我正在学习swift，我创建了一个包含显示图像的单元格的表，以及按MIME TYPE（使用路径扩展名）分组的类。 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格式）是从互联网上拍摄的，我不确定他们是否有扩展名 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MIME类型？ PS：对不起我的英语不好，这不是我的母语
答案 0 :(得分：44)
如果有人想从该文件的实际网址获取MimeType，这段代码对我有用：
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"
}
答案 1 :(得分：4)
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
答案 2 :(得分：3)
假设您收到的数据为NSData，请按照以下帖子：https://stackoverflow.com/a/5042365/2798777
以斯威夫特为例：
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])")
}
答案 3 :(得分：2)
要从UTI获取扩展程序，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 的 com.apple.quicktime-movie
答案 4 :(得分：0)
如果您需要检查URL是否包含某些图像或音频文件或视频文件，请使用以下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)
}
}
答案 5 :(得分：0)
借助 @Dmih 给出的答案，我对其进行了修改 根据我的项目要求，需要MIME类型字符串 上传所选文件。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 ""
}
}