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iOS Error Handling in Swift 2.0 Error Handling Handling Errors

Posted by Hemant Torsekar
Hemant Torsekar
167 Points

The process isn't making sense to me. I've tried several ways to throw errors, and I issues within Preview. No clue why.

enum ParserError: ErrorType {
  case EmptyDictionary
  case InvalidKey
}

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

  func parse() throws {

     guard let keys = try data?.keys {
        throw ParseError.InvalidKey("Invalid Key")     
     }

  }
}
let data: [String : String?]? = ["someKey": nil]
let parser = Parser(data: data)
error.swift 
enum ParserError: ErrorType {
  case EmptyDictionary
  case InvalidKey
}

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

  func parse() throws {

     guard let keys = try data?.keys {
        throw ParseError.InvalidKey("Invalid Key")     
     }

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

1 Answer

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

Here's the function, and the instructions do seem a bit misleading:

    func parse() throws {
        guard let data = data else {  //check to see if there's any data
            throw ParserError.EmptyDictionary
        }
        guard let key = data["someKey"] else {  //check to see if the specific key exists
            throw ParserError.InvalidKey
        }
    }

Here's the do...try:

do {
    try parser.parse()
} catch ParserError.EmptyDictionary {
    print("empty dictionary")
} catch ParserError.InvalidKey {
    print("invalid key")
}