选择 UICollectionView 中的单元格时调整图像大小

Question

我有一个 UICollectionview 和一个 imageview 在 cell.The UICollectionview 从照片库加载数据。当用户选择一个图像时，它需要传递给另一个 viewcontroller (NoteDetailViewController)。这是有效的。但是当传递给另一个 viewcontroller 时，图像清晰度会丢失。谁能帮我，如何修改 prepareForSegue 方法？

下面给出了相同的代码

import UIKit

import Photos

private let reuseIdentifier = "PhotoCell"

class AddPhotoViewController: UIViewController , UIImagePickerControllerDelegate ,UINavigationControllerDelegate ,UICollectionViewDataSource ,UICollectionViewDelegate
{

    @IBOutlet weak var photoAlbum: UICollectionView!

    var TakenImage : UIImageView!

    var assetCollection: PHAssetCollection!
    var photosAsset: PHFetchResult!
    var assetThumbnailSize: CGSize!
    let imagePicker: UIImagePickerController! = UIImagePickerController()
    var cameraon : Bool = false

    override func viewDidLoad()
    {
        super.viewDidLoad()

        let collection:PHFetchResult = PHAssetCollection.fetchAssetCollectionsWithType(.SmartAlbum, subtype: .SmartAlbumUserLibrary, options: nil)

        var i = 0
        repeat
        {
            if let first_Obj:AnyObject = collection.objectAtIndex(i)
            {
                self.assetCollection = first_Obj as! PHAssetCollection
            }
            i++
        }while( i < collection.count)



        // Do any additional setup after loading the view.
    }

    @IBAction func takePhoto(sender: AnyObject) {
        if (UIImagePickerController.isSourceTypeAvailable(.Camera)) {
            if UIImagePickerController.availableCaptureModesForCameraDevice(.Rear) != nil {
                imagePicker.allowsEditing = false
                imagePicker.sourceType = .Camera
                imagePicker.cameraCaptureMode = .Photo
                presentViewController(imagePicker, animated: true, completion: {})
                cameraon = true
            } else {
                print("Rear camera doesn't exist")
            }
        } else {
            print("Camera inaccessable")
        }

    }
    func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
        TakenImage.image  = image
        if (cameraon)
        {
            let imageData = UIImageJPEGRepresentation(TakenImage.image!, 0.6)
            let compressedJPGImage = UIImage(data: imageData!)
            UIImageWriteToSavedPhotosAlbum(compressedJPGImage!, nil, nil, nil)

        }
        self.dismissViewControllerAnimated(true, completion: nil)
    }


    func imagePickerControllerDidCancel(picker: UIImagePickerController) {
        print("User canceled image")
        dismissViewControllerAnimated(true, completion: {
            // Anything you want to happen when the user selects cancel
        })
    }


    override func viewWillAppear(animated: Bool)
    {
        if let layout = self.photoAlbum!.collectionViewLayout as? UICollectionViewFlowLayout{
            let cellSize = layout.itemSize

            self.assetThumbnailSize = CGSizeMake(cellSize.width, cellSize.height)
        }

        //fetch the photos from collection
        self.photosAsset = PHAsset.fetchAssetsInAssetCollection(self.assetCollection, options: nil)

        self.photoAlbum!.reloadData()


    }

    // MARK: UICollectionViewDelegate

    /*
    // Uncomment this method to specify if the specified item should be selected
    override func collectionView(collectionView: UICollectionView, shouldSelectItemAtIndexPath indexPath: NSIndexPath) -> Bool {
    return true
    }
    */


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
    {
        if (segue.identifier == "savePhoto")
        {
            if let controller : NoteDetailViewController = segue.destinationViewController as? NoteDetailViewController
            {
                controller.imageView.image = TakenImage.image
            }
        }
        if (segue.identifier == "saveSelected")
        {
            if let controller:NoteDetailViewController = segue.destinationViewController as? NoteDetailViewController
            {
                if let cell = sender as? PhotoAlbumCollectionViewCell
                {
                        let imageToPass = cell.imageView.image

                        controller.someImage = imageToPass

                }
            }
        }
    }


    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int
    {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }

    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        // #warning Incomplete implementation, return the number of items
        var count: Int = 0

        if(self.photosAsset != nil){
            count = self.photosAsset.count
        }
        print("\(self.photosAsset.count)")
        return count
    }
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell
    {
        let cell: PhotoAlbumCollectionViewCell = photoAlbum.dequeueReusableCellWithReuseIdentifier("PhotoCell", forIndexPath: indexPath) as! PhotoAlbumCollectionViewCell

        //Modify the cell
        let asset: PHAsset = self.photosAsset[indexPath.item] as! PHAsset

        PHImageManager.defaultManager().requestImageForAsset(asset, targetSize: self.assetThumbnailSize, contentMode: .AspectFill, options: nil, resultHandler: {(result, info)in
            if let image = result {
                cell.setThumbnailImage(image)
            }
        })

        return cell
    }



    func collectionView(collectinView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAtIndex section: Int) -> CGFloat {
        return 4
    }

    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAtIndex section: Int) -> CGFloat {
        return 1
    }

    func collectionView(collectionView: UICollectionView, shouldShowMenuForItemAtIndexPath indexPath: NSIndexPath) -> Bool {
        return false
    }

    func collectionView(collectionView: UICollectionView, canPerformAction action: Selector, forItemAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) -> Bool {
        return false
    }

    func collectionView(collectionView: UICollectionView, performAction action: Selector, forItemAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) {

        self.dismissViewControllerAnimated(false, completion: nil)

    }

}

Answer 1

首先，您要求 targetSize 是 cellForRowAtIndexPath 中的缩略图之一。现在在 prepareForSegue 中，您需要再次向 PHImageManager 询问资产，但现在使用更大的 TargetSize，它可以满足您的需求您可以向 collectionView 询问 indexPathsForSelectedItems()，您可以使用它来了解用户选择了哪个资产

if (segue.identifier == "saveSelected")
    {
        if let controller:NoteDetailViewController = segue.destinationViewController as? NoteDetailViewController
        {
            if let cell = sender as? PhotoAlbumCollectionViewCell
            {
                let asset: PHAsset = self.photosAsset[indexPath.item] as! PHAsset

                PHImageManager.defaultManager().requestImageForAsset(asset, targetSize: controller.view.size, contentMode: .AspectFill, options: nil, resultHandler: {(result, info)in
                    if let image = result {
                        cell.setThumbnailImage(image)
                    }
                })

                    controller.someImage = imageToPass

            }
        }
    }

选择 UICollectionView 中的单元格时调整图像大小

Resizing an image when the cell in a UICollectionView is selected

photos

ios

uicollectionview

swift