swift中文件的路径扩展名和MIME类型

Question

我正在快速学习，我制作了一个表格，其中包含显示图像的单元格和按 MIME TYPE 分组的类（使用路径扩展名）。 我有一个关于扩展的问题。 如果图像（例如，它可能是视频或 pdf）是从互联网上获取的，我不确定它们是否有扩展名 如何在不使用路径扩展名的情况下获取文件系统中文件的 MIMEtype ？ PS：对不起，我的英语不好，这不是我的母语

Answer 1

如果有人想从文件的实际 URL 中获取 MimeType，此代码对我有用：

import MobileCoreServices

func mimeTypeForPath(path: String) -> String {
    let url = NSURL(fileURLWithPath: path)
    let pathExtension = url.pathExtension

    if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension! as NSString, nil)?.takeRetainedValue() {
        if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
            return mimetype as String
        }
    }
    return "application/octet-stream"
}

Answer 2

如果您需要检查 URL 是否包含一些图像或音频文件或视频文件，这里是 Swift 5.1 代码：

import Foundation
import MobileCoreServices

extension URL {
    func mimeType() -> String {
        let pathExtension = self.pathExtension
        if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension as NSString, nil)?.takeRetainedValue() {
            if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
                return mimetype as String
            }
        }
        return "application/octet-stream"
    }
    var containsImage: Bool {
        let mimeType = self.mimeType()
        guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeImage)
    }
    var containsAudio: Bool {
        let mimeType = self.mimeType()
        guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeAudio)
    }
    var containsVideo: Bool {
        let mimeType = self.mimeType()
        guard  let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeMovie)
    }

}

Answer 3

使用以下代码

MimeType.swift

import Foundation

internal let DEFAULT_MIME_TYPE = "application/octet-stream"

internal let mimeTypes = [
    "html": "text/html",
    "htm": "text/html",
    "shtml": "text/html",
    "css": "text/css",
    "xml": "text/xml",
    "gif": "image/gif",
    "jpeg": "image/jpeg",
    "jpg": "image/jpeg",
    "js": "application/javascript",
    "atom": "application/atom+xml",
    "rss": "application/rss+xml",
    "mml": "text/mathml",
    "txt": "text/plain",
    "jad": "text/vnd.sun.j2me.app-descriptor",
    "wml": "text/vnd.wap.wml",
    "htc": "text/x-component",
    "png": "image/png",
    "tif": "image/tiff",
    "tiff": "image/tiff",
    "wbmp": "image/vnd.wap.wbmp",
    "ico": "image/x-icon",
    "jng": "image/x-jng",
    "bmp": "image/x-ms-bmp",
    "svg": "image/svg+xml",
    "svgz": "image/svg+xml",
    "webp": "image/webp",
    "woff": "application/font-woff",
    "jar": "application/java-archive",
    "war": "application/java-archive",
    "ear": "application/java-archive",
    "json": "application/json",
    "hqx": "application/mac-binhex40",
    "doc": "application/msword",
    "pdf": "application/pdf",
    "ps": "application/postscript",
    "eps": "application/postscript",
    "ai": "application/postscript",
    "rtf": "application/rtf",
    "m3u8": "application/vnd.apple.mpegurl",
    "xls": "application/vnd.ms-excel",
    "eot": "application/vnd.ms-fontobject",
    "ppt": "application/vnd.ms-powerpoint",
    "wmlc": "application/vnd.wap.wmlc",
    "kml": "application/vnd.google-earth.kml+xml",
    "kmz": "application/vnd.google-earth.kmz",
    "7z": "application/x-7z-compressed",
    "cco": "application/x-cocoa",
    "jardiff": "application/x-java-archive-diff",
    "jnlp": "application/x-java-jnlp-file",
    "run": "application/x-makeself",
    "pl": "application/x-perl",
    "pm": "application/x-perl",
    "prc": "application/x-pilot",
    "pdb": "application/x-pilot",
    "rar": "application/x-rar-compressed",
    "rpm": "application/x-redhat-package-manager",
    "sea": "application/x-sea",
    "swf": "application/x-shockwave-flash",
    "sit": "application/x-stuffit",
    "tcl": "application/x-tcl",
    "tk": "application/x-tcl",
    "der": "application/x-x509-ca-cert",
    "pem": "application/x-x509-ca-cert",
    "crt": "application/x-x509-ca-cert",
    "xpi": "application/x-xpinstall",
    "xhtml": "application/xhtml+xml",
    "xspf": "application/xspf+xml",
    "zip": "application/zip",
    "epub": "application/epub+zip",
    "docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    "xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
    "mid": "audio/midi",
    "midi": "audio/midi",
    "kar": "audio/midi",
    "mp3": "audio/mpeg",
    "ogg": "audio/ogg",
    "m4a": "audio/x-m4a",
    "ra": "audio/x-realaudio",
    "3gpp": "video/3gpp",
    "3gp": "video/3gpp",
    "ts": "video/mp2t",
    "mp4": "video/mp4",
    "mpeg": "video/mpeg",
    "mpg": "video/mpeg",
    "mov": "video/quicktime",
    "webm": "video/webm",
    "flv": "video/x-flv",
    "m4v": "video/x-m4v",
    "mng": "video/x-mng",
    "asx": "video/x-ms-asf",
    "asf": "video/x-ms-asf",
    "wmv": "video/x-ms-wmv",
    "avi": "video/x-msvideo"
]

internal func MimeType(ext: String?) -> String {
    return mimeTypes[ext?.lowercased() ?? "" ] ?? DEFAULT_MIME_TYPE
}

extension NSURL {
    public func mimeType() -> String {
        return MimeType(ext: self.pathExtension)
    }
}

extension URL {
    public func mimeType() -> String {
        return MimeType(ext: self.pathExtension)
    }
}

extension NSString {
    public func mimeType() -> String {
        return MimeType(ext: self.pathExtension)
    }
}

extension String {
    public func mimeType() -> String {
        return (self as NSString).mimeType()
    }
}

如何使用

let string = "https://homepages.cae.wisc.edu/~ece533/images/boat.png"

let mimeType = string.mimeType()

适用于 NSURL、URL、NSString、String

参考：https://gist.github.com/ngs/918b07f448977789cf69

Answer 4

要从 UTI 获取扩展，这里是 Swift 4.1 代码：

import AVFoundation

extension AVFileType {
    /// Fetch and extension for a file from UTI string
    var fileExtension: String {
        if let ext = UTTypeCopyPreferredTagWithClass(self as CFString, kUTTagClassFilenameExtension)?.takeRetainedValue() {
            return ext as String
        }
        return "None"
    }
}

mov 为com.apple.quicktime-movie

Answer 5

假设您以 NSData 的形式接收数据，请关注此帖子：https://stackoverflow.com/a/5042365/2798777

以 Swift 为例：

var c = [UInt32](count: 1, repeatedValue: 0)
(data as! NSData).getBytes(&c, length: 1)
switch (c[0]) {
case 0xFF, 0x89, 0x00:
    println("image")
case 0x47:
    println("gif")
default: 
    println("unknown: \(c[0])")
}

Answer 6

iOS15兼容版@Dmih's solution如下图：

import UniformTypeIdentifiers

extension URL {
    func mimeType() -> String {
        let pathExtension = self.pathExtension
        if let type = UTType(filenameExtension: pathExtension) {
            if let mimetype = type.preferredMIMEType {
                return mimetype as String
            }
        }
        return "application/octet-stream"
    }
    
    var containsImage: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .image)
        }
        return false
    }
    
    var containsAudio: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .audio)
        }
        return false
    }
    
    var containsMovie: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .movie)   // ex. .mp4-movies
        }
        return false
    }
    
    var containsVideo: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .video)
        }
        return false
    }
}

Answer 7

在 @Dmih 给出的答案的帮助下，我修改了它 根据我需要 mime 类型字符串的项目要求 上传选定的文件。这可能对其他人有帮助。

  import Foundation
  import MobileCoreServices



  extension URL {
                func mimeType() -> String {
                    let pathExtension = self.pathExtension
                    if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension as NSString, nil)?.takeRetainedValue() {
                        if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
                            return mimetype as String
                        }
                    }
                    return "application/octet-stream"
                }
                var containsImage: Bool {
                    let mimeType = self.mimeType()
                    guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
                        return false
                    }
                    return UTTypeConformsTo(uti, kUTTypeImage)
                }
                var containsAudio: Bool {
                    let mimeType = self.mimeType()
                    guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
                        return false
                    }
                    return UTTypeConformsTo(uti, kUTTypeAudio)
                }
                var containsVideo: Bool {
                    let mimeType = self.mimeType()
                    guard  let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
                        return false
                    }
                    return UTTypeConformsTo(uti, kUTTypeMovie)
                }

            //Get current mime type of url w.r.t its url
                var currentMimeType: String {

                    if self.containsImage{
                        return "image/png"
                    }else if self.containsAudio{
                        return "audio/mp3"
                    }else if self.containsVideo{
                        return "video/mp4"
                    }

                    return ""
                }
            }