JSON to AnyObject from a .json file

ResponseMocker.swift

import Foundation

/// Mocks network responses. Useful to be used with Unit/UI tests.
class ResponseMocker {
    
    /// Returns a mocked `JSON` object encapsulated in an `AnyObject`,
    /// representing a mocked endpoint response.
    ///
    /// - returns: A mocked `JSON` object encapsulated in an `AnyObject`,
    /// representing a Notice root endpoint response.
    class func mockedEndpoint() -> Data {
        return retrieveDataFrom(filename: "MockedEndpoint")!
    }
    
    /// Reads a `JSON` file using the name passed in as parameter, converts and
    /// returns it as `AnyObject` - if the file exists. Otherwise, or if any
    /// error during the conversion, returns nil.
    ///
    /// - parameter filename: the `JSON` filename to be read.
    ///
    /// - returns: A `JSON` object in `AnyObject` format - or nil if the file
    /// does not exist or if any error during the conversion.
    class func retrieveDataFrom(filename: String) -> Data? {
        
        // First, find the file.
        if let path = Bundle.main.path(forResource: filename, ofType: "json"),
            let data = NSData(contentsOfFile: path) {
            
            do {
                // Convert it to JSON data.
                let jsonData = try JSONSerialization.jsonObject(
                    with: data as Data,
                    options: .mutableContainers
                )
                
                // Convert it to Data.
                let data = try JSONSerialization.data(
                    withJSONObject: jsonData,
                    options: .prettyPrinted
                )
                
                // Return.
                return data
                
            } catch {
                print("Could not read the file or its contents.")
            }
        }
        
        return nil
    }
}