NSString *initialString = @"Smash Bug! is a Great App! Have Fun with it!";
    NSURL *url = [NSURL URLWithString:@"https://itunes.apple.com/us/app/air-drum-*/id901397384?ls=1&mt=8"];
    //UIImage *showImage = [UIImage imageNamed:@"Default-568h@2x"];
    UIActivityViewController *activityViewController = [[UIActivityViewController alloc] initWithActivityItems:@[initialString,url] applicationActivities:nil];
    [self presentViewController:activityViewController animated:YES completion:nil];

至于要实现分享到朋友圈，QQ空间等，大家可以在网上找到相应的分享代码。

（2）评分

就是点击之后直接跳转到App Store，这个非常简单也非常重要：

NSString *str = @"itms-apps://ax.itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=901397384";
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];

大家在使用时把id改成自己应用的id就ok了。

（3）GameCenter

这个国内可能用得比较少，更喜欢微信之类，但在国外恐怕还是比较重要的一个方式。

这个大家得在iTunesConnect上启用GameCenter，并创建相应的LeaderShip和Achievement。

Raywenderlich上有相应的Tutorial。

而对于使用其实就两个流程：

（1）验证本地玩家，如果没登陆，弹出窗口登陆。

- (void)authenticateLocalPlayer
{
    GKLocalPlayer *localPlayer = [GKLocalPlayer localPlayer];
    
    localPlayer.authenticateHandler = ^(UIViewController *viewController,NSError *error) {
        //3
        [self setLastError:error];
        
        if (viewController != nil) {
            [self setAuthenticationViewController:viewController];
        } else if ([GKLocalPlayer localPlayer].isAuthenticated) {
            _enableGameCenter = YES;
        } else {
            _enableGameCenter = NO;
        }
    };
}

- (void)setAuthenticationViewController:(UIViewController *)authenticationViewController
{
    if (authenticationViewController != nil) {
        _authenticationViewController = authenticationViewController;
        [[NSNotificationCenter defaultCenter] postNotificationName:PresentAuthenticationViewController object:self];
    }
}

（2）实时发送分数等数据到GameCenter

2.1发送Achievement

创建Achievement成就的方法：

+ (GKAchievement *)reach10Achievement:(NSUInteger)numberOfReach
{
    CGFloat percent = numberOfReach/10 * 100.0;
    
    GKAchievement *reachAchievement = [[GKAchievement alloc] initWithIdentifier:kSmashBugReach10AchievementId];
    reachAchievement.percentComplete = percent;
    reachAchievement.showsCompletionBanner = YES;
    return reachAchievement;
    
}

发送成就

- (void)reportAchievements:(NSArray *)achievements
{
    if (!_enableGameCenter) {
        NSLog(@"Local play is not authenticated");
    }
    
    [GKAchievement reportAchievements:achievements withCompletionHandler:^(NSError *error) {
        [self setLastError:error];
    }];
}

2.2 发送得分等到LeaderShip（排行榜）

- (void)reportScore:(int64_t)score forLeaderboardID:(NSString *)leaderboardID
{
    if (!_enableGameCenter) {
        NSLog(@"Local Play is not authenticated");
    }
    
    GKScore *scoreRep
除此之外，我们还想点击GameCenter按钮之类显示GameCenter的界面：

orter = [[GKScore alloc] initWithLeaderboardIdentifier:leaderboardID];    scoreReporter.value = http://www.mamicode.com/score;    scoreReporter.context = 0;        NSArray *scores = @[scoreReporter];        [GKScore reportScores:scores withCompletionHandler:^(NSError *error) {        [self setLastError:error];    }];}

除此之外，我们还想点击GameCenter按钮之类显示GameCenter的界面：

- (void)showGKGameCenterViewController:(UIViewController *)viewController
{
    if (!_enableGameCenter) {
        NSLog(@"Local Play is not authenticated");
    }
    
    GKGameCenterViewController *gameCenterViewController = [[GKGameCenterViewController alloc] init];
    
    gameCenterViewController.gameCenterDelegate = self;
    
    gameCenterViewController.viewState = GKGameCenterViewControllerStateAchievements;
    
    [viewController presentViewController:gameCenterViewController animated:YES completion:nil];
}

    self.canDisplayBannerAds = YES;

// Admob
    [self addAdmob];

#pragma mark - Admob

- (void)addAdmob
{
    // Initialize the banner at the bottom of the screen.
    CGPoint origin = CGPointMake(0.0,
                                 self.view.frame.size.height -
                                 CGSizeFromGADAdSize(kGADAdSizeBanner).height);
    
    // Use predefined GADAdSize constants to define the GADBannerView.
    self.adBanner = [[GADBannerView alloc] initWithAdSize:kGADAdSizeBanner origin:origin];
    
    // Note: Edit SampleConstants.h to provide a definition for kSampleAdUnitID before compiling.
    self.adBanner.adUnitID = ADMOB_ID;
    self.adBanner.delegate = self;
    self.adBanner.rootViewController = self;
    [self.view addSubview:self.adBanner];
    [self.adBanner loadRequest:[self request]];
}

#pragma mark GADRequest generation

- (GADRequest *)request {
    GADRequest *request = [GADRequest request];
    
    // Make the request for a test ad. Put in an identifier for the simulator as well as any devices
    // you want to receive test ads.
    request.testDevices = @[
                            // TODO: Add your device/simulator test identifiers here. Your device identifier is printed to
                            // the console when the app is launched.
                            GAD_SIMULATOR_ID
                            ];
    return request;
}

#pragma mark GADBannerViewDelegate implementation

// We‘ve received an ad successfully.
- (void)adViewDidReceiveAd:(GADBannerView *)adView {
    NSLog(@"Received ad successfully");
}

- (void)adView:(GADBannerView *)view didFailToReceiveAdWithError:(GADRequestError *)error {
    NSLog(@"Failed to receive ad with error: %@", [error localizedFailureReason]);
}