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iOS Error Handling in Swift 2.0 Error Handling Handling Errors

error handling

swift_lint.swift:15:38: error: expected 'else' after 'guard' condition guard let someKey = dict["someKey"] { ^ swift_lint.swift:12:27: error: cannot subscript a value of type '[String : String]' with an index of type '[String : String?]?' guard let someData = dict[data] else { ^ swift_lint.swift:12:27: note: overloads for 'subscript' exist with these partially matching parameter lists: (DictionaryIndex), (Key), (Range), (Self.Index) guard let someData = dict[data] else {

enum ParserError: ErrorType {
  case EmptyDictionary
  case InvalidKey

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

  func parse(dict: [String:String]) throws {
 guard let someData = dict[data] else {
 throw ParserError.EmptyDictionary
 guard let someKey = dict["someKey"] {
 throw ParserError.InvalidKey
let data: [String : String?]? = ["someKey": nil]
let parser = Parser(data: data)