ios 跳转app设置权限

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0) 
{
  NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
  if ([[UIApplication sharedApplication] canOpenURL:url])
  {
    [[UIApplication sharedApplication] openURL:url];
  }
}
else
{
}