Select an image file using a sheet in Cocoa

gistfile1.m

NSArray *allowedImageFileExtensions = [NSArray arrayWithObjects:@"png",@"jpg",@"jpeg",@"gif",@"bmp",nil];

// ...

- (IBAction)displayImagePickerSheet:(id)sender {
	NSOpenPanel *panel = [NSOpenPanel openPanel];
	[panel setAllowedFileTypes:allowedImageFileExtensions];
	[panel setDirectory:NSHomeDirectory()];
	[panel setAllowsMultipleSelection:NO];
	[panel setCanChooseDirectories:NO];
	[panel setCanChooseFiles:YES];
	[panel setResolvesAliases:YES];
	
	[panel beginSheetModalForWindow:window completionHandler:^(NSInteger result) {
		if (result == NSFileHandlingPanelOKButton) {
			// We aren't allowing multiple selection, but NSOpenPanel still returns
			// an array with a single element.
			NSURL *imagePath = [[panel URLs] objectAtIndex:0];
			NSImage *image = [[NSImage alloc] initWithContentsOfURL:imagePath];
			NSLog(@"Image: %@", image);
			[image release];
		} else {
			[panel close];
		}

	}];
}

[panel setAllowedFileTypes:[NSImage imageFileTypes]];