ios判断设备是iphone还是ipad

在ios开发的过程中，有可能这里应用在iphone和ipad上都要使用，但是怎么判断当前设备是iphone还是ipad呢，在这里提供一种方法来判断这个设备是什么设备，具体代码如下
?
    NSString *nibTitle = @"PadContent"; //默认是ipad
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
    { //如果当前设备是iphone 就改为iphone的nib文件
        nibTitle = @"PhoneContent";
    }
    [[NSBundle mainBundle] loadNibNamed:nibTitle owner:self options:nil];//加载nib

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController_iPhone"bundle:nil] autorelease];
    } else {
        self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController_iPad"bundle:nil] autorelease];
    }
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    return YES;
}