无法使用 PhotoKit 获得从相册请求的清晰图像
Cannot get a clear image requested from Photo Album using PhotoKit
我正在使用 PhotoKit 来获取其中一个系统相册中的照片,如下所示:
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[fetchResult enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
NSLog(@"ALBUM NAME: %@", collection.localizedTitle);
if ([collection.localizedTitle isEqualToString:@"Camera Roll"]) {
PHFetchResult *photos = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
NSLog(@"PHOTOS: %ld", photos.count);
_photos = nil;
_photos = @[].mutableCopy;
for (PHAsset *asset in photos) {
[self loadImageFromPHAsset:asset];
}
}
}];
然后在我的自定义辅助方法中:(void)loadImageFromPHAsset:(PHAsset *)asset
,我有这个:
-(void)loadImageFromPHAsset:(PHAsset *)asset
{
PHImageManager *manager = [PHImageManager defaultManager];
CGSize targetSize = _layout.itemSize;
[manager requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage *result, NSDictionary *info) {
[_photos addObject:result];
}];
[self.collectionView reloadData];
}
所以我有一组图片,我将它们展示在我的 UICollectionViewCell
:
UIImage *image = [_photos objectAtIndex:indexPath.row];
cell.imageView.contentMode = UIViewContentModeScaleAspectFill;
cell.imageView.image = image;
但是我得到的是这样的,很模糊,怎么才能看清楚呢?
首先 targetSize 应该乘以比例来考虑屏幕的比例,这样,
CGFloat scale = [UIScreen mainScreen].scale;
CGSize targetSize = CGSizeMake(_layout.itemSize.width*scale, _layout.itemSize.height*scale);
其次,尝试这些选项以获得准确尺寸的图像,
//Async call returned on main thread, can return multiple times
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.resizeMode = PHImageRequestOptionsResizeModeExact;
最后,如果你有性能问题,使用PHCachingManager,我已经回答了关于性能改进的问题
希望对您有所帮助。
编辑:
我没有意识到图像存储在数组中。尝试在图像选项中设置同步标志。
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.synchronous = YES;
options.resizeMode = PHImageRequestOptionsResizeModeExact;
我正在使用 PhotoKit 来获取其中一个系统相册中的照片,如下所示:
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[fetchResult enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
NSLog(@"ALBUM NAME: %@", collection.localizedTitle);
if ([collection.localizedTitle isEqualToString:@"Camera Roll"]) {
PHFetchResult *photos = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
NSLog(@"PHOTOS: %ld", photos.count);
_photos = nil;
_photos = @[].mutableCopy;
for (PHAsset *asset in photos) {
[self loadImageFromPHAsset:asset];
}
}
}];
然后在我的自定义辅助方法中:(void)loadImageFromPHAsset:(PHAsset *)asset
,我有这个:
-(void)loadImageFromPHAsset:(PHAsset *)asset
{
PHImageManager *manager = [PHImageManager defaultManager];
CGSize targetSize = _layout.itemSize;
[manager requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage *result, NSDictionary *info) {
[_photos addObject:result];
}];
[self.collectionView reloadData];
}
所以我有一组图片,我将它们展示在我的 UICollectionViewCell
:
UIImage *image = [_photos objectAtIndex:indexPath.row];
cell.imageView.contentMode = UIViewContentModeScaleAspectFill;
cell.imageView.image = image;
但是我得到的是这样的,很模糊,怎么才能看清楚呢?
首先 targetSize 应该乘以比例来考虑屏幕的比例,这样,
CGFloat scale = [UIScreen mainScreen].scale;
CGSize targetSize = CGSizeMake(_layout.itemSize.width*scale, _layout.itemSize.height*scale);
其次,尝试这些选项以获得准确尺寸的图像,
//Async call returned on main thread, can return multiple times
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.resizeMode = PHImageRequestOptionsResizeModeExact;
最后,如果你有性能问题,使用PHCachingManager,我已经回答了关于性能改进的问题
希望对您有所帮助。
编辑:
我没有意识到图像存储在数组中。尝试在图像选项中设置同步标志。
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.synchronous = YES;
options.resizeMode = PHImageRequestOptionsResizeModeExact;