快速旋转 UIColectionView 时的水平滚动

Question

我正在尝试快速构建collectionView，我希望当设备处于纵向时collectionView 垂直滚动，而当我在横向模式下旋转设备时collectionView 水平滚动。这是CollectionView 类：

class SceneBuilderVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource{
    @IBOutlet var collection: UICollectionView!

    override func viewDidLoad() {
       super.viewDidLoad()
    }

    override func shouldAutorotate() -> Bool{
       return true
    }

    override func supportedInterfaceOrientations() -> Int{
        return Int(UIInterfaceOrientationMask.All.toRaw())
    }

    func numberOfSectionsInCollectionView(collectionView: UICollectionView!) -> Int {
        return 1;
    }

    func collectionView(collectionView: UICollectionView!, numberOfItemsInSection section: Int) -> Int {
           return 50;
    }

    func collectionView(collectionView: UICollectionView!, cellForItemAtIndexPath indexPath: NSIndexPath!) -> UICollectionViewCell!{
        var cell:UICollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath) as UICollectionViewCell
        cell.backgroundColor = UIColor.redColor()
        return cell
    }
}

要更改滚动方向，我需要更改 collectionView 布局。

var flowLayout:UICollectionViewFlowLayout = UICollectionViewFlowLayout()
var scrollDirection = UICollectionViewScrollDirection.Vertical
flowLayout.scrollDirection = scrollDirection
self.collection.collectionViewLayout = flowLayout

另外，在 iOS8 中，Apple 将屏幕旋转方式 willRotateToInterfaceOrientation:duration 改为 viewWillTransitionToSize:withTransitionCoordinator

如何使用 **viewWillTransitionToSize:withTransitionCoordinator* 方法检查设备何时旋转并因此更改滚动方向？

Answer 1

使用 animateAlongsideTransition 中的完成处理程序检查旋转后的方向并进行任何调整。

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransitionToSize(size, withTransitionCoordinator: coordinator)
    coordinator.animateAlongsideTransition(nil, completion: {context in
        if(UIDevice.currentDevice().orientation == UIDeviceOrientation.Portrait || UIDevice.currentDevice().orientation == UIDeviceOrientation.PortraitUpsideDown){
            //this is portrait (or upsidedown), do something
        }else{
            //landscape 
        }
    })
}

但除非在特殊情况下，您不应该真正关心设备的确切方向，您可以简单地将视图调整为“新尺寸”

Answer 2

选项 #1：

如果您的集合视图占据了整个屏幕，那么您可以简单地检查宽度是否大于高度并将结果作为横向。

选项 #2：

或者你可以使用函数：

UIInterfaceOrientationIsLandscape(self.interfaceOrientation) 

但你应该知道 interfaceOrientation 属性在 iOS8 中已被弃用。

Answer 3

这就是完整的功能：

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator   coordinator: UIViewControllerTransitionCoordinator!){
    if let theAppDelegate = UIApplication.sharedApplication() {
        let orientation = theAppDelegate.statusBarOrientation
        if orientation.isPortrait {
            println("Landscape")
            var flowLayout:UICollectionViewFlowLayout = UICollectionViewFlowLayout()
            //flowLayout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
            //flowLayout.itemSize = CGSizeMake(80, 80)
            var scrollDirection = UICollectionViewScrollDirection.Horizontal
            flowLayout.scrollDirection = scrollDirection
            self.collection.collectionViewLayout = flowLayout
        }else{
            println("Protrait")
            var flowLayout:UICollectionViewFlowLayout = UICollectionViewFlowLayout()
            // flowLayout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
            //flowLayout.itemSize = CGSizeMake(80, 80)
            var scrollDirection = UICollectionViewScrollDirection.Vertical
            flowLayout.scrollDirection = scrollDirection
            self.collection.collectionViewLayout = flowLayout
        }
    }
}