在viewcontroller里加上这句：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(statusBarOrientationChange:)                                        name:UIDeviceOrientationDidChangeNotification object:nil];//屏幕旋转的通知

在通知的方法里加上这句：

-(void)statusBarOrientationChange:(NSNotification*)no{    NSDictionary* ntfDict = [no userInfo];    self.collectionView.frame = CGRectMake(0, 0, DF_WIDTH, DF_HEIGHT);//如果要重置view的大小的话，一定要加上这句    UIDeviceOrientation interfaceOrientation = [UIDevice currentDevice].orientation;        if (interfaceOrientation == UIDeviceOrientationPortrait || interfaceOrientation == UIDeviceOrientationPortraitUpsideDown) {            //翻转为竖屏时            count = 3;            [self.collectionView reloadData];            }else if (interfaceOrientation==UIDeviceOrientationLandscapeLeft || interfaceOrientation == UIDeviceOrientationLandscapeRight) {            //翻转为横屏时            count = 5;            [self.collectionView reloadData];        }}

更全总结： ：http://blog.csdn.net/lqq200912408/article/details/51088987