子類UICollectionViewCell沒有更新的圖像

Question

我試圖通過在每個單元視圖中添加一個徽章，使集合視圖顯示多個選擇。它正確設置了初始（未選定）圖像，但視圖從未更新爲選定版本。我試着手動設置它，所以我知道所選圖像的作品，並在單元格中可見。 NSLog顯示'selected'正在按預期切換，斷點顯示正在執行對圖像的適當分配。不好意思，SO不會打得很好，而且在午夜之後。

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
{ 
    SMListCollectionViewCell *cell = (SMListCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath]; 

if (!indexPath.row) 
{ 
    cell.image.image = [UIImage imageNamed:@"Add"]; 
    cell.label.text = @"Create New"; 
    cell.imageBadge.hidden = YES; 
} 
else 
{ 
    cell.image.image = [UIImage imageNamed:[listManager.myLists[indexPath.row-1] valueForKey:keyDetailImage]]; 
    cell.label.text = [listManager.myLists[indexPath.row-1] valueForKey:keyName]; 
    cell.imageBadge.hidden = !self.editing; 
    NSLog(@"selected is %d",cell.selected); 
    if (cell.selected) 
    { 
     cell.imageBadge.image = self.badgeSelected; 
    } 
    else 
    { 
     cell.imageBadge.image = self.badgeUnselected; 
    } 
} 
return cell; 
} 

Answer 1

哇！從內部cellForAtIndexPath:是保證不工作檢查一個cell的selected狀態。

由於您已經創建了自定義單元格子類SMListCollectionViewCell，您需要覆蓋其selected設置器&切換要顯示在單元格中的圖像。

由於imageBadge屬性在SMListCollectionViewCell.h已經暴露出來，只有.m快速片段看起來像：

// SMListCollectionViewCell.m 

#import "SMListCollectionViewCell.h" 

@implementation SMListCollectionViewCell 

... 

- (void)setSelected:(BOOL)selected{ 
    [super setSelected:selected]; 

    if (selected){ 
     cell.imageBadge.image = self.badgeSelected; 
    } 
    else { 
     cell.imageBadge.image = self.badgeUnselected; 
    } 
} 

@end 

這將處理取決於細胞選擇狀態圖像的切換。

此外，cellForItemAtIndexPath:現在就變身到：

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
{ 
    SMListCollectionViewCell *cell = (SMListCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath]; 

    if (!indexPath.row){ 

     cell.image.image = [UIImage imageNamed:@"Add"]; 
     cell.label.text = @"Create New"; 
     cell.imageBadge.hidden = YES; 
    } 
    else { 

     cell.image.image = [UIImage imageNamed:[listManager.myLists[indexPath.row-1] valueForKey:keyDetailImage]]; 
     cell.label.text = [listManager.myLists[indexPath.row-1] valueForKey:keyName]; 
     cell.imageBadge.hidden = !self.editing; 
    } 

    return cell; 
}