[[NSNotificationCenter defaultCenter] addObserver:self
    selector:@selector(changeFrames:)                           
  name:UIDeviceOrientationDidChangeNotification
     object:nil];  

-(void)changeFrames:(NSNotification *)notification{
  NSLog(@"change notification: %@", notification.userInfo);
  float width=[[UIScreen mainScreen]bounds].size.width*[[UIScreen mainScreen] scale];
  float height=[[UIScreen mainScreen]bounds].size.height*[[UIScreen mainScreen] scale];
  if ([[UIDevice currentDevice] orientation]==UIInterfaceOrientationPortrait
    || [[UIDevice currentDevice] orientation]==UIInterfaceOrientationPortraitUpsideDown) {
    NSLog(@">>>portrait");
    self.frame=CGRectMake(0, 0, height, width);
  }else{
    NSLog(@">>>landscape");
    self.frame=CGRectMake(0, 0, width, height);
  }
  
  NSLog(@"view—> %@",self);
}

 //得到当前屏幕的尺寸：
  CGSize size_screen = [[UIScreenmainScreen]bounds].size;
  //获得缩放率：
  CGFloat scale_screen = [UIScreen mainScreen].scale;  

  此时屏幕尺寸的宽高与scale的乘积就是相应的分辨率值。
  CGRect sizeOfA4 = CGRectMake(0, 0, 595, 842);//生成PDF文件时按A4标准
  CGRect sizeOfA5 = CGRectMake(0, 0, 421, 595);//生成PDF文件时按A5标准

 #if defined(TARGET_IPHONE_SIMULATOR) && TARGET_IPHONE_SIMULATOR
    NSLog(@" on simulator");
 #else
    NSLog(@"not on simulator");
#endif

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
      //设备为ipad
    } else {
      //设备为iphone 或 ipod
    }

 NSString *deviceType = [UIDevice currentDevice].model;  
    if([deviceType isEqualToString:@"iPhone"]) {
       //iPhone
    }else if([deviceType isEqualToString:@"iPod touch"]) {
      //iPod Touch
    }else {
      //iPad
    }

  //软件信息
  NSLog(@"sysname=%@",[[UIDevice currentDevice] systemName]);// 系统名
  NSLog(@"systemVersion=%@",[[UIDevice currentDevice] systemVersion]); //版本号
  NSLog(@"model=%@",[[UIDevice currentDevice] model]); //类型（ipad、ipod、iphone）而[[UIDevice currentDevice] userInterfaceIdiom]只能判断iphone和ipad
  NSLog(@"olduuid=%@",[[UIDevice currentDevice] uniqueIdentifier]); //唯一识别码 ios5.0开始deprecated
  NSLog(@"name=%@",[[UIDevice currentDevice] name]); //设备名称
  NSLog(@"localizedModel=%@",[[UIDevice currentDevice] localizedModel]); // 本地模式
  NSLog(@"ios6UUID=%@",[[[UIDevice currentDevice] identifierForVendor] UUIDString]);//ios6.0开始available
  
  ----------注：以下内容未测试---------------
  // 硬件信息
  [UIDevice platform];//平台
  [UIDevice cpuFrequency]];//cpu信息
  UIDevice busFrequency]];//总线
  [UIDevice totalMemory]];//总内存
  UIDevice userMemory]];//已经使用的内存
  -----------------------------------------------------------------------------------------------------------------------------
  //App信息
  NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];
  CFShow(infoDictionary);//所有plist内容
  // app名称
  NSString *app_Name = [infoDictionary objectForKey:@"CFBundleDisplayName"];
  // app版本
  NSString *app_Version = [infoDictionary objectForKey:@"CFBundleShortVersionString"];
  // app build版本
  NSString *app_build = [infoDictionary objectForKey:@"CFBundleVersion"];
 
  //判断是否有照相机
  if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) 
    NSLog(@"有");
  else
    NSLog(@"没有");