Question

这是我以前第一次尝试制作UICollectionView，我有一个正在从coreData读取的ImageArray ..所有的图像都是NSData我正在将它们读成UIImage ...我会喜欢的将UIImage显示到UICollectionView中，我允许用户选择更新预览视图。

我已将这3名代表添加到我的班级。

这些是我实施的代表。

// add collectionView
photoCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(10.0, 50.0, 200.0, 700.0)];
    [photoCollectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"PhotoCell"];
    photoCollectionView.dataSource = self;
    photoCollectionView.delegate = self;
    [self.view addSubview:photoCollectionView];


//..

#pragma mark - CollectionView Delegates
#pragma mark -- UICollectionView Datasource
- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section {
    return [imageArray count];
}

- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView {
    return 1;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [cv dequeueReusableCellWithReuseIdentifier:@"PhotoCell" forIndexPath:indexPath];
    cell.backgroundColor = [UIColor whiteColor];
    return cell;
}


#pragma mark -- UICollectionView Delegate
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    // TODO: Select Item
}
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
    // TODO: Deselect item
}


#pragma mark –- UICollectionViewDelegate FlowLayout


- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    NSDictionary *currentPhotoDict = [imageArray objectAtIndex:indexPath.row];
    UIImage *imageForCollection = [UIImage imageWithData:[currentPhotoDict objectForKey:@"DImage"]];

    //show image in collectionview?

}


- (UIEdgeInsets)collectionView:
(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
    return UIEdgeInsetsMake(50, 20, 50, 20);

}

当我运行上面的代码时，我收到以下错误。

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'UICollectionView must be initialized with a non-nil layout parameter'

Answer 1

该错误表明您需要使用非零布局对象创建集合视图。

你需要使用......

photoCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(10.0, 50.0, 200.0, 700.0) collectionViewLayout:someLayoutObject];

您首先需要创建布局对象。

可能只是使用......

photoCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(10.0, 50.0, 200.0, 700.0) collectionViewLayout:[[UICollectionViewFlowLayout alloc] init]];

Answer 2

初始化集合视图时，您需要指定要使用的布局类型：

UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc] init];
photoCollectionView =[[UICollectionView alloc] initWithFrame:CGRectMake(10.0, 50.0, 200.0, 700.0) collectionViewLayout:layout];

自定义UICollectionView的UIImages错误

2 个答案: