设置一些气泡的最小宽度

Question

我想知道为某些气泡设置最小宽度的正确方法是什么。我已经尝试覆盖 applyLayoutAttributes: 在我的自定义单元格中，但我需要访问我的数据源才能知道哪个单元格应该具有最小宽度。我一直在修改 cellForItemAtIndexPath: 中的 messageBubbleLeftRightMargin: 但没有结果。任何指针都会很棒

编辑

我的 Message 模型（符合）有一个标志告诉我气泡是否需要有最小宽度

在我的自定义单元格中，我可以覆盖自定义布局，但我无权访问数据源，因此我无权访问该标志

-(void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes{
            JSQMessagesCollectionViewLayoutAttributes *customAttributes = (JSQMessagesCollectionViewLayoutAttributes *)layoutAttributes;

    // I need access to my <JSQMessageData> for the condition
            if (condition) {
                if(customAttributes.messageBubbleContainerViewWidth <175){
                    customAttributes.messageBubbleContainerViewWidth = 175;
                }
            }

            [super applyLayoutAttributes:customAttributes];
}

我也尝试在我的 JSQMessagesViewController 子类中访问左右约束，但无济于事

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    /**
     *  Override point for customizing cells
     */
    JSQMessagesCollectionViewCell *cell = (JSQMessagesCollectionViewCell *)[super collectionView:collectionView cellForItemAtIndexPath:indexPath];

    BLMessage *message = [self.visibleMessagesArray objectAtIndex:indexPath.item];

    JSQMessagesCollectionViewLayoutAttributes *customAttributes = [JSQMessagesCollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];

    if(message.isEphemeral){
      //random number to see if it had an effect
      self.collectionView.collectionViewLayout.messageBubbleLeftRightMargin = 200;

       //I also tried modifying the customAttributes
       //customAttributes.messageBubbleContainerViewWidth = 175;

    }
    return cell;
}

我是 UICollectionViewFlowLayout 等方面的新手，我可能会遗漏一些核心概念

Answer 1

好的，所以我发现出了什么问题。我没有将新布局应用于单元格，所以我的 cellForItemAtIndexPath 最终变成了这样：

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    /**
     *  Override point for customizing cells
     */
    JSQMessagesCollectionViewCell *cell = (JSQMessagesCollectionViewCell *)[super collectionView:collectionView cellForItemAtIndexPath:indexPath];

    BLMessage *message = [self.visibleMessagesArray objectAtIndex:indexPath.item];

    JSQMessagesCollectionViewLayoutAttributes *customAttributes = (JSQMessagesCollectionViewLayoutAttributes *)[self.collectionView layoutAttributesForItemAtIndexPath:indexPath];

    if(message.isEphemeral){
       //I also tried modifying the customAttributes
       customAttributes.messageBubbleContainerViewWidth = 175;
       [cell applyLayoutAttributes: customAttributes];

    }
    return cell;
}

------------编辑------------

我之前的回答有一些副作用，不建议在你的collectionView:cellForItemAtIndexPath:中调用applyLayoutAttributes:。

正确的做法是继承 JSQMessagesCollectionViewFlowLayout

CustomCollectionViewFlowLayout.h

#import "JSQMessagesCollectionViewFlowLayout.h"

@interface CustomCollectionViewFlowLayout : JSQMessagesCollectionViewFlowLayout
@property (strong, nonatomic) UIImageView *incomingBubbleMask;
@end

CustomCollectionViewFlowLayout.m

#import "CustomCollectionViewFlowLayout.h"
#import "JSQMessage.h"

#import "JSQMessagesCollectionView.h"
#import "JSQMessagesCollectionViewCell.h"

#import "JSQMessagesCollectionViewLayoutAttributes.h"
#import "JSQMessagesCollectionViewFlowLayoutInvalidationContext.h"

#import "UIImage+JSQMessages.h"

@implementation CustomCollectionViewFlowLayout
+ (Class)layoutAttributesClass
{
    return [JSQMessagesCollectionViewLayoutAttributes class];
}

- (CGSize)messageBubbleSizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CGSize superSize = [super messageBubbleSizeForItemAtIndexPath:indexPath];

    JSQMessage *currentMessage = (JSQMessage *)[self.collectionView.dataSource collectionView:self.collectionView messageDataForItemAtIndexPath:indexPath];

    /*********** Setting size **************/
    //check if outgoing, you can import your Session Manager to check your user identifier
    if ([currentMessage.senderId isEqualToString:@"me") {
        superSize = CGSizeMake(175, superSize.height);
    }
    //do whatever other checks and setup your width/height accordingly

    return superSize;
}

@end

不要忘记在 JSQMessagesViewController 子类中设置自定义布局，#import "CustomCollectionViewFlowLayout.h" 并在 viewDidLoad 中添加：self.collectionView.collectionViewLayout = [[CustomCollectionViewFlowLayout alloc] init];

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