Print the preferred UTI Document Type for a file extension, then print all possible matching UTI's and their definitions to debug problems.

DebugFileAssociations.m

@import CoreServices;

// All Bundle Ids
NSString *pathExtension = @"db";
NSLog(@"pathExtension: %@", pathExtension);
	
CFStringRef preferedUTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)pathExtension, NULL);
NSLog(@"%@ - Preferred UTI: %@", pathExtension, preferedUTI);
CFDictionaryRef defintion = UTTypeCopyDeclaration(preferedUTI);
NSLog(@"defintion: %@", defintion);
	
CFArrayRef utisRef = UTTypeCreateAllIdentifiersForTag(kUTTagClassFilenameExtension, (__bridge  CFStringRef)pathExtension, nil);
NSLog(@"UTI: utisRef %@", utisRef);
NSArray *utis = CFBridgingRelease(utisRef);
	
for (NSString *uti in utis) {
	CFDictionaryRef defintion = UTTypeCopyDeclaration((__bridge  CFStringRef)uti);
	NSDictionary *dict = CFBridgingRelease(defintion);
	NSLog(@"defintion: %@", dict);
}