如何刷新collectionView

时间:2018-10-16 12:38:50

标签: ios swift uicollectionview

我的问题是,当我将图片保存到照片库时,我的collectionView不会更新。如果我单击第一张图片,它将打开我最近保存的图片,但从外观上来说,collectionView不会更新。我以为reloadData()可以这样工作,但我猜不是这样。

在应用加载时,用户从collectionView(iPhone照片库)中选择照片,然后将其发送到另一个视图,在该视图中,他将照片编辑,然后将其保存到图库中,并使用展开按钮返回到第一个视图。

我的代码:

class pickerViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

    var activityIndicator:UIActivityIndicatorView = UIActivityIndicatorView()

    var imageArray = [UIImage]()


    override func viewDidLoad() {
        mygtukasMenu.layer.cornerRadius = 10
        mygtukasMenu.clipsToBounds = true
        grabPhotos()
        kolekcija.reloadData()
    }

    @IBOutlet weak var kolekcija: UICollectionView!
    func grabPhotos(){

        let imgManager = PHImageManager.default()

        let requestOptions = PHImageRequestOptions()
        requestOptions.isSynchronous = false
        requestOptions.deliveryMode = .opportunistic // Quality of images
        requestOptions.isNetworkAccessAllowed = true

        requestOptions.isSynchronous = true
        requestOptions.progressHandler = {  (progress, error, stop, info) in
            print("progress: \(progress)")
        }

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





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

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

                    imgManager.requestImage(for: fetchResult.object(at: i) , targetSize: CGSize(width: 150, height: 150), contentMode: .aspectFill, options: requestOptions, resultHandler: {
                        image, error in
                        self.imageArray.append(image!)


                    })
                }
            }
            else {
                print("You got no photos")
                kolekcija.reloadData()
            }
        }
        kolekcija.reloadData() // UPDATED
    }


    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        grabPhotos()
        kolekcija.reloadData() // UPDATED
    }


}

2 个答案:

答案 0 :(得分:1)

当您在块中的funcgrabPhotos()获取图片时,您需要调用reloadData()

imgManager.requestImage(for: fetchResult.object(at: i) , targetSize: CGSize(width: 150, height: 150), contentMode: .aspectFill, options: requestOptions, resultHandler: {
                    image, error in
                    self.imageArray.append(image!)
                    self.kolekcija.reloadData() <<<<< HERE RELOAD CALL NEED
                })

打电话时

override func viewDidLoad() {
    mygtukasMenu.layer.cornerRadius = 10
    mygtukasMenu.clipsToBounds = true
    grabPhotos() <<< photos still grabbing at async mode
    kolekcija.reloadData() <<< there is no images grabbed... it still grabbing at async mode when u call reload func here.....
}

答案 1 :(得分:0)

我的问题的解决方案是每次加载视图时从imageArray中删除所有图像。我不知道为什么它这么重要,但终于奏效了。而且,无需在requestImage块内调用reloadData()。 (以我为例)

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.imageArray.removeAll()
    grabPhotos()
    kolekcija.reloadData()
}