在 tableView 的顶部添加一行

Question

我正在尝试在顶部的 tableView 中添加一行 let indexPath : [NSIndexPath] = [NSIndexPath(forRow: 0, inSection: 0)] parentTableView.insertRowsAtIndexPaths(indexPath, withRowAnimation: .Fade) 但它是将其添加到 tableView 的底部

这是我的代码:-

import UIKit

class ViewController: UIViewController , UITableViewDelegate, UITableViewDataSource,transferDelegate , UIViewControllerTransitioningDelegate{

var xibName : String = "HomepageFeedCellHeader"


var lords : [String] = ["name1","name2","name3"]

var queens : [String] = ["--","q1","q2"]

var desc : [String] = ["alpha","beta","gamma"]

var  menProfilePictures : [UIImage] = [UIImage(named: "DaarioNaharis")!,UIImage(named: "JaimeLannister")!,UIImage(named: "LordVarys")!]

@IBOutlet weak var postButton: UIButton!

@IBOutlet weak var parentTableView: UITableView!

@IBOutlet weak var pickImages: UIButton!

var a : ParentTableViewCell = ParentTableViewCell()

@IBOutlet weak var postTextView: UITextView!





override func viewDidLoad() {

    super.viewDidLoad()



    parentTableView.delegate = self
    parentTableView.dataSource = self


}




func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 1
}




func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return desc.count
}



func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = parentTableView.dequeueReusableCellWithIdentifier("ParentCell", forIndexPath: indexPath) as! ParentTableViewCell


    cell.transferingDelegate = self


    cell.feedPostUsername.text = lords[indexPath.row]
    cell.feedPostUserDetails.text = queens[indexPath.row]
    cell.feedPostDescription.text = desc[indexPath.row]
    cell.feedUserProfilePictures.image = menProfilePictures[indexPath.row]
    cell.selectionStyle = .None


    return cell


}

func transfer(itemNo : Int) {

    print("call recieved in viewController from item \(itemNo)")

    let imagePopOverScene = self.navigationController?.storyboard?.instantiateViewControllerWithIdentifier("ImagePopOverViewControllerVC_ID") as? ImagePopOverViewController

    print("itemNo in viewControlle \(itemNo)")
    if itemNo < 3{

        imagePopOverScene?.setImage = menProfilePictures[itemNo]

    }else{

        imagePopOverScene?.setImage = UIImage(named: "defaultProfilePic")

    }

    imagePopOverScene?.transitioningDelegate = self

    self.navigationController?.pushViewController(imagePopOverScene!, animated: true)

}

@IBAction func postBtnAction(sender: UIButton) {

    print("post btn action recieved")
    tableViewConfiguration()

}

func tableViewConfiguration(){



    parentTableView.beginUpdates()

    desc.append(postTextView.text!)
    menProfilePictures.append(UIImage(named: "defaultProfilePic")!)
    queens.append("--")
    lords.append("Anonymous")

    let indexPath : [NSIndexPath] = [NSIndexPath(forRow: 0, inSection: 0)]
    print(indexPath)
    parentTableView.insertRowsAtIndexPaths(indexPath, withRowAnimation: .Fade)

    tableView(parentTableView, cellForRowAtIndexPath: indexPath[0])

    parentTableView.endUpdates()
    parentTableView.reloadData()

    parentTableView.scrollToRowAtIndexPath(indexPath[0], atScrollPosition: UITableViewScrollPosition.Top, animated: true)


}


@IBAction func pickImagesAction(sender: UIButton) {





}

}

Answer 1

首先，永远不要在调用 insertRowsAtIndexPaths 之后调用 reloadData，因为 insertRowsAtIndexPaths 会隐式地重新排列 table 视图。

但这种情况掩盖了实际问题。

您正在将新项目附加到数据源数组 – 顺便说一句，您为什么不使用自定义结构而不是三个 (edit：甚至有四个！）数组——所以它们在最后 physically。

insertRowsAtIndexPaths 在索引 0 处正确插入项目，但随后重新加载 table 视图会根据数据源数组再次将项目移动到 table 的末尾。

解决方案：insert 数据源数组索引 0 处的项目而不是 append 它们。

编辑

建议使用自定义结构

在你的视图控制器之外声明

struct Avatar {

  let lord : String
  let queen : String
  let desc : String
  let profileImage : UIImage?

  init(lord: String, queen: String, desc: String, imageName: String) {
    self.lord = lord
    self.queen = queen
    self.desc = desc
    self.profileImage = UIImage(named: imageName)
  }
}

在ViewController声明一个数据源数组
```
var avatars = [Avatar]()
```

在viewDidLoad填充数据源数组

override func viewDidLoad() {
    super.viewDidLoad()
    parentTableView.delegate = self
    parentTableView.dataSource = self

    avatars = [Avatar(lord: "name1", queen: "--", desc: "alpha", imageName: "DaarioNaharis"),
               Avatar(lord: "name2", queen: "q1", desc: "beta", imageName: "JaimeLannister"),
               Avatar(lord: "name3", queen: "q2", desc: "gamma", imageName: "LordVarys")]
    parentTableView.reloadData()
 }

在numberOfRowsInSectionreturnavatars.count

在cellForRowAtIndexPath中分配属性

let avatar = avatars[indexPath.row]
cell.feedPostUsername.text = avatar.lord
cell.feedPostUserDetails.text = avatar.queen
cell.feedPostDescription.text = avatar.desc
cell.feedUserProfilePictures.image = avatar.profileImage

将tableViewConfiguration替换为

func tableViewConfiguration(){
    let newAvatar = Avatar(lord: "Anonymous", queen: "--", desc: postTextView.text!, imageName: "defaultProfilePic"
    avatars.insert(newAvatar, atIndex: 0)
    let indexPath = NSIndexPath(forRow: 0, inSection: 0)
    print(indexPath)
    parentTableView.insertRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
    parentTableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: .Top, animated: true)
}

在 tableView 的顶部添加一行

Adding a row to the top of a tableView

uitableview

ios

xcode7

swift2