Magic

This library allows you to determine the MIME type or UTType for any data and is a Swift wrapper for libmagic(3) which is part of file(1) command. This implementation is based on Apple's adaptation of libmagic for macOS.

• Sources for libmagic: https://github.com/apple-opensource/file
• Home page for file: https://www.darwinsys.com/file/

Installation

Xcode

you can include Magic in your Xcode project via File | Swift Packages | Add Package Dependencies.... In the first step of the wizard use the URL https://github.com/macmoonshine/magic, press Next and following the remaining steps of the wizard.

Swift Package Manager

dependencies: [
    .package(url: "https://github.com/macmoonshine/magic.git"),
],
targets: [
    .target(
      name: "MyTarget",
      dependencies: [.product(name: "Magic", package: "Magic")]
    ),
]

Examples

You can use the class Magic to determine the media type of files or data as a string.

import Magic

let magic = Magic(definition: .default)
let data: Data! = "{}".data(using: .utf8)
let path = "..."

print(magic.file(data: data))
print(magic.file(path: path))

The definition: default directive tells libmagic to use the default location for the magic.mgc file. But you can also use your own file via:

let magic = Magic(definition: .path("/.../magic.mgc"))

Further possibilities can be found in Magic.Definition. Without a definition, the initialisation of Magic will fail.

Magic also offers an extension for Apple's Uniform Type Identifiers:

import Magic
import UniformTypeIdentifiers

let data: Data! = "{}".data(using: .utf8)
let dataType = UTType(data: data)
let fileTye = UTType(path: "...")

Furthermore, Magic provides the struct MediaType, which was implemented on the basis of RFC 2045 Section 5.1 and that allows easy access to the properties of media types. This allows, for example, a simple selection of views in SwiftUI depending on the data content.

import Magic
import SwiftUI

struct Preview: View {
    @State var data: Data
    
    var mediaType: MediaType? {
        return MediaType(data: data)
    }
    
    var body: some View {
        if let mediaType = mediaType {
            switch mediaType.mainType {
            case .audio:
                AudioPlayer(data: data)
            case .image:
                ImagePreview(data: data)
            case .text:
                TextPreview(data: data, encoding: mediaType.charset)
            default:
                Text("No preview available.")
            }
        }
        else {
            Text("Cannot determine media type.")        
        }
    }
}

The MediaType structure also makes it easy to create syntactically correct media type strings:

import Magic

let mediaType = MediaType(
    type: .application, subtype: "soap+xml", 
    parameters: .charset(.utf8), .init(name: "action", value: "urn:CreateCredential")
)
let headers = ["Content-Type": mediaType.description]

License

Copyright 2025 macoonshine

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.