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iOS Error Handling in Swift Error Handling Handling Errors

Posted by kasaltrix
kasaltrix
9,491 Points

Please help me with this error handling code

I have completed the challenge but I am trying to take it one step further. I am trying to check whether the value for a key in the dictionary is nil or not using the second guard statement, but it doesn't work as expected. According to the code, it should throw an invalidKey error but it doesn't. I don't know what am I doing wrong. Any help would be quite useful!!!

error.swift 
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{
    try parser.parse()
}
catch ParserError.emptyDictionary{
    print("Empty Dictionary")
}
catch ParserError.invalidKey{
    print("No valid data")
}

2 Answers

Dhanish Gajjar
Dhanish Gajjar
20,185 Points
Dhanish Gajjar
Dhanish Gajjar
20,185 Points

The implementation of the parse function is much simpler ! This should work !

enum ParserError: Error {
    case emptyDictionary
    case invalidKey
}

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

    func parse() throws {
        guard let data = data else {
            throw ParserError.emptyDictionary
        }

        guard let _ = data["someKey"] else {
            throw ParserError.invalidKey
        }
    }
}

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

do {
    try parser.parse()
} catch ParserError.emptyDictionary {
    print("Nil Data")
} catch ParserError.invalidKey {
    print("Invalid Key")
}
kasaltrix
kasaltrix
9,491 Points

Thanks for the reply Dhanish, but this is not what I asked for. As I wrote in my question, I have already completed the challenge and the code that you have provided is for completing the challenge. My question was how to check whether the value passed to someKey is nil or not using the guard condition. If you have know the answer to this, please reply back. Once again thank you for your time :)

Angus Muller
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Angus Muller
iOS Development Techdegree Graduate 12,473 Points
Angus Muller
.a{fill-rule:evenodd;}techdegree seal-36
Angus Muller
iOS Development Techdegree Graduate 12,473 Points

Hi kasaltrix did you ever find your answer?I have written code that passes the task but I find it won't print nil data when there is nil. Gus