我有一个包含 10 个元素的 UItableView。我打开 Instruments 来捕获内存泄漏，当我滚动 tableView 时，它开始出现内存泄漏。在 Instruments 中，我试图找到导致泄漏的原因但无法弄清楚，它说“_NScontiguousstring”代表整个泄漏。

我找到了一些针对 Objective-C 的解决方案，他们检查“CellForRowAt”函数中的单元格是否为零。我不认为它对 Swift 有用，但我尝试了并且正如预期的那样它不起作用。

Memory Leak UITableView

我的问题是什么会导致这种内存泄漏？

我测试的设备；

11.3.1 上的 iPhone X

iPhone 6 11.2.5 Controller 类；

class TableViewController: UITableViewController {
let teamModel = TeamModel(uid: "adsada", name: "First Team ", idea: "idea 1", slogan: "Slogan 1", university: "dasda", image: "info", isActive: true)
let teamModel2 = TeamModel(uid: "adsada", name: "Team 2", idea: "idea 2", slogan: "adasd", university: "dasda", image: "info", isActive: true)
let teamModel3 = TeamModel(uid: "adsada", name: "Team 3", idea: "idea 3", slogan: "adasd", university: "dasda", image: "info", isActive: true)
let teamModel4 = TeamModel(uid: "adsada", name: "Team 4", idea: "idea 4", slogan: "adasd", university: "dasda", image: "info", isActive: true)
let teamModel5 = TeamModel(uid: "adsada", name: "Team 5", idea: "idea 5", slogan: "adasd", university: "dasda", image: "info", isActive: true)
let teamModel6 = TeamModel(uid: "adsada", name: "Team 6", idea: "idea 6", slogan: "adasd", university: "dasda", image: "info", isActive: true)
let teamModel7 = TeamModel(uid: "adsada", name: "Team 7", idea: "idea 7", slogan: "adasd", university: "dasda", image: "info", isActive: true)

var data: [TeamModel] = []
override func viewDidLoad() {
    super.viewDidLoad()
    tableView.register(mainTableCell.self, forCellReuseIdentifier: "mainTableCell")
    data = [teamModel,teamModel2,teamModel3,teamModel4,teamModel5,teamModel6,teamModel7]
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
    // #warning Incomplete implementation, return the number of sections
    return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of rows
    return data.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "mainTableCell", for: indexPath) as! mainTableCell
    let cell_data = data[indexPath.row]

    cell.cell_data = cell_data

    return cell
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 120
}
}

细胞类；

class mainTableCell: UITableViewCell{
var cell_data: TeamModel?{
    didSet{
        guard let unwrappedCell = cell_data else { return }
        if let url = unwrappedCell.imageURL{
            profileImage.image = UIImage(named: "info")
        } else{
            self.profileImage.image = UIImage(named: "info")
        }
        self.teamLbl.text = unwrappedCell.name
       mainBackground.backgroundColor = UIColor.gray
    }
}

let mainBackground: UIView = {
    let v = UIView()
    v.layer.cornerRadius = 8
    v.layer.masksToBounds = true
    return v
}()

var isVoteable: Bool = false

//let shadowView = ShadowView()

let profileImage: UIImageView = {
    let imageView = UIImageView()
    imageView.contentMode = .scaleAspectFill
    imageView.clipsToBounds = true
    imageView.layer.masksToBounds = true
    return imageView
}()

let teamLbl: UILabel = {
    let label = UILabel()
    label.textColor = UIColor.black
    label.numberOfLines = 1
    label.adjustsFontSizeToFitWidth = true
    return label
}()

let myVoteLbl: UILabel = {
    let l = UILabel()
    l.text = "Oyum: --"
    return l
}()
let voteBtn: UIButton = {
   let b = UIButton(type: .custom)
    b.setImage(UIImage(named: "info"), for: .normal)

    return b
}()
override init(style: UITableViewCellStyle, reuseIdentifier: String?){
    super.init(style: style, reuseIdentifier: reuseIdentifier)

    setupViews()
}
func setupViews() {

    self.backgroundColor = UIColor.white


    self.mainBackground.addSubview(profileImage)
    self.mainBackground.addSubview(teamLbl)
    self.mainBackground.addSubview(voteBtn)
    self.mainBackground.addSubview(myVoteLbl)

    //self.addSubview(shadowView)
    self.addSubview(mainBackground)
    self.backgroundColor = UIColor.clear

    profileImage.translatesAutoresizingMaskIntoConstraints = false
    teamLbl.translatesAutoresizingMaskIntoConstraints = false
    voteBtn.translatesAutoresizingMaskIntoConstraints = false
    myVoteLbl.translatesAutoresizingMaskIntoConstraints = false
    mainBackground.translatesAutoresizingMaskIntoConstraints = false
    //shadowView.translatesAutoresizingMaskIntoConstraints = false

}
override func layoutSubviews() {
    super.layoutSubviews()

   // self.setCircularImageView()
    mainBackground.anchor(self.topAnchor, left: self.leftAnchor, bottom: self.bottomAnchor, right: self.rightAnchor, topConstant: 10, leftConstant: 10, bottomConstant: 10, rightConstant: 10, widthConstant: 0, heightConstant: 0)
    // shadowView.anchor(self.topAnchor, left: self.leftAnchor, bottom: self.bottomAnchor, right: self.rightAnchor, topConstant: 5, leftConstant: 5, bottomConstant: 5, rightConstant: 5, widthConstant: 0, heightConstant: 0)

    profileImage.anchor(nil, left: self.mainBackground.leftAnchor, bottom: nil, right: nil, topConstant: 0, leftConstant: 10, bottomConstant: 0, rightConstant: 0, widthConstant: 60, heightConstant: 60)
    profileImage.anchorCenterYToSuperview()


    teamLbl.anchor(self.mainBackground.topAnchor, left: profileImage.rightAnchor, bottom: nil, right: self.voteBtn.leftAnchor, topConstant: 20, leftConstant: 20, bottomConstant: 0, rightConstant: 0, widthConstant: 0, heightConstant: 40)
    myVoteLbl.anchor(nil, left: profileImage.rightAnchor, bottom: self.mainBackground.bottomAnchor, right: nil, topConstant: 0, leftConstant: 20, bottomConstant: 20, rightConstant: 0, widthConstant: 0, heightConstant: 0)

    voteBtn.anchor(nil, left: nil, bottom: nil, right: self.mainBackground.rightAnchor, topConstant: 0, leftConstant: 0, bottomConstant: 0, rightConstant: 0, widthConstant: 80, heightConstant: 80)
    voteBtn.anchorCenterYToSuperview()
}

func setCircularImageView() {
    self.profileImage.layer.cornerRadius = CGFloat(roundf(Float(self.profileImage.frame.size.width / 2.0)))
}
required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}
}

编辑:我针对以下答案添加了 prepareForReuse 方法，但现在单元格只显示白色。难道我做错了什么？

    override func prepareForReuse() {
    super.prepareForReuse()

    teamLbl.text = ""
    myVoteLbl.text = ""
    profileImage.image = nil
}

我还将 cell_data 变量设置为“weak var cell_data: TeamModel? 并在 prepareForReuse() 方法中将其设为 nil，但仍然会出现相同的泄漏。

编辑 2:完整项目；

https://github.com/emreond/TableView-Memory-Leak-Project

编辑 3:我发现当我在 cell_data 的 didst 中添加 If check and change attributes 时，一些单元格 View 看起来已损坏。例如，当我更改 cell_data 中的 teamLbl 文本颜色时。在一些细胞中，它看起来已经毁了。

编辑 4:当我评论 anchor 代码以引用@Darp 的答案进行检查时，(我在屏幕上没有看到任何内容并且没有任何限制)它仍然继续泄漏。

编辑 5:我仍在处理此漏洞，但找不到任何解决方案。实际上，当 tableView 在屏幕上显示时，当我查看内存中的内容时，我看到内存中只有 8 个单元格，这看起来是正确的。

最佳答案

我对 _NSContiguousString 也有同样的问题。即使在只有一个标签的空应用程序中，它也会显示 48 字节的泄漏。

我不确定，但我猜测泄漏的原因可能是与 NSString 桥接(我还看到堆栈跟踪顶部的 [_SwiftNativeNSStringBase retain])。

我发现 NSString 本身可能被认为是 as a leaking object由 Instruments 提供，因为它已作为 Singleton 实现。

我自己的问题在这里:Memory leaks when assigning text to UILabel (iOS, Swift 4, XCode9)

关于ios - 滚动 UITableView 时仪器显示 "_NSContiguousstring"内存泄漏，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49871981/