<分区>
当我试图从我的图库中获取 10 张图片时，我需要很长时间才能获取。
- 为什么图像获取是异步的？
- 如果我将 requestOptions.deliveryMode 更改为 .fastFormat，它会变得很快，但我会失去质量
我能做的最好的是什么？
func fetchPhotos() {
let fetchOptions = PHFetchOptions()
fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
fetchOptions.fetchLimit = 10
let fetchResult: PHFetchResult = PHAsset.fetchAssets(with: PHAssetMediaType.image, options: fetchOptions)
if fetchResult.count > 0 {
let totalImageCountNeeded = 10 // <-- The number of images to fetch
fetchPhotoAtIndex(0, totalImageCountNeeded, fetchResult)
}
}
func fetchPhotoAtIndex(_ index:Int, _ totalImageCountNeeded: Int, _ fetchResult: PHFetchResult<PHAsset>) {
let requestOptions = PHImageRequestOptions()
requestOptions.deliveryMode = .highQualityFormat
PHImageManager.default().requestImage(for: fetchResult.object(at: index) as PHAsset, targetSize: view.frame.size, contentMode: PHImageContentMode.aspectFill, options: requestOptions, resultHandler: { (image, _) in
if let image = image {
// Add the returned image to your array
self.images += [image]
}
if index + 1 < fetchResult.count && self.images.count < totalImageCountNeeded {
self.fetchPhotoAtIndex(index + 1, totalImageCountNeeded, fetchResult)
} else {
print("Completed array: \(self.images)")
self.collectionView.reloadData()
}
})
}