方法一:

[[UIApplicationsharedApplication] openURL:[NSURLURLWithString:@"https://itunes.apple.com/cn/app/xxxx"]];

方法二:(推荐)

添加StoreKit,framework系统库，实现相应的代理方法

SKStoreProductViewController*store = [[SKStoreProductViewControlleralloc] init];

store.delegate =self;

[store loadProductWithParameters://appId唯一的

@{SKStoreProductParameterITunesItemIdentifier:@"appid"} completionBlock:^(BOOL  result,NSError*error) {

} }]

//取消代理

- (void)productViewControllerDidFinish:(SKStoreProductViewController*)viewController{    

];}