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iOS Error Handling in Swift Error Handling Handling Errors

Mohamed Almulla
Mohamed Almulla
2,506 Points

How do I check if they key exist or is not nil?

I need help writing the guard statement for the key and I don't really understand the hint that we were given that much either. Would be great if someone can tell me what I'm missing. Thank you very much.

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

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

  func parse(from dict: [String: String]) throws -> Parser {
        guard let parse = dict["someKey"] else{
        throw ParserError.emptyDictionary 
    }

    guard let val = dict[keys] else {
        throw ParserError.invalidKey 
    }
  }
}

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

1 Answer

You do not need to create a new constant for this instead you can just check the values.

    func parse() throws {
        guard data?.isEmpty == false else {
            throw ParserError.emptyDictionary
        }

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

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