Вы можете открыть приложение, не открывая Safari
NSString *appId = @"you appid"; //like 999999999
NSString *link = [@"itms-apps://ax.itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=" stringByAppendingString:appId];
[[UIApplication sharedApplication] openURL: [NSURL URLWithString:link]];