If you will need launch AppStore application with search request – use this example
NSString *str = @"itms-apps://ax.search.itunes.apple.com";
    str = [NSString stringWithFormat:@"%@/WebObjects/MZSearch.woa/wa/search?media=software&term=", str];
    str = [NSString stringWithFormat:@"%@3d4medical", str];
   
    [[UIApplication sharedApplication] openURL: [NSURL URLWithString:str]];