alternativement, si vous travaillez dans .Net v4.5 ou plus, essayez d'utiliser le système .Web.MimeMapping.GetMimeMapping ( votre nomfilen) pour obtenir des types MIME-beaucoup mieux que des chaînes de codage dur

à charger .fichier docx

    if let htmlFile = Bundle.main.path(forResource: "fileName", ofType: "docx") {
        let url = URL(fileURLWithPath: htmlFile)
        do{
            let data = try Data(contentsOf: url)
            self.webView.load(data, mimeType: "application/vnd.openxmlformats-officedocument.wordprocessingml.document", textEncodingName: "UTF-8", baseURL: url)
        }catch{
            print("errrr")
        }
    }

voici un MIME (presque) complet de toutes les extensions de fichier dans un format JSON. Il suffit de ne exemple: MIME["ppt"], MIME["docx"], etc

{"x3d": "application/vnd.hzn-3d-crossword", "3gp": "video/3gpp", "3g2": "video/3gpp2", "mseq": "application/vnd.mseq", "pwn": "application/vnd.3m.post-it-notes", "plb": "application/vnd.3gpp.pic-bw-large", "psb": "application/vnd.3gpp.pic-bw-small", "pvb": "application/vnd.3gpp.pic-bw-var", "tcap": "application/vnd.3gpp2.tcap", "7z": "application/x-7z-compressed", "abw": "application/x-abiword", "ace": "application/x-ace-compressed", "acc": "application/vnd.americandynamics.acc", "acu": "application/vnd.acucobol", "atc": "application/vnd.acucorp", "adp": "audio/adpcm", "aab": "application/x-authorware-bin", "aam": "application/x-authorware-map", "aas": "application/x-authorware-seg", "air": "application/vnd.adobe.air-application-installer-package+zip", "swf": "application/x-shockwave-flash", "fxp": "application/vnd.adobe.fxp", "pdf": "application/pdf", "ppd": "application/vnd.cups-ppd", "dir": "application/x-director", "xdp": "application/vnd.adobe.xdp+xml", "xfdf": "application/vnd.adobe.xfdf", "aac": "audio/x-aac", "ahead": "application/vnd.ahead.space", "azf": "application/vnd.airzip.filesecure.azf", "azs": "application/vnd.airzip.filesecure.azs", "azw": "application/vnd.amazon.ebook", "ami": "application/vnd.amiga.ami", "N/A": "application/andrew-inset", "apk": "application/vnd.android.package-archive", "cii": "application/vnd.anser-web-certificate-issue-initiation", "fti": "application/vnd.anser-web-funds-transfer-initiation", "atx": "application/vnd.antix.game-component", "dmg": "application/x-apple-diskimage", "mpkg": "application/vnd.apple.installer+xml", "aw": "application/applixware", "les": "application/vnd.hhe.lesson-player", "swi": "application/vnd.aristanetworks.swi", "s": "text/x-asm", "atomcat": "application/atomcat+xml", "atomsvc": "application/atomsvc+xml", "atom, .xml": "application/atom+xml", "ac": "application/pkix-attr-cert", "aif": "audio/x-aiff", "avi": "video/x-msvideo", "aep": "application/vnd.audiograph", "dxf": "image/vnd.dxf", "dwf": "model/vnd.dwf", "par": "text/plain-bas", "bcpio": "application/x-bcpio", "bin": "application/octet-stream", "bmp": "image/bmp", "torrent": "application/x-bittorrent", "cod": "application/vnd.rim.cod", "mpm": "application/vnd.blueice.multipass", "bmi": "application/vnd.bmi", "sh": "application/x-sh", "btif": "image/prs.btif", "rep": "application/vnd.businessobjects", "bz": "application/x-bzip", "bz2": "application/x-bzip2", "csh": "application/x-csh", "c": "text/x-c", "cdxml": "application/vnd.chemdraw+xml", "css": "text/css", "cdx": "chemical/x-cdx", "cml": "chemical/x-cml", "csml": "chemical/x-csml", "cdbcmsg": "application/vnd.contact.cmsg", "cla": "application/vnd.claymore", "c4g": "application/vnd.clonk.c4group", "sub": "image/vnd.dvb.subtitle", "cdmia": "application/cdmi-capability", "cdmic": "application/cdmi-container", "cdmid": "application/cdmi-domain", "cdmio": "application/cdmi-object", "cdmiq": "application/cdmi-queue", "c11amc": "application/vnd.cluetrust.cartomobile-config", "c11amz": "application/vnd.cluetrust.cartomobile-config-pkg", "ras": "image/x-cmu-raster", "dae": "model/vnd.collada+xml", "csv": "text/csv", "cpt": "application/mac-compactpro", "wmlc": "application/vnd.wap.wmlc", "cgm": "image/cgm", "ice": "x-conference/x-cooltalk", "cmx": "image/x-cmx", "xar": "application/vnd.xara", "cmc": "application/vnd.cosmocaller", "cpio": "application/x-cpio", "clkx": "application/vnd.crick.clicker", "clkk": "application/vnd.crick.clicker.keyboard", "clkp": "application/vnd.crick.clicker.palette", "clkt": "application/vnd.crick.clicker.template", "clkw": "application/vnd.crick.clicker.wordbank", "wbs": "application/vnd.criticaltools.wbs+xml", "cryptonote": "application/vnd.rig.cryptonote", "cif": "chemical/x-cif", "cmdf": "chemical/x-cmdf", "cu": "application/cu-seeme", "cww": "application/prs.cww", "curl": "text/vnd.curl", "dcurl": "text/vnd.curl.dcurl", "mcurl": "text/vnd.curl.mcurl", "scurl": "text/vnd.curl.scurl", "car": "application/vnd.curl.car", "pcurl": "application/vnd.curl.pcurl", "cmp": "application/vnd.yellowriver-custom-menu", "dssc": "application/dssc+der", "xdssc": "application/dssc+xml", "deb": "application/x-debian-package", "uva": "audio/vnd.dece.audio", "uvi": "image/vnd.dece.graphic", "uvh": "video/vnd.dece.hd", "uvm": "video/vnd.dece.mobile", "uvu": "video/vnd.uvvu.mp4", "uvp": "video/vnd.dece.pd", "uvs": "video/vnd.dece.sd", "uvv": "video/vnd.dece.video", "dvi": "application/x-dvi", "seed": "application/vnd.fdsn.seed", "dtb": "application/x-dtbook+xml", "res": "application/x-dtbresource+xml", "ait": "application/vnd.dvb.ait", "svc": "application/vnd.dvb.service", "eol": "audio/vnd.digital-winds", "djvu": "image/vnd.djvu", "dtd": "application/xml-dtd", "mlp": "application/vnd.dolby.mlp", "wad": "application/x-doom", "dpg": "application/vnd.dpgraph", "dra": "audio/vnd.dra", "dfac": "application/vnd.dreamfactory", "dts": "audio/vnd.dts", "dtshd": "audio/vnd.dts.hd", "dwg": "image/vnd.dwg", "geo": "application/vnd.dynageo", "es": "application/ecmascript", "mag": "application/vnd.ecowin.chart", "mmr": "image/vnd.fujixerox.edmics-mmr", "rlc": "image/vnd.fujixerox.edmics-rlc", "exi": "application/exi", "mgz": "application/vnd.proteus.magazine", "epub": "application/epub+zip", "eml": "message/rfc822", "nml": "application/vnd.enliven", "xpr": "application/vnd.is-xpr", "xif": "image/vnd.xiff", "xfdl": "application/vnd.xfdl", "emma": "application/emma+xml", "ez2": "application/vnd.ezpix-album", "ez3": "application/vnd.ezpix-package", "fst": "image/vnd.fst", "fvt": "video/vnd.fvt", "fbs": "image/vnd.fastbidsheet", "fe_launch": "application/vnd.denovo.fcselayout-link", "f4v": "video/x-f4v", "flv": "video/x-flv", "fpx": "image/vnd.fpx", "npx": "image/vnd.net-fpx", "flx": "text/vnd.fmi.flexstor", "fli": "video/x-fli", "ftc": "application/vnd.fluxtime.clip", "fdf": "application/vnd.fdf", "f": "text/x-fortran", "mif": "application/vnd.mif", "fm": "application/vnd.framemaker", "fh": "image/x-freehand", "fsc": "application/vnd.fsc.weblaunch", "fnc": "application/vnd.frogans.fnc", "ltf": "application/vnd.frogans.ltf", "ddd": "application/vnd.fujixerox.ddd", "xdw": "application/vnd.fujixerox.docuworks", "xbd": "application/vnd.fujixerox.docuworks.binder", "oas": "application/vnd.fujitsu.oasys", "oa2": "application/vnd.fujitsu.oasys2", "oa3": "application/vnd.fujitsu.oasys3", "fg5": "application/vnd.fujitsu.oasysgp", "bh2": "application/vnd.fujitsu.oasysprs", "spl": "application/x-futuresplash", "fzs": "application/vnd.fuzzysheet", "g3": "image/g3fax", "gmx": "application/vnd.gmx", "gtw": "model/vnd.gtw", "txd": "application/vnd.genomatix.tuxedo", "ggb": "application/vnd.geogebra.file", "ggt": "application/vnd.geogebra.tool", "gdl": "model/vnd.gdl", "gex": "application/vnd.geometry-explorer", "gxt": "application/vnd.geonext", "g2w": "application/vnd.geoplan", "g3w": "application/vnd.geospace", "gsf": "application/x-font-ghostscript", "bdf": "application/x-font-bdf", "gtar": "application/x-gtar", "texinfo": "application/x-texinfo", "gnumeric": "application/x-gnumeric", "kml": "application/vnd.google-earth.kml+xml", "kmz": "application/vnd.google-earth.kmz", "gqf": "application/vnd.grafeq", "gif": "image/gif", "gv": "text/vnd.graphviz", "gac": "application/vnd.groove-account", "ghf": "application/vnd.groove-help", "gim": "application/vnd.groove-identity-message", "grv": "application/vnd.groove-injector", "gtm": "application/vnd.groove-tool-message", "tpl": "application/vnd.groove-tool-template", "vcg": "application/vnd.groove-vcard", "h261": "video/h261", "h263": "video/h263", "h264": "video/h264", "hpid": "application/vnd.hp-hpid", "hps": "application/vnd.hp-hps", "hdf": "application/x-hdf", "rip": "audio/vnd.rip", "hbci": "application/vnd.hbci", "jlt": "application/vnd.hp-jlyt", "pcl": "application/vnd.hp-pcl", "hpgl": "application/vnd.hp-hpgl", "hvs": "application/vnd.yamaha.hv-script", "hvd": "application/vnd.yamaha.hv-dic", "hvp": "application/vnd.yamaha.hv-voice", "sfd-hdstx": "application/vnd.hydrostatix.sof-data", "stk": "application/hyperstudio", "hal": "application/vnd.hal+xml", "html": "text/html", "irm": "application/vnd.ibm.rights-management", "sc": "application/vnd.ibm.secure-container", "ics": "text/calendar", "icc": "application/vnd.iccprofile", "ico": "image/x-icon", "igl": "application/vnd.igloader", "ief": "image/ief", "ivp": "application/vnd.immervision-ivp", "ivu": "application/vnd.immervision-ivu", "rif": "application/reginfo+xml", "3dml": "text/vnd.in3d.3dml", "spot": "text/vnd.in3d.spot", "igs": "model/iges", "i2g": "application/vnd.intergeo", "cdy": "application/vnd.cinderella", "xpw": "application/vnd.intercon.formnet", "fcs": "application/vnd.isac.fcs", "ipfix": "application/ipfix", "cer": "application/pkix-cert", "pki": "application/pkixcmp", "crl": "application/pkix-crl", "pkipath": "application/pkix-pkipath", "igm": "application/vnd.insors.igm", "rcprofile": "application/vnd.ipunplugged.rcprofile", "irp": "application/vnd.irepository.package+xml", "jad": "text/vnd.sun.j2me.app-descriptor", "jar": "application/java-archive", "class": "application/java-vm", "jnlp": "application/x-java-jnlp-file", "ser": "application/java-serialized-object", "java": "text/x-java-source,java", "js": "application/javascript", "json": "application/json", "joda": "application/vnd.joost.joda-archive", "jpm": "video/jpm", "jpeg, .jpg": "image/x-citrix-jpeg", "pjpeg": "image/pjpeg", "jpgv": "video/jpeg", "ktz": "application/vnd.kahootz", "mmd": "application/vnd.chipnuts.karaoke-mmd", "karbon": "application/vnd.kde.karbon", "chrt": "application/vnd.kde.kchart", "kfo": "application/vnd.kde.kformula", "flw": "application/vnd.kde.kivio", "kon": "application/vnd.kde.kontour", "kpr": "application/vnd.kde.kpresenter", "ksp": "application/vnd.kde.kspread", "kwd": "application/vnd.kde.kword", "htke": "application/vnd.kenameaapp", "kia": "application/vnd.kidspiration", "kne": "application/vnd.kinar", "sse": "application/vnd.kodak-descriptor", "lasxml": "application/vnd.las.las+xml", "latex": "application/x-latex", "lbd": "application/vnd.llamagraphics.life-balance.desktop", "lbe": "application/vnd.llamagraphics.life-balance.exchange+xml", "jam": "application/vnd.jam", "123": "application/vnd.lotus-1-2-3", "apr": "application/vnd.lotus-approach", "pre": "application/vnd.lotus-freelance", "nsf": "application/vnd.lotus-notes", "org": "application/vnd.lotus-organizer", "scm": "application/vnd.lotus-screencam", "lwp": "application/vnd.lotus-wordpro", "lvp": "audio/vnd.lucent.voice", "m3u": "audio/x-mpegurl", "m4v": "video/x-m4v", "hqx": "application/mac-binhex40", "portpkg": "application/vnd.macports.portpkg", "mgp": "application/vnd.osgeo.mapguide.package", "mrc": "application/marc", "mrcx": "application/marcxml+xml", "mxf": "application/mxf", "nbp": "application/vnd.wolfram.player", "ma": "application/mathematica", "mathml": "application/mathml+xml", "mbox": "application/mbox", "mc1": "application/vnd.medcalcdata", "mscml": "application/mediaservercontrol+xml", "cdkey": "application/vnd.mediastation.cdkey", "mwf": "application/vnd.mfer", "mfm": "application/vnd.mfmp", "msh": "model/mesh", "mads": "application/mads+xml", "mets": "application/mets+xml", "mods": "application/mods+xml", "meta4": "application/metalink4+xml", "mcd": "application/vnd.mcd", "flo": "application/vnd.micrografx.flo", "igx": "application/vnd.micrografx.igx", "es3": "application/vnd.eszigno3+xml", "mdb": "application/x-msaccess", "asf": "video/x-ms-asf", "exe": "application/x-msdownload", "cil": "application/vnd.ms-artgalry", "cab": "application/vnd.ms-cab-compressed", "ims": "application/vnd.ms-ims", "application": "application/x-ms-application", "clp": "application/x-msclip", "mdi": "image/vnd.ms-modi", "eot": "application/vnd.ms-fontobject", "xls": "application/vnd.ms-excel", "xlam": "application/vnd.ms-excel.addin.macroenabled.12", "xlsb": "application/vnd.ms-excel.sheet.binary.macroenabled.12", "xltm": "application/vnd.ms-excel.template.macroenabled.12", "xlsm": "application/vnd.ms-excel.sheet.macroenabled.12", "chm": "application/vnd.ms-htmlhelp", "crd": "application/x-mscardfile", "lrm": "application/vnd.ms-lrm", "mvb": "application/x-msmediaview", "mny": "application/x-msmoney", "pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation", "sldx": "application/vnd.openxmlformats-officedocument.presentationml.slide", "ppsx": "application/vnd.openxmlformats-officedocument.presentationml.slideshow", "potx": "application/vnd.openxmlformats-officedocument.presentationml.template", "xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "xltx": "application/vnd.openxmlformats-officedocument.spreadsheetml.template", "docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "dotx": "application/vnd.openxmlformats-officedocument.wordprocessingml.template", "obd": "application/x-msbinder", "thmx": "application/vnd.ms-officetheme", "onetoc": "application/onenote", "pya": "audio/vnd.ms-playready.media.pya", "pyv": "video/vnd.ms-playready.media.pyv", "ppt": "application/vnd.ms-powerpoint", "ppam": "application/vnd.ms-powerpoint.addin.macroenabled.12", "sldm": "application/vnd.ms-powerpoint.slide.macroenabled.12", "pptm": "application/vnd.ms-powerpoint.presentation.macroenabled.12", "ppsm": "application/vnd.ms-powerpoint.slideshow.macroenabled.12", "potm": "application/vnd.ms-powerpoint.template.macroenabled.12", "mpp": "application/vnd.ms-project", "pub": "application/x-mspublisher", "scd": "application/x-msschedule", "xap": "application/x-silverlight-app", "stl": "application/vnd.ms-pki.stl", "cat": "application/vnd.ms-pki.seccat", "vsd": "application/vnd.visio", "vsdx": "application/vnd.visio2013", "wm": "video/x-ms-wm", "wma": "audio/x-ms-wma", "wax": "audio/x-ms-wax", "wmx": "video/x-ms-wmx", "wmd": "application/x-ms-wmd", "wpl": "application/vnd.ms-wpl", "wmz": "application/x-ms-wmz", "wmv": "video/x-ms-wmv", "wvx": "video/x-ms-wvx", "wmf": "application/x-msmetafile", "trm": "application/x-msterminal", "doc": "application/msword", "docm": "application/vnd.ms-word.document.macroenabled.12", "dotm": "application/vnd.ms-word.template.macroenabled.12", "wri": "application/x-mswrite", "wps": "application/vnd.ms-works", "xbap": "application/x-ms-xbap", "xps": "application/vnd.ms-xpsdocument", "mid": "audio/midi", "mpy": "application/vnd.ibm.minipay", "afp": "application/vnd.ibm.modcap", "rms": "application/vnd.jcp.javame.midlet-rms", "tmo": "application/vnd.tmobile-livetv", "prc": "application/x-mobipocket-ebook", "mbk": "application/vnd.mobius.mbk", "dis": "application/vnd.mobius.dis", "plc": "application/vnd.mobius.plc", "mqy": "application/vnd.mobius.mqy", "msl": "application/vnd.mobius.msl", "txf": "application/vnd.mobius.txf", "daf": "application/vnd.mobius.daf", "fly": "text/vnd.fly", "mpc": "application/vnd.mophun.certificate", "mpn": "application/vnd.mophun.application", "mj2": "video/mj2", "mpga": "audio/mpeg", "mxu": "video/vnd.mpegurl", "mpeg": "video/mpeg", "m21": "application/mp21", "mp4a": "audio/mp4", "mp4": "application/mp4", "m3u8": "application/vnd.apple.mpegurl", "mus": "application/vnd.musician", "msty": "application/vnd.muvee.style", "mxml": "application/xv+xml", "ngdat": "application/vnd.nokia.n-gage.data", "n-gage": "application/vnd.nokia.n-gage.symbian.install", "ncx": "application/x-dtbncx+xml", "nc": "application/x-netcdf", "nlu": "application/vnd.neurolanguage.nlu", "dna": "application/vnd.dna", "nnd": "application/vnd.noblenet-directory", "nns": "application/vnd.noblenet-sealer", "nnw": "application/vnd.noblenet-web", "rpst": "application/vnd.nokia.radio-preset", "rpss": "application/vnd.nokia.radio-presets", "n3": "text/n3", "edm": "application/vnd.novadigm.edm", "edx": "application/vnd.novadigm.edx", "ext": "application/vnd.novadigm.ext", "gph": "application/vnd.flographit", "ecelp4800": "audio/vnd.nuera.ecelp4800", "ecelp7470": "audio/vnd.nuera.ecelp7470", "ecelp9600": "audio/vnd.nuera.ecelp9600", "oda": "application/oda", "ogx": "application/ogg", "oga": "audio/ogg", "ogv": "video/ogg", "dd2": "application/vnd.oma.dd2+xml", "oth": "application/vnd.oasis.opendocument.text-web", "opf": "application/oebps-package+xml", "qbo": "application/vnd.intu.qbo", "oxt": "application/vnd.openofficeorg.extension", "osf": "application/vnd.yamaha.openscoreformat", "weba": "audio/webm", "webm": "video/webm", "odc": "application/vnd.oasis.opendocument.chart", "otc": "application/vnd.oasis.opendocument.chart-template", "odb": "application/vnd.oasis.opendocument.database", "odf": "application/vnd.oasis.opendocument.formula", "odft": "application/vnd.oasis.opendocument.formula-template", "odg": "application/vnd.oasis.opendocument.graphics", "otg": "application/vnd.oasis.opendocument.graphics-template", "odi": "application/vnd.oasis.opendocument.image", "oti": "application/vnd.oasis.opendocument.image-template", "odp": "application/vnd.oasis.opendocument.presentation", "otp": "application/vnd.oasis.opendocument.presentation-template", "ods": "application/vnd.oasis.opendocument.spreadsheet", "ots": "application/vnd.oasis.opendocument.spreadsheet-template", "odt": "application/vnd.oasis.opendocument.text", "odm": "application/vnd.oasis.opendocument.text-master", "ott": "application/vnd.oasis.opendocument.text-template", "ktx": "image/ktx", "sxc": "application/vnd.sun.xml.calc", "stc": "application/vnd.sun.xml.calc.template", "sxd": "application/vnd.sun.xml.draw", "std": "application/vnd.sun.xml.draw.template", "sxi": "application/vnd.sun.xml.impress", "sti": "application/vnd.sun.xml.impress.template", "sxm": "application/vnd.sun.xml.math", "sxw": "application/vnd.sun.xml.writer", "sxg": "application/vnd.sun.xml.writer.global", "stw": "application/vnd.sun.xml.writer.template", "otf": "application/x-font-otf", "osfpvg": "application/vnd.yamaha.openscoreformat.osfpvg+xml", "dp": "application/vnd.osgi.dp", "pdb": "application/vnd.palm", "p": "text/x-pascal", "paw": "application/vnd.pawaafile", "pclxl": "application/vnd.hp-pclxl", "efif": "application/vnd.picsel", "pcx": "image/x-pcx", "psd": "image/vnd.adobe.photoshop", "prf": "application/pics-rules", "pic": "image/x-pict", "chat": "application/x-chat", "p10": "application/pkcs10", "p12": "application/x-pkcs12", "p7m": "application/pkcs7-mime", "p7s": "application/pkcs7-signature", "p7r": "application/x-pkcs7-certreqresp", "p7b": "application/x-pkcs7-certificates", "p8": "application/pkcs8", "plf": "application/vnd.pocketlearn", "pnm": "image/x-portable-anymap", "pbm": "image/x-portable-bitmap", "pcf": "application/x-font-pcf", "pfr": "application/font-tdpfr", "pgn": "application/x-chess-pgn", "pgm": "image/x-portable-graymap", "png": "image/x-png", "ppm": "image/x-portable-pixmap", "pskcxml": "application/pskc+xml", "pml": "application/vnd.ctc-posml", "ai": "application/postscript", "pfa": "application/x-font-type1", "pbd": "application/vnd.powerbuilder6", "pgp": "application/pgp-signature", "box": "application/vnd.previewsystems.box", "ptid": "application/vnd.pvi.ptid1", "pls": "application/pls+xml", "str": "application/vnd.pg.format", "ei6": "application/vnd.pg.osasli", "dsc": "text/prs.lines.tag", "psf": "application/x-font-linux-psf", "qps": "application/vnd.publishare-delta-tree", "wg": "application/vnd.pmi.widget", "qxd": "application/vnd.quark.quarkxpress", "esf": "application/vnd.epson.esf", "msf": "application/vnd.epson.msf", "ssf": "application/vnd.epson.ssf", "qam": "application/vnd.epson.quickanime", "qfx": "application/vnd.intu.qfx", "qt": "video/quicktime", "rar": "application/x-rar-compressed", "ram": "audio/x-pn-realaudio", "rmp": "audio/x-pn-realaudio-plugin", "rsd": "application/rsd+xml", "rm": "application/vnd.rn-realmedia", "bed": "application/vnd.realvnc.bed", "mxl": "application/vnd.recordare.musicxml", "musicxml": "application/vnd.recordare.musicxml+xml", "rnc": "application/relax-ng-compact-syntax", "rdz": "application/vnd.data-vision.rdz", "rdf": "application/rdf+xml", "rp9": "application/vnd.cloanto.rp9", "jisp": "application/vnd.jisp", "rtf": "application/rtf", "rtx": "text/richtext", "link66": "application/vnd.route66.link66+xml", "rss, .xml": "application/rss+xml", "shf": "application/shf+xml", "st": "application/vnd.sailingtracker.track", "svg": "image/svg+xml", "sus": "application/vnd.sus-calendar", "sru": "application/sru+xml", "setpay": "application/set-payment-initiation", "setreg": "application/set-registration-initiation", "sema": "application/vnd.sema", "semd": "application/vnd.semd", "semf": "application/vnd.semf", "see": "application/vnd.seemail", "snf": "application/x-font-snf", "spq": "application/scvp-vp-request", "spp": "application/scvp-vp-response", "scq": "application/scvp-cv-request", "scs": "application/scvp-cv-response", "sdp": "application/sdp", "etx": "text/x-setext", "movie": "video/x-sgi-movie", "ifm": "application/vnd.shana.informed.formdata", "itp": "application/vnd.shana.informed.formtemplate", "iif": "application/vnd.shana.informed.interchange", "ipk": "application/vnd.shana.informed.package", "tfi": "application/thraud+xml", "shar": "application/x-shar", "rgb": "image/x-rgb", "slt": "application/vnd.epson.salt", "aso": "application/vnd.accpac.simply.aso", "imp": "application/vnd.accpac.simply.imp", "twd": "application/vnd.simtech-mindmapper", "csp": "application/vnd.commonspace", "saf": "application/vnd.yamaha.smaf-audio", "mmf": "application/vnd.smaf", "spf": "application/vnd.yamaha.smaf-phrase", "teacher": "application/vnd.smart.teacher", "svd": "application/vnd.svd", "rq": "application/sparql-query", "srx": "application/sparql-results+xml", "gram": "application/srgs", "grxml": "application/srgs+xml", "ssml": "application/ssml+xml", "skp": "application/vnd.koan", "sgml": "text/sgml", "sdc": "application/vnd.stardivision.calc", "sda": "application/vnd.stardivision.draw", "sdd": "application/vnd.stardivision.impress", "smf": "application/vnd.stardivision.math", "sdw": "application/vnd.stardivision.writer", "sgl": "application/vnd.stardivision.writer-global", "sm": "application/vnd.stepmania.stepchart", "sit": "application/x-stuffit", "sitx": "application/x-stuffitx", "sdkm": "application/vnd.solent.sdkm+xml", "xo": "application/vnd.olpc-sugar", "au": "audio/basic", "wqd": "application/vnd.wqd", "sis": "application/vnd.symbian.install", "smi": "application/smil+xml", "xsm": "application/vnd.syncml+xml", "bdm": "application/vnd.syncml.dm+wbxml", "xdm": "application/vnd.syncml.dm+xml", "sv4cpio": "application/x-sv4cpio", "sv4crc": "application/x-sv4crc", "sbml": "application/sbml+xml", "tsv": "text/tab-separated-values", "tiff": "image/tiff", "tao": "application/vnd.tao.intent-module-archive", "tar": "application/x-tar", "tcl": "application/x-tcl", "tex": "application/x-tex", "tfm": "application/x-tex-tfm", "tei": "application/tei+xml", "txt": "text/plain", "dxp": "application/vnd.spotfire.dxp", "sfs": "application/vnd.spotfire.sfs", "tsd": "application/timestamped-data", "tpt": "application/vnd.trid.tpt", "mxs": "application/vnd.triscape.mxs", "t": "text/troff", "tra": "application/vnd.trueapp", "ttf": "application/x-font-ttf", "ttl": "text/turtle", "umj": "application/vnd.umajin", "uoml": "application/vnd.uoml+xml", "unityweb": "application/vnd.unity", "ufd": "application/vnd.ufdl", "uri": "text/uri-list", "utz": "application/vnd.uiq.theme", "ustar": "application/x-ustar", "uu": "text/x-uuencode", "vcs": "text/x-vcalendar", "vcf": "text/x-vcard", "vcd": "application/x-cdlink", "vsf": "application/vnd.vsf", "wrl": "model/vrml", "vcx": "application/vnd.vcx", "mts": "model/vnd.mts", "vtu": "model/vnd.vtu", "vis": "application/vnd.visionary", "viv": "video/vnd.vivo", "ccxml": "application/ccxml+xml,", "vxml": "application/voicexml+xml", "src": "application/x-wais-source", "wbxml": "application/vnd.wap.wbxml", "wbmp": "image/vnd.wap.wbmp", "wav": "audio/x-wav", "davmount": "application/davmount+xml", "woff": "application/x-font-woff", "wspolicy": "application/wspolicy+xml", "webp": "image/webp", "wtb": "application/vnd.webturbo", "wgt": "application/widget", "hlp": "application/winhlp", "wml": "text/vnd.wap.wml", "wmls": "text/vnd.wap.wmlscript", "wmlsc": "application/vnd.wap.wmlscriptc", "wpd": "application/vnd.wordperfect", "stf": "application/vnd.wt.stf", "wsdl": "application/wsdl+xml", "xbm": "image/x-xbitmap", "xpm": "image/x-xpixmap", "xwd": "image/x-xwindowdump", "der": "application/x-x509-ca-cert", "fig": "application/x-xfig", "xhtml": "application/xhtml+xml", "xml": "application/xml", "xdf": "application/xcap-diff+xml", "xenc": "application/xenc+xml", "xer": "application/patch-ops-error+xml", "rl": "application/resource-lists+xml", "rs": "application/rls-services+xml", "rld": "application/resource-lists-diff+xml", "xslt": "application/xslt+xml", "xop": "application/xop+xml", "xpi": "application/x-xpinstall", "xspf": "application/xspf+xml", "xul": "application/vnd.mozilla.xul+xml", "xyz": "chemical/x-xyz", "yaml": "text/yaml", "yang": "application/yang", "yin": "application/yin+xml", "zir": "application/vnd.zul", "zip": "application/zip", "zmm": "application/vnd.handheld-entertainment+xml", "zaz": "application/vnd.zzazz.deck+xml"}

Swift4

 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"
    }