Swift：设置model后修改collectionViewCell中的UIStackView

Question

I have a UIStackView inside a collectionViewCell that I would like to modify depending on the Tweet object. If the Tweet object contains a retweet object, I would like to include the retweetedTextView to the stackView.

My current implementation doesn't render the stackView on screen at all. Code:

class TweetCell: UICollectionViewCell {
    
    //Initialize UI elements
    
    var tweet: Tweet? {
        didSet {
            if let tweet = tweet {
                
                if let _ = tweet.retweetedStatus {
                    bottomHStack = VStack(subviews: [
                        reactionHStack,
                        isRetweetedTextView,
                        tweetTextTextView,
                        timestampLabel
                    ], spacing: 8, layoutMargins: UIEdgeInsets(top: spacing, left: spacing, bottom: spacing, right: spacing))
                } else {
                    bottomHStack = VStack(subviews: [
                        reactionHStack,
                        tweetTextTextView,
                        timestampLabel
                    ], spacing: 8, layoutMargins: UIEdgeInsets(top: spacing, left: spacing, bottom: spacing, right: spacing))
                }   
            }
        }
    }
    
    var bottomHStack: VStack!
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        setupViews()
    }
    
    func setupViews() {

        //Other stackviews 
        
        bottomHStack = VStack(subviews: [
            reactionHStack,
            isRetweetedTextView,
            tweetTextTextView,
            timestampLabel
        ], spacing: 8, layoutMargins: UIEdgeInsets(top: spacing, left: spacing, bottom: spacing, right: spacing))
        
        //Overall stack
        let mainStack = VStack(subviews: [
            userHStack,
            mediaCollectionView,
            bottomHStack,
            separatorLine
        ])
        
        addSubview(mainStack)
        mainStack.topAnchor.constraint(equalTo: topAnchor).isActive = true
        mainStack.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
        mainStack.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
        mainStack.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
    } 

I have considered alternative ways to achieve the "removal of isRetweetedTextView ", but doesn't seem to be optimal, for example setting the heightConstraint to zero. Although it does appear to remove the isRetweetedTextView , the spacing in the stackView is still present.

I would like to completely remove the view from the stack.

Note that I am also implementing a similar feature to tweetTextTextView , ie if the tweetText is an empty string, I would like to remove it from the stackView as well. Creating different stackviews to cater for the varying combinations would be impractical.

Answer 1

There's a default behavior in UIStackView that it automatically removes a view and rearrange the stack if that view's isHidden property is true .

You could create one stack view with all possible views on it, then simply hide or show the views based on your needs. There is no need to initialize multiple stack views for the different possible arrangements of their underlying views.

For example, you could initialize one stack view with reactionHStack , isRetweetedTextView , tweetTextTextView , and timestampLabel , then make isRetweetedTextView.isHidden = true if there is no retweet.