Something

	NSDictionary *attributes = [[NSDictionary alloc] initWithObjectsAndKeys:
		[NSFont fontWithName:@"Helvetica" size:12], NSFontAttributeName,
		[NSColor whiteColor], NSForegroundColorAttributeName, nil];
    
	NSAttributedString *myString = [[NSAttributedString alloc] 
		initWithString:@"hehehe" attributes: attributes];
								
	float stringHeight = [myString size].height;
	float stringWidth = [myString size].width;
	
	NSImage* anImage = [[NSImage alloc] initWithSize:NSMakeSize(stringHeight,  stringWidth)];

	[anImage lockFocus];
	[myString drawInRect:NSMakeRect(0,0, anImage.size.width, anImage.size.height) withAttributes:nil];
	[anImage unlockFocus];