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iOS Error Handling in Swift 2.0 Error Handling Handling Errors

How to check if Dictionary is nil

I know I can use a guard let statement to check whether or not a key exists, but I dont remember a lesson on how to check whether or not an entire dictionary contains data? Maybe something like [key : value] ????

enum ParserError: ErrorType {
  case EmptyDictionary
  case InvalidKey

struct Parser {
  var data: [String : String?]?

  func parse() throws {
  if let data = [nil : nil] { throw ParserError.EmptyDictionary }
 guard let key = data["someKey"] else { throw ParserError.InvalidKey } 


let data: [String : String?]? = ["someKey": nil]
let parser = Parser(data: data)

1 Answer

Jari Koopman
.a{fill-rule:evenodd;}techdegree seal-36
Jari Koopman
Python Web Development Techdegree Graduate 29,349 Points

Hi Elijah,

If you want to get what I think you want to get (just checking if there's anything in the dictionary) you can just use the not operator like this:

var dict: [String: AnyObject]
if dict != nil {
 //Now you know it's not nil, so it contains someting

Hope this helped!

Kind regards, Jari