apiURL ?? ""
var url = "\(sessionApiURL)/api/products.json"

answered Sep 11 '14 at 05:37

Bryan Chen

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Note that this only works well when working with optionals of type `String?`. You won't be able to do something like: `let i: Int? = 88; let s = i ?? "nil"` – Jeremy Jun 15 '16 at 18:16

score 0 · Answer 3 · answered Apr 02 '18 at 11:29

If you want to without optional value you have to unwrap the Optional. You can use "optional binding" to unwrap an Optional:

if let url = self.session?.apiURL{
     //you can use url without optional
     print(url)
}

You can check my example in online swift playground for better understand.

Swift: Optional Text In Optional Value

3 Answers3

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