swift-codable-KeyedEncodingContainer-2.swift

extension KeyedEncodingContainer {
    
    mutating func encode(_ value: UIImage,
                         forKey key: KeyedEncodingContainer.Key) throws {
        
        let imageData = value.jpegData(compressionQuality: 1)
        let prefix = "data:image/jpeg;base64,"        
        
        guard let base64String = imageData?.base64EncodedString(options: .lineLength64Characters) else {
            throw EncodingError.invalidValue(value, EncodingError.Context(codingPath: codingPath, debugDescription: "Can't encode image to base64 string."))
        }
        
        try encode(prefix + base64String, forKey: key)
    }
    
}

extension KeyedDecodingContainer {
    
    public func decode(_ type: UIImage.Type, forKey key: KeyedDecodingContainer.Key) throws -> UIImage {
        let base64String = try decode(String.self, forKey: key)
        
        // data:image/svg+xml;base64,PD.....
        let components = base64String.split(separator: ",")
    
        if components.count != 2 {
            throw DecodingError.typeMismatch(type, DecodingError.Context(codingPath: codingPath, debugDescription: "Unsupported format"))
        }
        
        let dataString = String(components[1])
        if let dataDecoded = Data(base64Encoded: dataString, options: .ignoreUnknownCharacters), let image = UIImage(data: dataDecoded) {
            return image
        } else {
            throw DecodingError.typeMismatch(type, DecodingError.Context(codingPath: codingPath, debugDescription: "Unsupported format"))
        }
    }
    
}