我需要在 viewDidload
事件中从照片库中获取并显示最后拍摄的 3 张照片,而无需任何点击.
I need to get and show last taken 3 photos from photo library on viewDidload
event without any clicks.
在这一步之后,当我滚动 ScrollView
时,我应该得到其他 3 张 3 的照片.
After this step, I should get other photos 3 by 3 when I scroll the ScrollView
.
您知道使用 swift 执行此操作的正确方法吗?谢谢.
Do you know the proper way to do this with swift? Thanks.
这是一个使用 iOS 8+ 设备可用的 Photos
框架的解决方案:
Here's a solution using the Photos
framework available for devices iOS 8+ :
import Photos
class ViewController: UIViewController {
var images:[UIImage] = []
func fetchPhotos () {
// Sort the images by descending creation date and fetch the first 3
let fetchOptions = PHFetchOptions()
fetchOptions.sortDescriptors = [NSSortDescriptor(key:"creationDate", ascending: false)]
fetchOptions.fetchLimit = 3
// Fetch the image assets
let fetchResult: PHFetchResult = PHAsset.fetchAssets(with: PHAssetMediaType.image, options: fetchOptions)
// If the fetch result isn't empty,
// proceed with the image request
if fetchResult.count > 0 {
let totalImageCountNeeded = 3 // <-- The number of images to fetch
fetchPhotoAtIndex(0, totalImageCountNeeded, fetchResult)
}
}
// Repeatedly call the following method while incrementing
// the index until all the photos are fetched
func fetchPhotoAtIndex(_ index:Int, _ totalImageCountNeeded: Int, _ fetchResult: PHFetchResult<PHAsset>) {
// Note that if the request is not set to synchronous
// the requestImageForAsset will return both the image
// and thumbnail; by setting synchronous to true it
// will return just the thumbnail
let requestOptions = PHImageRequestOptions()
requestOptions.isSynchronous = true
// Perform the image request
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 you haven't already reached the first
// index of the fetch result and if you haven't
// already stored all of the images you need,
// perform the fetch request again with an
// incremented index
if index + 1 < fetchResult.count && self.images.count < totalImageCountNeeded {
self.fetchPhotoAtIndex(index + 1, totalImageCountNeeded, fetchResult)
} else {
// Else you have completed creating your array
print("Completed array: (self.images)")
}
})
}
}
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