讓特定物件跟著螢幕旋轉

有些遊戲（尤其是棋盤類）是背景不動，但是前景的物件都可以隨著持著機器的方式不同而做旋轉。
接下來，就來教這個做法：

使用code/lib：XCode 4、cocos2D 1.0.1


首先，先停止機器自己旋轉，在RootViewController.m下找到該function且改return值：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { 
  return NO;
}

再來是重頭戲，請到HelloWorld.m或是其他你要做這個功能的.m檔案中，在初始化的時候加上：

 [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:@"UIDeviceOrientationDidChangeNotification" object:nil];

之後再來添加orientationChanged:這個function即可，該function的寫法在下方<範例>中。


範例：

-(id)init{

    sp = [[CCSprite alloc] initWithFile:@"Play_Chess_B1.png"];
    sp.position = ccp(240,160);
    [self addChild:sp];


   [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:@"UIDeviceOrientationDidChangeNotification" object:nil];
   
   return self; 
}

-(void) orientationChanged:(NSNotification *)notification{

    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    //[UIApplication sharedApplication].statusBarOrientation
    CGFloat radian = 0; 
    switch (orientation) {
        case UIInterfaceOrientationPortrait:
            radian = -90;
            NSLog(@"轉啦！正常直向");
            break;
        case UIInterfaceOrientationPortraitUpsideDown:
            radian = 90;
            NSLog(@"轉啦！反直向");
            break;
        case UIInterfaceOrientationLandscapeLeft:
            radian = 180;
            NSLog(@"轉啦！按鈕左邊橫向");
            break;
        case UIInterfaceOrientationLandscapeRight:
            radian = 0;
            NSLog(@"轉啦！按鈕右邊橫向");
            break;
        default:
            break;
    }
 
    sp.rotation = radian;
}