私はPhotos Frameworkを使用してUICollectionViewを生成しています。それは簡単なパターンでなければなりませんが、私は隠されたセルの要求を取り消すことに問題があります。iOS PHImageManager cancelImageRequestが機能しません。
これは、いくつかの例から取った、私のコードです:
まあ#pragma mark - UICollectionView DataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return [_photos count];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
GalleryViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
NSLog(@">>>>>>SHOWING CELL %d WITH MEMADDRESS %p", indexPath.row, cell);
PHAsset *asset = [_photos objectAtIndex:indexPath.row];
PHImageRequestOptions *option = [PHImageRequestOptions new];
option.synchronous = NO;
option.version = PHImageRequestOptionsVersionCurrent;
option.networkAccessAllowed = YES;
option.deliveryMode = PHImageRequestOptionsDeliveryModeOpportunistic;
option.resizeMode = PHImageRequestOptionsResizeModeFast;
PHImageRequestID requestId = cell.tag;
if(requestId != 0)
{
[_imgManager cancelImageRequest:requestId];
NSLog(@">>>>>>1ST CANCEL CELL %d WITH MEMADDRESS %p AND REQUESTID %d", indexPath.row, cell, requestId);
}
[cell.photoIV setImage:nil];
cell.tag = [_imgManager requestImageForAsset:asset
targetSize:CGSizeMake(CAMERA_GALLERY_SIZE, CAMERA_GALLERY_SIZE)
// contentMode:PHImageContentModeAspectFit
contentMode:PHImageContentModeDefault
options:option
resultHandler:^(UIImage *result, NSDictionary *info) {
//if([self isRowVisible:indexPath])
//{
[cell.photoIV setImage:result];
NSLog(@">>>>>>Assigning photo to cell %d with memaddress %p", indexPath.row, cell);
//}
//else
//{
// NSLog(@">>>>>>We should assign photo to cell %d with memaddress %p but this cell is not visible", indexPath.row, cell);
//}
}];
NSLog(@">>>>>>LOADING CELL %d WITH MEMADDRESS %p AND REQUESTID %d", indexPath.row, cell, requestId);
if([_selectedPhotos containsObject:asset])
[cell.selectedIV setHidden:NO];
else
[cell.selectedIV setHidden:YES];
[cell.isMineIV setHidden:YES];
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(@">>>>>>HIDDING CELL %d WITH MEMADDRESS %p", indexPath.row, cell);
[((GalleryViewCell *)cell).photoIV setImage:nil];
PHImageRequestID requestId = cell.tag;
if(requestId != 0)
{
[_imgManager cancelImageRequest:requestId];
NSLog(@">>>>>>2ND CANCEL CELL %d WITH MEMADDRESS %p AND REQUESTID %d", indexPath.row, cell, requestId);
}
}
-(BOOL) isRowVisible:(NSIndexPath *) indexPath
{
NSArray *indexes = [_photosCV indexPathsForVisibleItems];
for (NSIndexPath *index in indexes)
{
if (index.row == indexPath.row)
{
return YES;
}
}
return NO;
}
、私はコレクションビューにダウンとアップの高速スクロールを行う場合は、各セルが2枚のあるいは3の画像を示す、リフレッシュの数倍です1秒または2秒。 セルが表示されなくなったとき、またはセルが再び表示されているときに同じセルの前のリクエストをキャンセルしようとしていますが、結果を見て、ログを調べると、キャンセルされているリクエストはないようです。
スクロールダウンしてスクロールした後のログです。
2016-10-24 22:10:46.284 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 17 WITH MEMADDRESS 0x17351660
2016-10-24 22:10:46.286 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 17 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
2016-10-24 22:10:46.288 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 15 WITH MEMADDRESS 0x1736a890
2016-10-24 22:10:46.289 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 15 WITH MEMADDRESS 0x1736a890 AND REQUESTID 349
2016-10-24 22:10:46.291 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 0 WITH MEMADDRESS 0x1736a890
2016-10-24 22:10:46.291 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 0 WITH MEMADDRESS 0x1736a890 AND REQUESTID 349
2016-10-24 22:10:46.293 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 0 with memaddress 0x1736a890
2016-10-24 22:10:46.293 Fotoloop[9834:4281410] >>>>>>LOADING CELL 0 WITH MEMADDRESS 0x1736a890 AND REQUESTID 349
2016-10-24 22:10:46.298 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 1 WITH MEMADDRESS 0x17351660
2016-10-24 22:10:46.298 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 1 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
2016-10-24 22:10:46.301 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 1 with memaddress 0x17351660
2016-10-24 22:10:46.303 Fotoloop[9834:4281410] >>>>>>LOADING CELL 1 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
2016-10-24 22:10:46.310 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 2 WITH MEMADDRESS 0x1744d350
2016-10-24 22:10:46.311 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 2 WITH MEMADDRESS 0x1744d350 AND REQUESTID 350
2016-10-24 22:10:46.312 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 2 with memaddress 0x1744d350
2016-10-24 22:10:46.312 Fotoloop[9834:4281410] >>>>>>LOADING CELL 2 WITH MEMADDRESS 0x1744d350 AND REQUESTID 350
2016-10-24 22:10:46.316 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 3 WITH MEMADDRESS 0x171c0fd0
2016-10-24 22:10:46.317 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 3 WITH MEMADDRESS 0x171c0fd0 AND REQUESTID 348
2016-10-24 22:10:46.318 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 3 with memaddress 0x171c0fd0
2016-10-24 22:10:46.318 Fotoloop[9834:4281410] >>>>>>LOADING CELL 3 WITH MEMADDRESS 0x171c0fd0 AND REQUESTID 348
2016-10-24 22:10:46.325 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 4 WITH MEMADDRESS 0x15f15b60
2016-10-24 22:10:46.339 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 4 WITH MEMADDRESS 0x15f15b60 AND REQUESTID 347
2016-10-24 22:10:46.363 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 4 with memaddress 0x15f15b60
2016-10-24 22:10:46.365 Fotoloop[9834:4281410] >>>>>>LOADING CELL 4 WITH MEMADDRESS 0x15f15b60 AND REQUESTID 347
2016-10-24 22:10:46.371 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 5 WITH MEMADDRESS 0x1710b1b0
2016-10-24 22:10:46.373 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 5 WITH MEMADDRESS 0x1710b1b0 AND REQUESTID 346
2016-10-24 22:10:46.376 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 5 with memaddress 0x1710b1b0
2016-10-24 22:10:46.377 Fotoloop[9834:4281410] >>>>>>LOADING CELL 5 WITH MEMADDRESS 0x1710b1b0 AND REQUESTID 346
2016-10-24 22:10:46.399 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 23 with memaddress 0x171d3600
2016-10-24 22:10:46.401 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 16 with memaddress 0x1744d350
2016-10-24 22:10:46.408 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 12 WITH MEMADDRESS 0x15feda90
2016-10-24 22:10:46.408 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 12 WITH MEMADDRESS 0x15feda90 AND REQUESTID 352
2016-10-24 22:10:46.409 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 13 WITH MEMADDRESS 0x171d7d00
2016-10-24 22:10:46.409 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 13 WITH MEMADDRESS 0x171d7d00 AND REQUESTID 353
2016-10-24 22:10:46.410 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 14 WITH MEMADDRESS 0x171ef8d0
2016-10-24 22:10:46.410 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 14 WITH MEMADDRESS 0x171ef8d0 AND REQUESTID 354
2016-10-24 22:10:46.430 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 19 with memaddress 0x15f15b60
2016-10-24 22:10:46.490 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 15 with memaddress 0x1736a890
2016-10-24 22:10:46.504 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 0 with memaddress 0x1736a890
2016-10-24 22:10:46.551 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 17 with memaddress 0x17351660
2016-10-24 22:10:46.614 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 13 with memaddress 0x171d7d00
2016-10-24 22:10:46.677 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 9 with memaddress 0x1735b730
2016-10-24 22:10:46.743 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 12 with memaddress 0x15feda90
2016-10-24 22:10:46.808 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 10 with memaddress 0x171e3660
2016-10-24 22:10:46.865 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 14 with memaddress 0x171ef8d0
2016-10-24 22:10:46.927 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 11 with memaddress 0x15f27020
2016-10-24 22:10:46.996 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 6 with memaddress 0x171d3600
2016-10-24 22:10:47.053 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 7 with memaddress 0x17133010
2016-10-24 22:10:47.088 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 3 with memaddress 0x171c0fd0
2016-10-24 22:10:47.114 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 4 with memaddress 0x15f15b60
2016-10-24 22:10:47.118 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 2 with memaddress 0x1744d350
2016-10-24 22:10:47.122 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 1 with memaddress 0x17351660
2016-10-24 22:10:47.125 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 8 with memaddress 0x15f06e30
2016-10-24 22:10:47.213 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 5 with memaddress 0x1710b1b0
ご覧のとおり、セル17(0x17351660)は非表示になっており、そのリクエストはキャンセルされます。
2016-10-24 22:10:46.284 Fotoloop[9834:4281410] >>>>>>HIDDING CELL 17 WITH MEMADDRESS 0x17351660
2016-10-24 22:10:46.286 Fotoloop[9834:4281410] >>>>>>2ND CANCEL CELL 17 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
ちょうどその後、セル1(0x17351660)が示されていると私は、このセルのための新しい要求を初期化。
2016-10-24 22:10:46.298 Fotoloop[9834:4281410] >>>>>>SHOWING CELL 1 WITH MEMADDRESS 0x17351660
2016-10-24 22:10:46.298 Fotoloop[9834:4281410] >>>>>>1ST CANCEL CELL 1 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
2016-10-24 22:10:46.301 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 1 with memaddress 0x17351660
2016-10-24 22:10:46.303 Fotoloop[9834:4281410] >>>>>>LOADING CELL 1 WITH MEMADDRESS 0x17351660 AND REQUESTID 351
しかし、いくつかの時間後に私はこれがあります。
2016-10-24 22:10:46.551 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 17 with memaddress 0x17351660
2016-10-24 22:10:47.122 Fotoloop[9834:4281410] >>>>>>Assigning photo to cell 1 with memaddress 0x17351660
をそして、私は第二に、そのセルに示した2枚の画像を見ることができます。 isRowVisibleブロックのコメントを外すとこの醜い効果は見られませんが、コードの要求をキャンセルすると問題が発生し、多数の写真でパフォーマンスが低下することがあります。 私はここで何が欠けていますか?
誰かが私と同じ問題を抱えている場合に備えて、コメントを追加したいと思います。 iOS 10で作業している場合、メソッドisRowVisibleはfalseを非常に頻繁に返します.iOS 10では、セルが表示される前にデフォルトでcellForItemAtIndexPathが呼び出されるためです。これを避けるために[mycollectionview setPrefetchingEnabled:NO]を入れなければなりませんでした。 – Wonton