获取屏幕旋转的通知

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： [iOS]关于iOS中界面视图横屏/竖屏切换的问题总结：http://blog.csdn.net/lqq200912408/article/details/51088987