滚动

Question

我承认在Swift中使用这些自定义标头失败。我已经尝试了几天来防止部分标题内的标签和图像重复。基本上在滚动时，标题内的标签/图像重复并叠加在一起。

有人会因为上帝的爱而向我解释为什么会发生这种情况以及如何解决它。

圆形图像不断创建图像并将它们放在上一个图像上，与名称和日期标签相同!!

这是我的ViewController：

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource  {

    @IBOutlet weak var navigationBar: UINavigationItem!
    @IBOutlet weak var tableView: UITableView!
    var list = []
    var audioPlayer:AVAudioPlayer!
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func getListBro() -> NSArray {
        return list
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        tableView.dataSource = self;
        tableView.delegate = self;
        self.tableView.rowHeight = UITableViewAutomaticDimension


        let streamURL = NSURL(string: "http://192.241.174.8:8000/beat-stream-all/")!

        let stuff = GetBeatStream(url:streamURL)
        self.tableView.rowHeight = UITableViewAutomaticDimension;
        self.tableView.estimatedRowHeight = 50.0; //
        stuff.downloadJSONFromURL {
            (let jsonDictionary) in
                if let jsonList = jsonDictionary["results"] as? NSArray {
                    self.list = jsonList
                }


                let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
                dispatch_async(dispatch_get_global_queue(priority, 0)) {
                    // do some task
                    dispatch_async(dispatch_get_main_queue()) {
                        // update some UI
                        self.tableView.reloadData()
                    }
                }
        }
    }//end view did load



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

        let cell = tableView.dequeueReusableCellWithIdentifier("streamCell", forIndexPath: indexPath) as! StreamTableViewCell

        cell.beatCover.image = UIImage(named: "imgres")

        if let id = list[indexPath.section] as? NSDictionary {
            if let beatID = id["id"] as? NSInteger {
                cell.setID(beatID)
            }
        }

        if let beat_cover = list[indexPath.section] as? NSDictionary {
            if let beat_cover_image = beat_cover["beat_cover"] as? String {
                cell.beatCover.downloadImageFrom(link: beat_cover_image, contentMode: UIViewContentMode.ScaleToFill)  //set your image from link array.
            }
        }



        if let audio = list[indexPath.section] as? NSDictionary {
            if let audio_url = audio["audio"] as? String {
                    cell.url = audio_url
                    cell.buildPlayer()
            }
        }

        return cell
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 1
    }

    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return list.count
    }

    func tableView(tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {


        let beatAuthorLabel = UILabel(frame: CGRectMake(55, 5, 200, 40))

        //USER PIC
        let profilePictureImageView = UIImageView(frame: CGRectMake(5, 5, 40, 40));
        profilePictureImageView.layer.borderWidth = 0
        profilePictureImageView.layer.masksToBounds = false
        profilePictureImageView.layer.borderColor = UIColor.blackColor().CGColor
        profilePictureImageView.layer.cornerRadius = profilePictureImageView.frame.height/2
        profilePictureImageView.clipsToBounds = true
        profilePictureImageView.layer.masksToBounds = true

        profilePictureImageView.image = UIImage(named: "imgres")  //set placeholder image first.

        if let userPicSection = list[section] as? NSDictionary {
            if let artist = userPicSection["artist"] as? NSDictionary {
                if let profilePic = artist["profile_pic"] as? String {
                    profilePictureImageView.downloadImageFrom(link: profilePic, contentMode: UIViewContentMode.ScaleAspectFit) 
                }
            }
        }


        if let nameSection = list[section] as? NSDictionary {
            if let name = nameSection["artist"] as? NSDictionary {
                if let adminName = name["admin_name"] as? NSString {
                    print(adminName)
                    beatAuthorLabel.text = adminName as String
                    beatAuthorLabel.font = UIFont(name: beatAuthorLabel.font.fontName, size: 14)
                }
            }
        }






        var dateLabel = UILabel(frame: CGRectMake(225, 5, 200, 40))
        if let created = list[section] as? NSDictionary {
            if let date = created["created_at"] as? String {
                dateLabel.text = date as String
                dateLabel.font = UIFont(name: dateLabel.font.fontName, size: 8)
            }
        }

        let header: UITableViewHeaderFooterView = view as! UITableViewHeaderFooterView
        header.contentView.addSubview(beatAuthorLabel)
        header.contentView.addSubview(dateLabel)
        header.contentView.addSubview(dateLabel)
        header.contentView.addSubview(profilePictureImageView)
        header.contentView.backgroundColor = UIColor(red: 179/255, green: 194/255, blue: 191/255, alpha:1)
        header.textLabel!.textColor = UIColor.whiteColor()
        header.alpha = 1
    }



    func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 50
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        let indexPath = tableView.indexPathForSelectedRow
        let currentCell = tableView.cellForRowAtIndexPath(indexPath!)! as! StreamTableViewCell
        currentCell.player.play()
    }

    func tableView(tableView: UITableView, didEndDisplayingCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
        let leavingCell = cell as! StreamTableViewCell
        leavingCell.player.pause()
    }
}

Answer 1

标题视图（如单元格）重用。因此，当表视图向您发送tableView(_:willDisplayHeaderView:)时，可能不是您第一次收到该标题视图的消息。然而，每次收到消息时，都会向其添加四个子视图。

根本不要实施tableView(_:willDisplayHeaderView:forSection:)。

相反，请创建UITableViewHeaderFooterView的子类，其中包含不同子视图的属性。这就像您创建名为UITableViewCell的{​​{1}}的子类一样。也许你可以调用你的标题子视图类StreamTableViewCell。然后，您有两个选项来设置标题视图的子视图。

选项1：在StreamSectionHeaderView中，创建标题视图的子视图（并将它们存储在实例属性中并将其添加为子视图）。这基本上就是您现在在StreamSectionHeaderView.initWithFrame(_:)中所做的事情，但您可以将大部分代码移到tableView(_:willDisplayHeaderView:forSection:)类中。使用StreamSectionHeaderView在表格视图中注册StreamSectionHeaderView课程。

选项2：在XIB中设计标题视图及其子视图（您无法在故事板中执行此操作），将子视图连接到UITableView.registerClass(_:forHeaderFooterViewReuseIdentifier:)属性（必须为StreamSectionHeaderView s in这种情况），并使用IBOutlet在表格视图中注册XIB。

要生成部分，请通过调用UITableView.registerNib(_:forHeaderFooterViewReuseIdentifier:)实施tableView(_:viewForHeaderInSection:)，然后配置标题视图的子视图，这些子视图在tableView. dequeueReusableHeaderFooterViewWithIdentifier(_:)返回时已存在。

更新

这是您的dequeueReusableHeaderFooterViewWithIdentifier(_:)，假设您要在代码中设置其子视图：

StreamSectionHeaderView

然后，在您的表视图控制器中：

class StreamSectionHeaderView: UITableViewHeaderFooterView {

    // Make these IBOutlets if you design StreamSectionHeaderView in a XIB.
    var beatAuthorLabel = UILabel(frame: CGRectMake(55, 5, 200, 40))
    var profilePictureImageView = UIImageView(frame: CGRectMake(5, 5, 40, 40))
    var dateLabel = UILabel(frame: CGRectMake(225, 5, 200, 40))

    init(frame: CGRect) {
        profilePictureImageView.layer.borderWidth = 0
        profilePictureImageView.layer.masksToBounds = false
        profilePictureImageView.layer.borderColor = UIColor.blackColor().CGColor
        profilePictureImageView.layer.cornerRadius = profilePictureImageView.frame.height/2
        profilePictureImageView.clipsToBounds = true
        profilePictureImageView.layer.masksToBounds = true
        profilePictureImageView.image = UIImage(named: "imgres")

        beatAuthorLabel.font = UIFont(name: beatAuthorLabel.font.fontName, size: 14)
        dateLabel.font = UIFont(name: dateLabel.font.fontName, size: 8)

        contentView.addSubview(beatAuthorLabel)
        contentView.addSubview(dateLabel)
        contentView.addSubview(profilePictureImageView)
        contentView.backgroundColor = UIColor(red: 179/255, green: 194/255, blue: 191/255, alpha:1)
        textLabel!.textColor = UIColor.whiteColor()
        alpha = 1
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

}