ios CollectionView sizeForItemAtIndexPath 从未调用过
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CollectionView sizeForItemAtIndexPath never called
提问by john doe
This is driving me crazy! I have a UICollectionViewController as shown below:
这真让我抓狂！我有一个 UICollectionViewController 如下所示：
class PhrasesCompactCollectionViewController: UICollectionViewController
The numberOfSections and cellForItemAt are being called but the sizeForItemAtIndexPath is never called. I am using the same exact code somewhere else and it fires correctly. I am using Xcode 8 Beta 6.
正在调用 numberOfSections 和 cellForItemAt，但从未调用过 sizeForItemAtIndexPath。我在其他地方使用完全相同的代码并且它正确触发。我正在使用 Xcode 8 Beta 6。
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSize(width: 120, height:120)
}
回答by almas
You need to specify that you implement the protocol UICollectionViewDelegateFlowLayoutin your class declaration.
您需要UICollectionViewDelegateFlowLayout在类声明中指定实现协议。
class PhrasesCompactCollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout
class PhrasesCompactCollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout
回答by Shiv Kumar
In Swift 3+Use this method:
在Swift 3+ 中使用此方法：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width:(collectionView.frame.height-90)/2, height: 100)
}
Make sure that your class complies both Delegate
确保您的班级符合委托
UICollectionViewDelegate
UICollectionViewDelegateFlowLayout
UICollectionViewDelegate
UICollectionViewDelegateFlowLayout
回答by Zenman C
I had the same problem. The one thing that helped me was to make the 'Estimated Size' for the Cell Size under the collectionView size inspector 'None'.
我有同样的问题。帮助我的一件事是在 collectionView 大小检查器“无”下为单元格大小设置“估计大小”。
回答by Gaurav Rami
Swift 3
斯威夫特 3
To set Cell Size of UICollectionView, you need to create and customise object of UICollectionViewFlowLayout. Customise the properties and set that layout object to the UICollectionView object.
要设置 UICollectionView 的 Cell Size，您需要创建和自定义UICollectionViewFlowLayout. 自定义属性并将该布局对象设置为 UICollectionView 对象。
Change cellheight and cell cellWidth objects according to your requirement (the cell hight and width you want).
根据您的要求（您想要的单元格高度和宽度）更改 cellheight 和 cell cellWidth 对象。
override func viewDidLoad() {
super.viewDidLoad()
let cellWidth : CGFloat = myCollectionView.frame.size.width / 4.0
let cellheight : CGFloat = myCollectionView.frame.size.height - 2.0
let cellSize = CGSize(width: cellWidth , height:cellheight)
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical //.horizontal
layout.itemSize = cellSize
layout.sectionInset = UIEdgeInsets(top: 1, left: 1, bottom: 1, right: 1)
layout.minimumLineSpacing = 1.0
layout.minimumInteritemSpacing = 1.0
myCollectionView.setCollectionViewLayout(layout, animated: true)
myCollectionView.reloadData()
}
Make Sure: if you added sizeForItemAt indexPath method then must REMOVE the method...
确保：如果您添加了 sizeForItemAt indexPath 方法，则必须删除该方法...
Remove Below Method
删除下面的方法
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
}
回答by Xys
Swift 5
斯威夫特 5
All these steps are required:
所有这些步骤都是必需的：
- Conform to UICollectionViewDelegateFlowLayout<== Absolutely needed !!
- and to
UICollectionViewDelegate, UICollectionViewDataSource - Set these in viewDidLoad :
collectionView.delegate = selfandcollectionView.dataSource = self - Set Estimate Size to Nonein the Interface Builder
- Make sure the following method has sizeForItemAtand not sizeForItemAtIndexPath
- 符合UICollectionViewDelegateFlowLayout<== 绝对需要！！
- 并
UICollectionViewDelegate, UICollectionViewDataSource - 在 viewDidLoad 中设置这些：
collectionView.delegate = self和collectionView.dataSource = self - 在 Interface Builder 中将Estimate Size设置为 None
- 确保以下方法具有sizeForItemAt而不是sizeForItemAtIndexPath
as :
作为 ：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
{
return CGSize(width: 100, height:100)
}
回答by H S Progr
First class need confirm to UICollectionViewDelegateFlowLayout. Then you need to write following code in viewDidLoad():
第一类需要确认 UICollectionViewDelegateFlowLayout。然后你需要在 viewDidLoad() 中编写以下代码：
//To tell the UICollectionView to use your UIViewController's UICollectionViewDelegateFlowLayout methods
//告诉 UICollectionView 使用你的 UIViewController 的 UICollectionViewDelegateFlowLayout 方法
collectionView.delegate = self
// If you want to set your own collection view flow layout
// 如果要设置自己的集合视图流布局
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical //depending upon direction of collection view
self.collectionView?.setCollectionViewLayout(layout, animated: true)
By using this code UICollectionViewDelegateFlowLayout method
通过使用此代码 UICollectionViewDelegateFlowLayout 方法
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
will get called, you can set size in this method.
将被调用，您可以在此方法中设置大小。
回答by Manish
Three things you need to check if no answer works:
如果没有答案，您需要检查三件事：
Implement FlowLayout Delegate :
class MyController: UICollectionViewController, UICollectionViewDelegateFlowLayoutUse method for size of item for swift 3.0+:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize(width: (collectionView.frame.width / 3) - 1, height: collectionView.frame.width) }Select
Estimate size = Nonein Inspect element of UICollectionView.
实现 FlowLayout 委托：
class MyController: UICollectionViewController, UICollectionViewDelegateFlowLayoutswift 3.0+ 项目大小的使用方法：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize(width: (collectionView.frame.width / 3) - 1, height: collectionView.frame.width) }选择
Estimate size = None在检查UICollectionView的元素。
回答by Stephen Rains
I had the same problem and nothing would fix it. I had a yellow warning saying to make it private because it came close to another function defined by the Layout Delegate. What fixed it for me was:
我有同样的问题，没有什么可以解决它。我有一个黄色警告说将其设为私有，因为它与布局委托定义的另一个函数很接近。为我修复的是：
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
Notice the difference from "sizeForItemAtIndexPath" to the correct "sizeForItemAt".
注意从“sizeForItemAtIndexPath”到正确的“sizeForItemAt”的区别。
I tore my hair out for days trying to figure this out and it finally worked. Below I will include all of my function to show you how I also "hid" a cell by making the height equal to 0.
我把头发扯了好几天试图解决这个问题，它终于奏效了。下面我将包括我的所有函数，向您展示我如何通过使高度等于 0 来“隐藏”一个单元格。
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let findIndex = labelArray.index(of: "\(labelArray[indexPath.row])")
let screenSize = UIScreen.main.bounds
let screenWidth = screenSize.width
if (findIndex! % 2 == 0){
// Even index, show cell
return CGSize(width: screenWidth, height: 246)
}
else {
return CGSize(width: screenWidth, height: 0)
}
}
回答by Charlie Seligman
I had this issue last night. Finally solved it at midnight when I realised 'didSelectItemAtIndex' method was not closed off with a closure bracket "}"
我昨晚遇到了这个问题。当我意识到 'didSelectItemAtIndex' 方法没有用闭包括号“}”关闭时，终于在午夜解决了它
I added a closure bracket at the very bottom of the class when asked by the compile error. So in effect all the methods below 'didSelectItemAtIndex' were inside that method.
当编译错误询问时，我在类的最底部添加了一个闭包括号。因此，实际上“didSelectItemAtIndex”下面的所有方法都在该方法中。
Posting here just in case anyone else wastes 4 hours of their evenings on this one :-(
在这里发帖以防万一其他人在这个晚上浪费了 4 个小时:-(
回答by Azam
Make sure you put this in viewDidLoad()
确保你把它放在 viewDidLoad()
collectionView.delegate = self
