直接代码

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0) {
        NSString *str = [NSString stringWithFormat:@"itms-apps://itunes.apple.com/app/idxxxxxxx"];
        
        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];

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