如何在ios中获取手机中的所有图像

Question

我想从手机中获取所有图像。在照片库中创建多个选项。我使用下面的代码从手机中获取所有图像。它工作得很好，但是当在手机上有1000张图像时，它需要更多时间来获取所有图像并在视图中显示。如何减少从手机获取所有图像的时间。

 // get all images from photos
    func getAllImagesFromPhotos() -> [Photos]?
    {

        let imgManager = PHImageManager.default()
        let requestOptions = PHImageRequestOptions()
        requestOptions.isSynchronous = true
        let fetchOptions = PHFetchOptions()
        fetchOptions.sortDescriptors = [NSSortDescriptor(key:"creationDate", ascending: true)]

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

        var allImages = [Photos]()

        for index in 0..<fetchResult.count
        {
            let asset = fetchResult.object(at: index) as PHAsset
            imgManager.requestImage(for: asset, targetSize: CGSize(width:200,height:200), contentMode: .aspectFill, options: requestOptions, resultHandler: { (uiimage, info) in
                if let image = uiimage
                {
                    allImages.append(Photos(image: image, selected: false))
                }
            })
        }

        return allImages
    }