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iOS Error Handling in Swift Error Handling Handling Errors

Gokul Nishanth
Gokul Nishanth
245 Points

How to get all the keys from the dictionary?

I have used this syntax:

let allKeys = Array(data.keys)

error.swift
enum ParserError: Error {
  case emptyDictionary
  case invalidKey
}

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

  func parse() throws {
      guard let nilData = data?["someKey"] else {
        throw ParserError.emptyDictionary
      }

      let keysArray = Array(data.keys) 

      guard let key = keysArray.contains("someKey") else {
        throw ParserError.invalidKey
      }
  }
}

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

1 Answer

Hey man, I found this one daunting at first, but this is how I ultimately got it to work:

enum ParserError: Error { case emptyDictionary case invalidKey }

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

func parse() throws {
    guard data != nil else {
        throw ParserError.emptyDictionary
    }
    guard (data?["someKey"]) != nil else {
        throw ParserError.invalidKey
    }
}

}

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

do { let someData = try parser.parse() } catch ParserError.emptyDictionary { print("I'm so empty inside") } catch ParserError.invalidKey { print("I'm also an invalid") }