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iOS Error Handling in Swift Error Handling Handling Errors

Posted by Nagaraju Banoth
Nagaraju Banoth
Courses Plus Student 5,617 Points

How to solve Challenge Task 3 of 3 in Error Handling in Swift 3?

Challenge Task 3 of 3

Perfect! We're almost done. Rather than a generic catch clause, let's pattern match on the specific errors so that we can log better error messages. In this task, change the catch statement to include specific error cases. Like before you can just log an error message of your choosing.

error.swift 
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 key = data["somekey"] else {
            throw ParserError.InvalidKey
        }

    }
}

let data: [String : String?]? = ["someKey": nil]
do {
    let parser = try Parser(data: data)
    try parser.parse()
} catch ParserError.EmptyDictionary {
print("error")
}
catch
    ParserError.InvalidKey {
print("errorr")
}
Raed Alahmari
Raed Alahmari
12,966 Points
Raed Alahmari
Raed Alahmari
12,966 Points 
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 data["somekey"] != nil else {
            throw ParserError.invalidKey
        }
    }
}

let data: [String : String?]? = ["somekey": nil]

do {
    let parser = try Parser(data: data)
    try parser.parse()
} catch ParserError.emptyDictionary(let description) {
    print(description)
}
catch ParserError.invalidKey(let description) {
    print(description)
}