ios - 当我在 swift 3 中从图库中获取照片时，为什么收藏视图为空？

Question

我正在使用 swift 3 并希望在收藏视图中查看照片库图像但这些代码对我不起作用

在看到我的代码之前注意这一点：**我不会收到任何错误或崩溃我只是在收藏视图中看不到我的任何图像库**这是我的代码：

  import UIKit
  import Photos

 class collectionImageViewController: UIViewController , UICollectionViewDataSource , UICollectionViewDelegate {

var imageArray = [UIImage]()

@IBOutlet weak var collectionImageView: UICollectionView!

override func viewDidLoad() {
    super.viewDidLoad()

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



func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return imageArray.count
}


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewImageCell", for: indexPath) as! CollectionViewImageCell

    cell.theImage.image = imageArray[indexPath.row]

    return cell
}

func getPhotosFromAlbum() {

    let imageManager = PHImageManager.default()

    let requestOptions = PHImageRequestOptions()
    requestOptions.isSynchronous = true
    requestOptions.deliveryMode = .highQualityFormat

    let fetchOptions = PHFetchOptions()
    fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]

    let fetchResult: PHFetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)

    if fetchResult.count > 0 {

        for i in 0..<fetchResult.count {

            imageManager.requestImage(for: fetchResult.object(at: i), targetSize: CGSize(width: 300, height: 300), contentMode: .aspectFill, options: requestOptions, resultHandler: { image, error in

                self.imageArray.append(image!)
            })
        }
    } else {
        self.collectionImageView?.reloadData()
    }


}

Answer 1

这是我从画廊加载所有图像并加载到collectioview的整个代码。请看这段代码

import UIKit
import Photos
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    let arr_img = NSMutableArray()
    @IBOutlet var collview: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()
        let allPhotosOptions : PHFetchOptions = PHFetchOptions.init()
        allPhotosOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
        let allPhotosResult = PHAsset.fetchAssets(with: .image, options: allPhotosOptions)
        allPhotosResult.enumerateObjects({ (asset, idx, stop) in

            self.arr_img.add(asset)
        })

    }
    func getAssetThumbnail(asset: PHAsset, size: CGFloat) -> UIImage {
        let retinaScale = UIScreen.main.scale
        let retinaSquare = CGSize(width: size * retinaScale, height: size * retinaScale)//CGSizeMake(size * retinaScale, size * retinaScale)
        let cropSizeLength = min(asset.pixelWidth, asset.pixelHeight)
        let square = CGRect(x: 0, y: 0, width: cropSizeLength, height: cropSizeLength)//CGRectMake(0, 0, CGFloat(cropSizeLength), CGFloat(cropSizeLength))
        let cropRect = square.applying(CGAffineTransform(scaleX: 1.0/CGFloat(asset.pixelWidth), y: 1.0/CGFloat(asset.pixelHeight)))

        let manager = PHImageManager.default()
        let options = PHImageRequestOptions()
        var thumbnail = UIImage()

        options.isSynchronous = true
        options.deliveryMode = .highQualityFormat
        options.resizeMode = .exact
        options.normalizedCropRect = cropRect

        manager.requestImage(for: asset, targetSize: retinaSquare, contentMode: .aspectFit, options: options, resultHandler: {(result, info)->Void in
            thumbnail = result!
        })
        return thumbnail
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    //MARK:
    //MARK: Collectioview methods
    func collectionView(_ collectionView: UICollectionView,
                        numberOfItemsInSection section: Int) -> Int {
        return arr_img.count
    }
    func collectionView(_ collectionView: UICollectionView,
                        cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell",
                                                      for: indexPath)
        let imgview : UIImageView = cell.viewWithTag(20) as! UIImageView
        imgview.image = self.getAssetThumbnail(asset: self.arr_img.object(at: indexPath.row) as! PHAsset, size: 150)

        return cell
    }

}

Answer 2

您必须像这样在 for 循环之后重新加载 collectionView

  ...
{
    for i in 0..<fetchResult.count {

                imageManager.requestImage(for: fetchResult.object(at: i), targetSize: CGSize(width: 300, height: 300), contentMode: .aspectFill, options: requestOptions, resultHandler: { image, error in

                    self.imageArray.append(image!)
                })
    self.collectionImageView?.reloadData()

}
    ...