iOS UICollectionView estimatedItemSize 自定適應高度（一）

摘要： iOS UICollectionView 計算高度(二) UICollectionViewFlowLayout 中有屬性estimatedItemSize（UITableView也有這個屬性，操作比UICollectionView簡單） 預設是0，只要設定不是0 就會呼叫UIColle...

iOS UICollectionView 計算高度(二)

UICollectionViewFlowLayout 中有屬性estimatedItemSize（UITableView也有這個屬性，操作比UICollectionView簡單） 預設是0，只要設定不是0 就會呼叫UICollectionViewCell當中的preferredLayoutAttributesFitting方法。

xib約束 多個label自適應（一個label只需要上下左右約束即可）

xib搭建UICollectionViewCell 有兩種方法可以自適應高度

1、使用SnapKit 給contentView約束 （使用系統約束沒寫出來）（感謝向陽我大哥）（如果只在xib中處理不需要在cell中操作 請大神指教）

//self.contentView.snp.makeConstraints { (make) in
//make.left.right.top.bottom.equalTo(0)
//make.width.equalTo(UIScreen.main.bounds.size.width)
//}

2、重寫preferredLayoutAttributesFitting

override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
self.setNeedsLayout()
self.layoutIfNeeded()

let size = self.contentView.systemLayoutSizeFitting(layoutAttributes.size)
var cellFrame = layoutAttributes.frame
cellFrame.size.height = size.height
layoutAttributes.frame = cellFrame
return layoutAttributes
}

UICollectionViewCell程式碼

//
//GAEstimatedCell.swift
//YYFramework
//
//Created by 侯佳男 on 2018/12/26.
//Copyright © 2018年 houjianan. All rights reserved.
//

import UIKit
import SnapKit

class GAEstimatedCell: UICollectionViewCell {

@IBOutlet weak var l: UILabel!
@IBOutlet weak var l1: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// 002
//self.contentView.snp.makeConstraints { (make) in
//make.left.right.top.bottom.equalTo(0)
//make.width.equalTo(UIScreen.main.bounds.size.width)
//}
}

// 001
override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
self.setNeedsLayout()
self.layoutIfNeeded()

let size = self.contentView.systemLayoutSizeFitting(layoutAttributes.size)
var cellFrame = layoutAttributes.frame
cellFrame.size.height = size.height
layoutAttributes.frame = cellFrame
return layoutAttributes
}
}

UIViewController程式碼

//
//GAEstimatedCollectionViewController.swift
//YYFramework
//
//Created by 侯佳男 on 2018/12/26.
//Copyright © 2018年 houjianan. All rights reserved.
//

import UIKit

class GAEstimatedCollectionViewController: UIViewController {

lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.estimatedItemSize = CGSize(width: kScreenWidth, height: 100)
layout.minimumLineSpacing = 0
layout.minimumInteritemSpacing = 10
let v = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout)
v.delegate = self
v.dataSource = self
v.backgroundColor = UIColor.lightGray
return v
}()

var data: [String] = ["YYBaseCollectionViewControllerYYBaseCollectionViewControllerYYBaseCollectionViewController", "2233", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewControllerYYBaseCollectionViewController", "2233", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewControllerYYBaseCollectionViewController", "2233", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewControllerYYBaseCollectionViewController", "2233", "YYBaseCollectionViewControllerYYBaseCollectionViewController", "YYBaseCollectionViewControllerYYBaseCollectionViewController"]

override func viewDidLoad() {
super.viewDidLoad()

self.view.addSubview(collectionView)
collectionView.snp.makeConstraints { (make) in
make.edges.equalTo(self.view)
}
collectionView.yy_register(nibName: GAEstimatedCell.identifier)
}

}

extension GAEstimatedCollectionViewController: UICollectionViewDelegate, UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: GAEstimatedCell.identifier, for: indexPath) as! GAEstimatedCell
cell.l.text = data[indexPath.row]
cell.l1.text = data[indexPath.row]
return cell
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return data.count
}
}