我正在将用户相册中的照片加载到 Collection View 中,类似于 this Apple Sample project 中的操作。 .我似乎无法追查为什么内存增长失控。我使用建议的 PHCachingImageManager但所有这些结果都是图像模糊、滚动卡住和内存增长失控,直到应用程序崩溃。
在我的 viewDidLoad
中,我运行下面的代码
PHPhotoLibrary.requestAuthorization { (status: PHAuthorizationStatus) in
print("photo authorization status: \(status)")
if status == .authorized && self.fetchResult == nil {
print("authorized")
let fetchOptions = PHFetchOptions()
fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
var tempArr:[PHAsset] = []
self.fetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)
guard let fetchResult = self.fetchResult else{
print("Fetch result is empty")
return
}
fetchResult.enumerateObjects({asset, index, stop in
tempArr.append(asset)
})
// self.assets = tempArr
self.imageManager.startCachingImages(for: tempArr, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: nil)
tempArr.removeAll()
print("Asset count after initial fetch: \(self.assets?.count)")
DispatchQueue.main.async {
// Reload collection view once we've determined our Photos permissions.
print("inside of main queue reload")
PHPhotoLibrary.shared().register(self)
self.collectionView.delegate = self
self.collectionView.dataSource = self
self.collectionView.reloadData()
}
} else {
print("photo access denied")
self.displayPhotoAccessDeniedAlert()
}
}
在 cellForItemAt:
内部,我运行以下代码
cellForItemAt
guard let fetchResult = self.fetchResult else{
print("Fetch Result is empty")
return UICollectionViewCell()
}
let requestOptions = PHImageRequestOptions()
requestOptions.isSynchronous = false
requestOptions.deliveryMode = .highQualityFormat
//let scale = min(2.0, UIScreen.main.scale)
let scale = UIScreen.main.scale
let targetSize = CGSize(width: cell.bounds.width * scale, height: cell.bounds.height * scale)
// let asset = assets[indexPath.item]
let asset = fetchResult.object(at: indexPath.item)
let assetIdentifier = asset.localIdentifier
cell.representedAssetIdentifier = assetIdentifier
imageManager.requestImage(for: asset, targetSize: cell.frame.size,
contentMode: .aspectFill, options: requestOptions) { (image, hashable) in
if let loadedImage = image, let cellIdentifier = cell.representedAssetIdentifier {
// Verify that the cell still has the same asset identifier,
// so the image in a reused cell is not overwritten.
if cellIdentifier == assetIdentifier {
cell.imageView.image = loadedImage
}
}
}
最佳答案
本周我在使用 Apple 代码时遇到了类似的问题,其他人可以在此处获得引用 Browsing & Modifying Photos
内存使用率非常高,然后如果查看单个项目并返回根目录,内存会激增并且示例会崩溃。
因此,根据我们的实验,有一些改进性能的调整。
首先在为requestImage函数设置thumbnailSize时:
open func requestImage(for asset: PHAsset, targetSize: CGSize, contentMode: PHImageContentMode, options: PHImageRequestOptions?, resultHandler: @escaping (UIImage?, [AnyHashable : Any]?) -> Void) -> PHImageRequestID
我们像这样设置比例而不是使用完整尺寸:
UIScreen.main.scale * 0.75
我们还将 PHImageRequestOptions Resizing Mode
设置为 .fast
。
除此之外,我们发现设置 CollectionViewCell
的以下变量也有所帮助:
layer.shouldRasterize = true
layer.rasterizationScale = UIScreen.main.scale
isOpaque = true
我们还注意到 ScrollViewwDidScroll
方法中的 updateCachedAssets()
在此过程中发挥了一定作用,因此我们将其从回调中删除(正确或错误)。
最后一件事是我们为每个单元保留对 PHCachingImageManager
的引用,如果它存在,那么我们调用:
open func cancelImageRequest(_ requestID: PHImageRequestID)
因此,这是我们的 MediaCell
的代码:
extension MediaCell{
/// Populates The Cell From The PHAsset Data
///
/// - Parameter asset: PHAsset
func populateCellFrom(_ asset: PHAsset){
livePhotoBadgeImage = asset.mediaSubtypes.contains(.photoLive) ? PHLivePhotoView.livePhotoBadgeImage(options: .overContent) : nil
videoDuration = asset.mediaType == .video ? asset.duration.formattedString() : ""
representedAssetIdentifier = asset.localIdentifier
}
/// Shows The Activity Indicator When Downloading From The Cloud
func startAnimator(){
DispatchQueue.main.async {
self.activityIndicator.isHidden = false
self.activityIndicator.startAnimating()
}
}
/// Hides The Activity Indicator After The ICloud Asset Has Downloaded
func endAnimator(){
DispatchQueue.main.async {
self.activityIndicator.isHidden = true
self.activityIndicator.stopAnimating()
}
}
}
final class MediaCell: UICollectionViewCell, Animatable {
@IBOutlet private weak var imageView: UIImageView!
@IBOutlet private weak var livePhotoBadgeImageView: UIImageView!
@IBOutlet private weak var videoDurationLabel: UILabel!
@IBOutlet weak var activityIndicator: UIActivityIndicatorView!{
didSet{
activityIndicator.isHidden = true
}
}
var representedAssetIdentifier: String!
var requestIdentifier: PHImageRequestID!
var thumbnailImage: UIImage! {
didSet {
imageView.image = thumbnailImage
}
}
var livePhotoBadgeImage: UIImage! {
didSet {
livePhotoBadgeImageView.image = livePhotoBadgeImage
}
}
var videoDuration: String!{
didSet{
videoDurationLabel.text = videoDuration
}
}
//----------------
//MARK:- LifeCycle
//----------------
override func awakeFromNib() {
layer.shouldRasterize = true
layer.rasterizationScale = UIScreen.main.scale
isOpaque = true
}
override func prepareForReuse() {
super.prepareForReuse()
imageView.image = nil
representedAssetIdentifier = ""
requestIdentifier = nil
livePhotoBadgeImageView.image = nil
videoDuration = ""
activityIndicator.isHidden = true
activityIndicator.stopAnimating()
}
}
cellForItem
的代码:
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let asset = dataViewModel.assettAtIndexPath(indexPath)
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "mediaCell", for: indexPath) as! MediaCell
if let requestID = cell.requestIdentifier { imageManager.cancelImageRequest(requestID) }
cell.populateCellFrom(asset)
let options = PHImageRequestOptions()
options.resizeMode = .fast
options.isNetworkAccessAllowed = true
options.progressHandler = { (progress, error, stop, info) in
if progress == 0.0{
cell.startAnimator()
} else if progress == 1.0{
cell.endAnimator()
}
}
cell.requestIdentifier = imageManager.requestImage(for: asset, targetSize: thumbnailSize,
contentMode: .aspectFill, options: options,
resultHandler: { image, info in
if cell.representedAssetIdentifier == asset.localIdentifier {
cell.thumbnailImage = image
}
})
return cell
}
另一个区域在 updateCachedAssets() 函数中。您正在使用:
self.imageManager.startCachingImages(for: tempArr, targetSize: PHImageManagerMaximumSize, contentMode: .aspectFill, options: nil)
最好在此处设置较小的尺寸,例如:
imageManager.startCachingImages(for: addedAssets,
targetSize: thumbnailSize, contentMode: .aspectFill, options: nil)
因此缩略图大小例如:
/// Sets The Thumnail Image Size
private func setupThumbnailSize(){
let scale = isIpad ? UIScreen.main.scale : UIScreen.main.scale * 0.75
let cellSize = collectionViewFlowLayout.itemSize
thumbnailSize = CGSize(width: cellSize.width * scale, height: cellSize.height * scale)
}
所有这些调整都有助于确保内存使用量保持公平不变,并且在我们的测试中确保没有抛出异常。
希望对您有所帮助。
关于ios - 在 UICollectionView 中加载用户相册时内存增长失控,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58106814/