NSDocumentController+DisambiguateForUTI.m

#import "NSDocumentController+DisambiguateForUTI.h"
#import "NSBundle+MainApp.h"
#import "NSArray+SafeGetters.h"
#import "NSBundle+MainApp.h"

@implementation NSDocumentController (DisambiguateForUTI)

- (NSString*)filenameExtensionForDocumentUTI:(NSString*)uti {
	NSArray* docDics = [[NSBundle mainAppBundle] objectForInfoDictionaryKey:@"CFBundleDocumentTypes"] ;
	NSString* extension = nil ;
	for (NSDictionary* docDic in docDics) {
		NSArray* utis = [docDic objectForKey:@"LSItemContentTypes"] ;
		for (NSString* uti in utis) {
			if ([uti isEqualToString:uti]) {
				NSArray* extensions = [docDic objectForKey:@"CFBundleTypeExtensions"] ;
				extension = [extensions firstObjectSafely] ;
				break ;
			}
		}
		if (extension) {
			break ;
		}
	}
					
	return extension ;
}			

- (NSString*)displayNameForDocumentUTI:(NSString*)uti {
	NSArray* docDics = [[NSBundle mainAppBundle] objectForInfoDictionaryKey:@"CFBundleDocumentTypes"] ;
	NSString* displayName = nil ;
	for (NSDictionary* docDic in docDics) {
		NSArray* utis = [docDic objectForKey:@"LSItemContentTypes"] ;
		for (NSString* uti in utis) {
			if ([uti isEqualToString:uti]) {
				displayName = [docDic objectForKey:@"CFBundleTypeName"] ;
				break ;
			}
		}
		if (displayName) {
			break ;
		}
	}
	
	return displayName ;
}			

- (NSDictionary *)defaultDocumentInfo {
    // If this executable is located in Contents/MacOS, then -[NSDocumentController defaultType]
	// will return the UTI instead of the "Name" if the document type has a UTI defined.
	// NSString* uti = [self defaultType] ;
	
	// Unfortunately, if this executable is not in Contents/MacOS, as occurs if executing
	// a helper application, which is located in Contents/Helpers/, for other reasons,
	// -[NSDocumentController defaultType] will return nil.
    //  The solution is to to dig into the mainAppBundle ourselves
    NSArray* docDics = [[NSBundle mainAppBundle] objectForInfoDictionaryKey:@"CFBundleDocumentTypes"] ;
    return [docDics firstObjectSafely] ;
}

- (NSString*)defaultDocumentUTI {
    NSDictionary *docInfo = [self defaultDocumentInfo] ;
    NSArray* utis = [docInfo objectForKey:@"LSItemContentTypes"] ;
    NSString* uti = [utis firstObjectSafely] ;

	return uti ;
}

- (NSString*)defaultDocumentFilenameExtension {
	NSString* uti = [self defaultDocumentUTI] ;
	return [self filenameExtensionForDocumentUTI:uti] ;
}

- (NSString*)defaultDocumentDisplayName {
	NSString* uti = [self defaultDocumentUTI] ;
	return [self displayNameForDocumentUTI:uti] ;
}

- (Class)defaultDocumentClass {
    NSString* string = [[self defaultDocumentInfo] objectForKey:@"NSDocumentClass"] ;
    return NSClassFromString(string) ;
}

- (NSString*)defaultDocumentIconName {
    return [[self defaultDocumentInfo] objectForKey:@"CFBundleTypeIconFile"] ;
}

- (NSImage*)defaultDocumentImage {
    NSString* imageName = [self defaultDocumentIconName] ;
    NSBundle* bundle = [NSBundle mainBundle] ;
    NSImage* image ;
    if ([bundle respondsToSelector:@selector(imageForResource:)]) {
        // macOS 10.7 or later can extract an image from a icon (.icns) file.
#pragma deploymate push "ignored-api-availability" // Skip it until next "pop"
        image = [bundle imageForResource:imageName] ;
#pragma deploymate pop
    }
    else {
        // macOS 10.6
        // You must provide a png file.  Or maybe you could leave ofType = nil,
        // but I'm not sure if an .icns would interfere with that.  Definitely,
        // macOS 10.6 fails to get the image if you only provide a .icns.
        NSString* imagePath = [bundle pathForResource:imageName
                                               ofType:@"png"] ;
        image = [[NSImage alloc] initByReferencingFile:imagePath] ;
        [image autorelease] ;
    }
    return image ;
}

@end