How can you read a files MIME-type in objective-c
It's a bit hacky, but it should work, don't know for sure because I'm just guessing at it
There are two options:
- If you just need the MIME type, use the timeoutInterval: NSURLRequest.
- If you want the data as well, you should use the commented out NSURLRequest.
Make sure to perform the request in a thread though, since it's synchronous.
NSString* filePath = [[NSBundle mainBundle] pathForResource:@"imagename" ofType:@"jpg"];
NSString* fullPath = [filePath stringByExpandingTildeInPath];
NSURL* fileUrl = [NSURL fileURLWithPath:fullPath];
//NSURLRequest* fileUrlRequest = [[NSURLRequest alloc] initWithURL:fileUrl];
NSURLRequest* fileUrlRequest = [[NSURLRequest alloc] initWithURL:fileUrl cachePolicy:NSURLCacheStorageNotAllowed timeoutInterval:.1];
NSError* error = nil;
NSURLResponse* response = nil;
NSData* fileData = [NSURLConnection sendSynchronousRequest:fileUrlRequest returningResponse:&response error:&error];
fileData; // Ignore this if you're using the timeoutInterval
// request, since the data will be truncated.
NSString* mimeType = [response MIMEType];
[fileUrlRequest release];
Add MobileCoreServices framework.
Objective C:
#import <MobileCoreServices/MobileCoreServices.h>
NSString *fileExtension = [myFileURL pathExtension];
NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)fileExtension, NULL);
NSString *contentType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)UTI, kUTTagClassMIMEType);
Swift:
import MobileCoreServices
func mimeType(fileExtension: String) -> String? {
guard !fileExtension.isEmpty else { return nil }
if let utiRef = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, fileExtension as CFString, nil) {
let uti = utiRef.takeUnretainedValue()
utiRef.release()
if let mimeTypeRef = UTTypeCopyPreferredTagWithClass(UTI, kUTTagClassMIMEType) {
let mimeType = MIMETypeRef.takeUnretainedValue()
mimeTypeRef.release()
return mimeType as String
}
}
return nil
}
The accepted answer is problematic for large files, as others have mentioned. My app deals with video files, and loading an entire video file into memory is a good way to make iOS run out of memory. A better way to do this can be found here:
https://stackoverflow.com/a/5998683/1864774
Code from above link:
+ (NSString*) mimeTypeForFileAtPath: (NSString *) path {
if (![[NSFileManager defaultManager] fileExistsAtPath:path]) {
return nil;
}
// Borrowed from https://stackoverflow.com/questions/5996797/determine-mime-type-of-nsdata-loaded-from-a-file
// itself, derived from https://stackoverflow.com/questions/2439020/wheres-the-iphone-mime-type-database
CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (CFStringRef)[path pathExtension], NULL);
CFStringRef mimeType = UTTypeCopyPreferredTagWithClass (UTI, kUTTagClassMIMEType);
CFRelease(UTI);
if (!mimeType) {
return @"application/octet-stream";
}
return [NSMakeCollectable((NSString *)mimeType) autorelease];
}