ios - 如何设置动态 UICollectionView 单元格高度？

Question

如何设置动态单元格高度？

我需要在这个方法中设置单元格大小:

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell 

我试着这样做:

cell.bounds = CGRect(x: cell.bounds.origin.x, y: cell.bounds.origin.y, width: width, height: height) 

但是我不能向下滚动...

我试试这个方法:

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize 

但是这个方法是先调用，然后再调用这个方法:

cell.bounds = CGRect(x: cell.bounds.origin.x, y: cell.bounds.origin.y, width: width, height: height) 

那么..如何改变单元格高度？

Answer 1

首先，按照正常设置。 (正常约束 [左、右、顶部、底部和高度] 和 UICollectionView 的 IBOutlet。

其次，为高度约束、顶部约束和底部约束制作IBOutlets。

第三，添加->

//these are the outlets I am naming generic names but name them what you wish

 IBOutlet var collectionViewCellDynamicConstraint: NSLayoutConstraint!
 IBOutlet var topConstraintDynamicConstraint: NSLayoutConstraint!
 IBOutlet var bottomConstraintDynamicConstraint: NSLayoutConstraint!

 //into viewDidLoad

 collectionViewCell.addObserver(self, forKeyPath: "contentHeight",      options:NSKeyValueObservingOptions.New, context: nil)

  topConstraintDynamicConstraint.addObserver(self, forKeyPath: "contentTop", options:NSKeyValueObservingOptions.New, context: nil)

  bottomConstraintDynamicConstraint.addObserver(self, forKeyPath: "contentBottom", options:NSKeyValueObservingOptions.New, context: nil)

 //create this override func

 override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {



 //try use this segment below as well but if it doesn't work then remove it and try run again

 self.collectionViewCell.sizeThatFits()

 //



 self.collectionViewCellDynamicConstraint.constant = collectionViewCell.sizeThatFits(CGSizeMake(self.collectionViewCell.frame.size.width, CGFloat.max)).height

 // set these values (below) to the space/value that you set them at normally. Often what is needed is a refresh after changing the height of the view/collectionViewCell

    self.topSpaceOld.constant = 0.4 

    self.bottomSpaceOld.constant = 10


}




 // you need to de-initialise them before you leave the view or else it will crash
deinit {
    self.collectionViewCell.removeObserver(self, forKeyPath: "contentHeight")

    self.topConstraintDynamicConstraint.removeObserver(self, forKeyPath: "contentTop"

    self.bottomConstraintDynamicConstraint.removeObserver(self, forKeyPath: "contentBottom")
 )



}

可能存在一些命名问题，但应该可以。此代码用于让 UITextView 在 ScrollView 内部工作以获得 View 的动态高度。应该是同一个概念。