Question

我正在使用UICollectionView，我有一个主类，另一个是UICollectionViewFlowLayout的子类。事情就是主要类中单元格的宽度和高度为0.在子类中，单元格的大小合适。

这是一些代码： FlowLayoutSubClass

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewLayoutAttributes* currentItemAttributes = [super layoutAttributesForItemAtIndexPath:indexPath];

if (!currentItemAttributes) {
    currentItemAttributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
}

CGFloat containerWidth = self.collectionView.frame.size.width;
CGFloat cellWidth = containerWidth / 2.0f - 1.0f;
CGFloat baseHeight = containerWidth / 4.0f;


CGRect frame = [self frameForIndexPath:indexPath];
if (CGRectEqualToRect(frame, CGRectZero)) {
    ArtworkModel *currentObject = [self.artworksArray objectAtIndex:indexPath.row];
    CGFloat height = currentObject.height;
    frame.origin = [self getNextFreePosition];
    frame.size.width = cellWidth;
    frame.size.height = 120 + arc4random() % (200 - 120);
    [self saveFrame:frame forIndexPath:indexPath];
    [self saveFrame:frame];
}

currentItemAttributes.frame = frame;
currentItemAttributes.size = frame.size;


return currentItemAttributes;
}
- (CGRect)frameForIndexPath:(NSIndexPath *)indexPath {
CGRect frame = CGRectZero;
NSString *key = [NSString stringWithFormat:@"%ld-%ld", (long)indexPath.section, (long)indexPath.row];
NSString *frameString = [self.framesByIndexPath objectForKey:key];
if (frameString) {
    frame = CGRectFromString(frameString);
}
return frame;
}

- (void)saveFrame:(CGRect)frame forIndexPath:(NSIndexPath *)indexPath {
if (!self.framesByIndexPath) {
    self.framesByIndexPath = [[NSMutableDictionary alloc] init];
}
NSString *key = [NSString stringWithFormat:@"%d-%d", indexPath.section, indexPath.row];
[self.framesByIndexPath setObject:NSStringFromCGRect(frame) forKey:key];
}

- (CGPoint)getNextFreePosition {
CGFloat containerWidth = self.collectionView.frame.size.width;
CGFloat cellWidth = containerWidth / 2.0f;

CGPoint point = CGPointZero;

NSArray *leftFrames = [self.framesDictionary valueForKey:@"left"];
NSArray *rightFrames = [self.framesDictionary valueForKey:@"right"];

NSString *lastLeftFrameString = [leftFrames lastObject];
NSString *lastRightFrameString = [rightFrames lastObject];
if (lastLeftFrameString == nil) {
    // There is no frame saved yet, so this will be the first
    point.x = 0.0f;
    point.y = 0.0f;
} else {
    if (lastRightFrameString == nil) {
        // There is no item on the right side
        point.x = cellWidth;
        point.y = 0.0f;
    } else {
        // There are items on both left and right sides...
        // Check which one has the smallest Y component
        CGRect leftFrame = CGRectFromString(lastLeftFrameString);
        CGRect rightFrame = CGRectFromString(lastRightFrameString);
        if (CGRectGetMaxY(leftFrame) <= CGRectGetMaxY(rightFrame)) {
            // We put this one on the left
            point.x = 0.0f;
            point.y = CGRectGetMaxY(leftFrame);
        } else {
            point.x = cellWidth;
            point.y = CGRectGetMaxY(rightFrame);
        }
    }
}
return point;
}

- (void)saveFrame:(CGRect)frame {
if (!self.framesDictionary) {
    self.framesDictionary = [[NSMutableDictionary alloc] init];
}
NSString *sideKey = nil;
if (CGRectGetMinX(frame) == 0.0f) {
    // left
    sideKey = @"left";
} else {
    sideKey = @"right";
}
NSMutableArray *frames = [self.framesDictionary objectForKey:sideKey];
if (!frames) {
    frames = [[NSMutableArray alloc] init];
    [self.framesDictionary setObject:frames forKey:sideKey];
}
[frames addObject:NSStringFromCGRect(frame)];
}
@end

和主要课程：

- (void)takeAllArtworks {
[WaitingView showWaitingView:shadowView WithIndicator:indicatorActivity];
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSMutableString *requestURL = [[NSMutableString alloc] init];
[requestURL appendFormat:@"%@%@", BASE_URL_ARTWORK, GET_ARTWORKS];

//    NSInteger screenWidth = self.view.frame.size.width / 2.0f;
[manager GET:requestURL parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
    if ([[responseObject objectForKey: @"status"] integerValue] == 0) {
        NSArray *artworks = [responseObject objectForKey:@"Data"];
        if ([artworks count] > 0) {
            for (NSDictionary *dict in artworks) {
                ArtworkModel *artwork = [[ArtworkModel alloc] init];
                if ([dict objectForKey:@"Title"] != [NSNull null]) {
                    artwork.title = [dict objectForKey:@"Title"];
                }
                if ([dict objectForKey:@"Description"] != [NSNull null]) {
                    artwork.descriptionAlbum = [dict objectForKey:@"Description"];
                }
                if ([dict objectForKey:@"ArtistName"] != [NSNull null]) {
                    artwork.artistName = [dict objectForKey:@"ArtistName"];
                }

                NSString *dateAdded = [[dict objectForKey:@"DateAdded"] substringWithRange:NSMakeRange(0, 19)];
                NSString *dateUpdated = [[dict objectForKey:@"DateUpdated"] substringWithRange:NSMakeRange(0, 19)];

                NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
                [formatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];
                NSDate *dateAd = [formatter dateFromString:dateAdded];
                NSDate *dateUp = [formatter dateFromString:dateUpdated];

                NSString *result;

                if ([dateAd compare:dateUp] == NSOrderedAscending) {
                    result = [NSString stringWithFormat:@"edited %@", [self relativeDateStringForDate:dateUp]];
                } else {
                    result = [self relativeDateStringForDate:dateAd];
                }

                artwork.dateAdded = result;

                if ([dict objectForKey:@"MediaItems"] != [NSNull null]) {
                    NSArray *mediaArray = [dict objectForKey:@"MediaItems"];

                    if ([mediaArray count] > 0) {
                        for (NSDictionary *mediaDict in mediaArray) {
//                                NSString *endpoint = [NSString stringWithFormat:@"%@.ashx?w=%ld&h=%d&mode=crop", [mediaDict objectForKey:@"Url"], (long)screenWidth, 170];
                            NSString *endpoint = [mediaDict objectForKey:@"Url"];
                            NSString *imageURL = [NSString stringWithFormat:@"%@%@", IMAGE_BASE_URL, endpoint];
                            NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageURL]];
                            [artwork.imageUrls addObject:[UIImage imageWithData:data]];

                        }
                    }
                }

                [listOfArtworks addObject:artwork];
            }

            FBFlowLayout *layout = [[FBFlowLayout alloc] initWithArtworks:listOfArtworks];
            [layout setMinimumInteritemSpacing:0.5f];
            [layout setMinimumLineSpacing:0.5f];
            layout.scrollDirection = UICollectionViewScrollDirectionVertical;

           [artworkCollectionView reloadData];

            artworkCollectionView.collectionViewLayout = layout;

            [WaitingView hideWaitingView:shadowView WithIndicator:indicatorActivity];
        } else {
            [WaitingView hideWaitingView:shadowView WithIndicator:indicatorActivity];
        }
    }
    else
        [WaitingView hideWaitingView:shadowView WithIndicator:indicatorActivity];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Faild");
     [WaitingView hideWaitingView:shadowView WithIndicator:indicatorActivity];
}];

}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [listOfArtworks count];
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
FBWorkartCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"WorkartCollection" forIndexPath: indexPath];

ArtworkModel *artworkModel = (ArtworkModel *)[listOfArtworks objectAtIndex:indexPath.row];
cell.nameAlbumLabel.text = artworkModel.title;
cell.nameArtistLabel.text = artworkModel.artistName;

if ([artworkModel.imageUrls count] > 0) {
    cell.coverAlbumPhoto.image = [artworkModel.imageUrls objectAtIndex:0];
}

cell.shadowView.alpha = 0.9;
cell.dateLabel.text = artworkModel.dateAdded;

CGFloat hue = ( arc4random() % 256 / 256.0 );  //  0.0 to 1.0
CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from white
CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from black
UIColor *color = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];

cell.backgroundColor = color;
return cell;
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
ArtworkModel *artworkModel = (ArtworkModel *)[listOfArtworks objectAtIndex:indexPath.row];

FBWorkDetailsViewController *dvc = [[FBWorkDetailsViewController alloc] initWithArtwork:artworkModel];
FBLeftMenuViewController *left = [[FBLeftMenuViewController alloc] init];
MFSideMenuContainerViewController *container = [MFSideMenuContainerViewController
                                                containerWithCenterViewController: dvc
                                                leftMenuViewController: left
                                                rightMenuViewController:nil
                                                withHeader: YES];
[container.titleLabel setText:@"WORK DETAILS"];
[self.navigationController pushViewController: container animated: YES];
}


- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

return [collectionViewLayout layoutAttributesForItemAtIndexPath:indexPath].size;
}

Answer 1

首先，如果你有一个UIcollectionViewLayout的子类，为什么不在故事板中设置

第二，你的

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

return [collectionViewLayout layoutAttributesForItemAtIndexPath:indexPath].size;
}

是多余的，您是否尝试在NSLog上return之前[collectionViewLayout layoutAttributesForItemAtIndexPath:indexPath].size;返回有效大小？

UICollectionViewCell宽度和高度0

1 个答案: