如何复制当前活动的浏览器 URL？

我正在尝试获取活动浏览器窗口的当前活动浏览器 URL。有任何指针或代码示例吗？

Code:

NSAppleScript *script= [[NSAppleScript alloc] initWithSource:@"tell application \"Safari\" to return URL of front document as string"];
NSDictionary *scriptError = nil;
NSAppleEventDescriptor *descriptor = [script executeAndReturnError:&scriptError];
if(scriptError) {
    NSLog(@"Error: %@",scriptError);
} else {        
    NSAppleEventDescriptor *unicode = [descriptor coerceToDescriptorType:typeUnicodeText];
    NSData *data = [unicode data];
    NSString *result = [[NSString alloc] initWithCharacters:(unichar*)[data bytes] length:[data length] / sizeof(unichar)];
    NSLog(@"Result: %@",result);
}

Output:

Result: http://stackoverflow.com/questions/6111275/how-to-copy-the-current-active-browser-url/6111592#6111592