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iOS Error Handling in Swift Error Handling Handling Errors

Gokul Nishanth
Gokul Nishanth
245 Points
Posted by 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

Elliot Rutherfoord
Elliot Rutherfoord
7,684 Points

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") }