ALAssetRepresentation *rep = [asset defaultRepresentation];
NSString* MIMEType = (__bridge_transfer NSString*)UTTypeCopyPreferredTagWithClass
((__bridge CFStringRef)[rep UTI], kUTTagClassMIMEType);
This will give you the MIME type. You need to add MobileCoreService framework and import <MobileCoreServices/MobileCoreServices.h>