Mac Geekery

Answer

There exists no tool to do this. So I wrote one.

The following is released under the one, true open source license: MIT.

//	Copyright© 2007 Adam Knight

//

//	Permission is hereby granted, free of charge, to any person obtaining a

//	copy of this software and associated documentation files (the

//	“Software”), to deal in the Software without restriction, including

//	without limitation the rights to use, copy, modify, merge, publish,

//	distribute, sublicense, and/or sell copies of the Software, and to

//	permit persons to whom the Software is furnished to do so, subject to

//	the following conditions:

//

//	The above copyright notice and this permission notice shall be included

//	in all copies or substantial portions of the Software.

//

//	THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS

//	OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

//	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

//	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

//	CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

//	TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

//	SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


	
#import 
#include 

	
void usage() {
	printf(“usage: SetFile -i image target\n”);
	exit(EXIT_FAILURE);

}

	
int main (int argc, char * argv[]) {
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
	char option;
	NSString *sourceFile = nil;
	NSString *targetFile = nil;
	BOOL result;
	
	while ((option = getopt(argc, argv, “i:”)) != -1) {
		switch (option) {
			case ‘i’:
				sourceFile = [NSString stringWithCString:optarg];
				break;
			default:
				usage();
				break;
		}
	}
	
	if (optind < argc)
		targetFile = [NSString stringWithCString:(char*)argv[optind]];
	else
		usage();
	
	// Begin
	result = [[NSFileManager defaultManager] fileExistsAtPath:sourceFile];

	
	if (!result) {
		printf(“file does not exist: %s\n”, [sourceFile cString]);
		exit(EXIT_FAILURE);
	}

	
	NSImage *icon = [[[NSImage alloc] initWithContentsOfFile:sourceFile] autorelease];
	
	if (!icon) {
		printf(“file is not a valid image file: %s\n”, [sourceFile cString]);
		exit(EXIT_FAILURE);
	}
	
	result = [[NSFileManager defaultManager] fileExistsAtPath:targetFile];

	
	if (!result) {
		printf(“file does not exist: %s\n”, [targetFile cString]);
		exit(EXIT_FAILURE);
	}
	
	result = [[NSWorkspace sharedWorkspace] setIcon:icon forFile:targetFile options:nil];

	
	if (!result) {
		printf(“failed to set icon for file: %s\n”, [targetFile cString]);
		exit(EXIT_FAILURE);
	}
	
	[pool release];
    return 0;

}

What does all that do? It reads any graphic format that Preview can read (yes, even PDF) and then sets the icon of the file to that graphic, doing the proper conversions for you. Ain’t Cocoa grand?

You would compile the above into a universal tool like so:

$ gcc -arch i386 -arch ppc -framework AppKit -o SetIcon SetIcon.m

You’ll likely need someone logged in for this to work, as NSWorkspace generally requires that.

The source and universal binary are below.