ios - 我如何计算包含特定艺术家的文件？

Question

我从文件夹中获取数据。我有几个 UITableViewController。当我从艺术家 UITableViewController 移动到歌曲 UITableViewController 时，我希望它只显示特定艺术家的歌曲。我做到了，但我得到了一些空行。我认为这是因为我计算了所有 mp3 文件数组。我如何统计包含特定艺术家的文件？

    override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    // #warning Potentially incomplete method implementation.
    // Return the number of sections.
    return 1 ?? 0
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete method implementation.
    // Return the number of rows in the section.
    return contentArray.count ?? 0
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("artistTwo", forIndexPath: indexPath) as! SongsCellArtist

        var data = contentArray[indexPath.row]
        var documentFolder = fileManager.URLsForDirectory(NSSearchPathDirectory.DocumentDirectory, inDomains: NSSearchPathDomainMask.UserDomainMask)
        var urlForPlayer: NSURL!

        if var urlFromFolder: NSURL = documentFolder.first as? NSURL {
            urlForPlayer = urlFromFolder.URLByAppendingPathComponent(data)
        }
        println(urlForPlayer)

        var player = AVPlayerItem(URL: urlForPlayer)
        var nameSong: String!
        var nameAlbum: String!
        var nameArtistForCell: String!
        var dataForImage: NSData!

        var commonMetaData = player.asset.commonMetadata as! [AVMetadataItem]
        for item in commonMetaData {
            if item.commonKey == "title" {
                nameSong = item.stringValue
            }
            if item.commonKey == "album" {
                nameAlbum = item.stringValue
            }
            if item.commonKey == "artist" {
                nameArtistForCell = item.stringValue
            }
            if item.commonKey == "artwork" {
                dataForImage = item.dataValue
            }
        }

        var arrayFromCell: [String]!
        if nameArtistForCell == nameArtist {
        cell.nameSong?.text = nameSong

        if nameAlbum != nil {
            cell.artistAlbumName?.text = "\(nameArtistForCell) - \(nameAlbum)"
        } else {
            cell.artistAlbumName?.text = "\(nameArtistForCell)"
        }

        if dataForImage != nil {
            cell.imageSongs?.image = UIImage(data: dataForImage)

        }
    }

    return cell
}

Answer 1

如果您的内容没有填满屏幕，默认行为是在 TableView 的末尾显示空行。要删除这些空行，请在您的 viewDidLoad 调用中执行以下操作:

tableView.tableFooterView = UIView(frame: CGRectZero)

要过滤您的 Array 以查找确实有内容的项目，我建议您使用 filter 方法。仅包含 Strings 的 Array 示例:

let filteredArray = contentArray.filter { data in

var data = contentArray[indexPath.row]
var documentFolder = fileManager.URLsForDirectory(NSSearchPathDirectory.DocumentDirectory, inDomains: NSSearchPathDomainMask.UserDomainMask)
var urlForPlayer: NSURL!

if var urlFromFolder: NSURL = documentFolder.first as? NSURL {
    urlForPlayer = urlFromFolder.URLByAppendingPathComponent(data)
}

println(urlForPlayer)

var player = AVPlayerItem(URL: urlForPlayer)
var nameSong: String!
var nameAlbum: String!
var nameArtistForCell: String!
var dataForImage: NSData!

var commonMetaData = player.asset.commonMetadata as! [AVMetadataItem]
for item in commonMetaData {
    if item.commonKey == "title" {
        nameSong = item.stringValue
    }
    if item.commonKey == "album" {
        nameAlbum = item.stringValue
    }
    if item.commonKey == "artist" {
        nameArtistForCell = item.stringValue
    }
    if item.commonKey == "artwork" {
        dataForImage = item.dataValue
    }
}

// only add this to my new array, if I have all available meta data information
return nameSong != nil && nameAlbum && nil && nameArtistForcell != nil && dataForImage && nil
}

您可以阅读有关闭包表达式的更多信息 in the Docs .