Determine MIME type from NSData?

Question

How would you determine the mime type for an NSData object? I plan to have the user to upload a video/picture from their iPhone and have that file be wrapped in a NSData class.

I was wondering if I can tell the mime type from the NSData. There are only a few answers to this question and the most recent one is from 2010 (4 years ago!). Thanks!

NSData *data; // can be an image or video NSString *mimeType = [data getMimetype]; // how would I implement getMimeType 

Answer 1

Based on ml's answer from a similar post, I've added the mime types determination for NSData:

ObjC:

+ (NSString *)mimeTypeForData:(NSData *)data {     uint8_t c;     [data getBytes:&c length:1];      switch (c) {         case 0xFF:             return @"image/jpeg";             break;         case 0x89:             return @"image/png";             break;         case 0x47:             return @"image/gif";             break;         case 0x49:         case 0x4D:             return @"image/tiff";             break;         case 0x25:             return @"application/pdf";             break;         case 0xD0:             return @"application/vnd";             break;         case 0x46:             return @"text/plain";             break;         default:             return @"application/octet-stream";     }     return nil; } 

Swift:

static func mimeType(for data: Data) -> String {      var b: UInt8 = 0     data.copyBytes(to: &b, count: 1)      switch b {     case 0xFF:         return "image/jpeg"     case 0x89:         return "image/png"     case 0x47:         return "image/gif"     case 0x4D, 0x49:         return "image/tiff"     case 0x25:         return "application/pdf"     case 0xD0:         return "application/vnd"     case 0x46:         return "text/plain"     default:         return "application/octet-stream"     } } 

This handle main file types only, but you can complete it to fit your needs: all the files signature are available here, just use the same pattern as I did.

PS: all the corresponding mime types are available here