DecodingError.swift

DecodingError.swift

// instead of "nested" try catches...

public func load() async throws -> [FeedItem] {
    do {
        let (data, response) = try await client.get(from: url)
        guard let httpResponse = response as? HTTPURLResponse else {
            throw Error.invalidData
        }
        
        guard httpResponse.statusCode == 200 else {
            throw NetworkError.badStatus(httpResponse.statusCode)
        }
        
        do {
            let decoder = JSONDecoder()
            let items = try decoder.decode([FeedItem].self, from: data)
            return items
        } catch {
            throw Error.invalidData
        }
    } catch {
        throw Error.connectivity
    }
}

// do

public func load() async throws -> [FeedItem] {
    do {
        let (data, response) = try await client.get(from: url)
        guard let httpResponse = response as? HTTPURLResponse else {
            throw Error.invalidData
        }
      
        guard httpResponse.statusCode == 200 else {
            throw NetworkError.badStatus(httpResponse.statusCode)
        }
      
        return try JSONDecoder().decode([FeedItem].self, from: data)
    } catch is DecodingError {
        throw Error.invalidData
    } catch {
        throw Error.connectivity
    }
}

// no nesting or messy switch statements needed

// also a better onSuccess/failure handler

extension Result {
    func onSuccess(_ handler: (Success) -> Void, failure: (Failure) -> Void) -> Self {
        switch self {
        case .success(let value):
            handler(value)
        case .failure(let error):
            failure(error)
        }
        return self
    }
}