ios - 如何正确解开 UILabels 中使用的变量？

Question

编辑1:在帖子底部添加了我的修订版 cellForRowAtIndexPath 代码

编辑2:添加了我的新EditorialElement代码

我很难正确展开 UILabel 文本输入，因此我的所有文本都显示“可选(作者姓名)”(例如，这是报纸的应用程序)。我尝试以不同的方式强制解开我的变量，但无法使其工作。

我的 UILabels 的文本输入是通过以下方式创建的。对应的类是“EditorialElement”，它有以下属性定义:

class EditorialElement: NSObject {

var title: String!           // title
var nodeID: Int?             // nid
var timeStamp: Int       // revision_timestamp
var imageURL: String?       // image_url
var author: String?          // author

var issueNumber: String!     // issue_int
var volumeNumber: String!    // volume_int

var articleContent: String! // html_content

/* To get an NSDate objec from Unix timestamp
var date = NSDate(timeIntervalSince1970: timeStamp) */

init(title: String, nodeID: Int, timeStamp: Int, imageURL: String, author: String, issueNumber: String, volumeNumber: String, articleContent: String) {
    self.title = title
    self.nodeID = nodeID
    self.timeStamp = timeStamp
    self.imageURL = imageURL
    self.author = author
    self.issueNumber = issueNumber
    self.volumeNumber = volumeNumber
    self.articleContent = articleContent
}

override func isEqual(object: AnyObject!) -> Bool {
    return (object as! EditorialElement).nodeID == self.nodeID
}

override var hash: Int {
    return (self as EditorialElement).nodeID!
}

}

然后，我使用此类从 JSON 文件中检索数据并将其解析为“editorialObjects”数组(对所有注释和错误的间距感到抱歉):

func populateEditorials() {
    if populatingEditorials {
        return
    }
    populatingEditorials = true

    Alamofire.request(GWNetworking.Router.Editorials(self.currentPage)).responseJSON() { response in
        if let JSON = response.result.value {
           /*
        if response.result.error == nil {
            */

            /* Creating objects for every single editorial is long running work, so we put that work on a background queue, to keep the app very responsive. */
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)) {


                /* Making an array of all the node IDs from the JSON file */
                var nodeIDArray : [Int]


                if (JSON .isKindOfClass(NSDictionary)) {

                    for node in JSON as! Dictionary<String, AnyObject> {

                    let nodeIDValue = node.0
                    var lastItem : Int = 0

                    self.nodeIDArray.addObject(nodeIDValue)

                    if let editorialElement : EditorialElement = EditorialElement(title: "init", nodeID: 0, timeStamp: 0, imageURL: "init", author: "init", issueNumber: "init", volumeNumber: "init", articleContent: "init") {

                editorialElement.title = node.1["title"] as! String
                editorialElement.nodeID = Int(nodeIDValue)

                let timeStampString = node.1["revision_timestamp"] as! String
                editorialElement.timeStamp = Int(timeStampString)!

                editorialElement.imageURL = String(node.1["image_url"])
                editorialElement.author = String(node.1["author"])
                editorialElement.issueNumber = String(node.1["issue_int"])
                editorialElement.volumeNumber = String(node.1["volume_int"])
                editorialElement.articleContent = String(node.1["html_content"])

                lastItem = self.editorialObjects.count

                print (editorialElement.nodeID)


                self.editorialObjects.addObject(editorialElement)


                /* Sorting the elements in order of newest to oldest (as the array index increases] */
                let timestampSortDescriptor = NSSortDescriptor(key: "timeStamp", ascending: false)
                self.editorialObjects.sortUsingDescriptors([timestampSortDescriptor])

                let indexPaths = (lastItem..<self.editorialObjects.count).map { NSIndexPath(forItem: $0, inSection: 0) }


               /*

                        nodeIDArray[nodeCounter] = jsonValue{nodeCounter}.string
                        let editorialInfos : EditorialElement = ((jsonValue as! NSDictionary].1["\(nodeIDArray[nodeCounter]]"] as! [NSDictionary]].map { EditorialElement(title: $0["title"] as! String, nodeID: $0["nid"] as! Int, timeStamp: $0["revision_timestamp"] as! Int, imageURL: $0["image_url"] as! String, author: $0["author"], issueNumber: $0["issue_int"] as! Int, volumeNumber: $0["volume_int"] as! Int, articleContent: $0["html_content"] as! String] // I am going to try to break this line down to simplify it and fix the build errors
*/


}

                print(self.editorialObjects.count)

            }
        }

                dispatch_async(dispatch_get_main_queue()) {
                    self.editorialsTableView.reloadData()
                }

                self.currentPage++
        }
    }

        self.populatingEditorials = false
}
}

然后我只在 cellForRowAtIndexPath 方法中使用这些对象作为标签:

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

    let row = indexPath.row

    let cell = tableView.dequeueReusableCellWithIdentifier(EditorialTableCellIdentifier, forIndexPath: indexPath) as! EditorialsTableViewCell

    let title = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).title

    let timeStamp = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).timeStamp
    let timeStampDateObject = NSDate(timeIntervalSince1970: NSTimeInterval(Int((editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).timeStamp)))
    timeStampDateString = dateFormatter.stringFromDate(timeStampDateObject)

    let imageURL = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).imageURL

    let author : String! = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).author!

    let issueNumber = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).issueNumber
    let volumeNumber = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).volumeNumber

    let articleContent = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).articleContent

    let nodeID = (editorialObjects.objectAtIndex(indexPath.row) as! EditorialElement).nodeID

    /* Unlike the Pictures Collection View, there is no need to create another Alamofire request here, since we already have all the content we want from the JSON we downloaded. There is no URL that we wish to place a request to to get extra content. */

    cell.editorialHeadlineLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleHeadline)
    cell.editorialHeadlineLabel.text = title

    cell.editorialAuthorLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
    cell.editorialAuthorLabel.text = author

    cell.editorialPublishDateLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
    cell.editorialPublishDateLabel.text = timeStampDateString

    return cell
}

我应该在哪里强制解包我的变量？

编辑 1:修改后的代码

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

    let row = indexPath.row

    guard let cell = tableView.dequeueReusableCellWithIdentifier(EditorialTableCellIdentifier, forIndexPath: indexPath) as? EditorialsTableViewCell else {
        print ("error: editorialsTableView cell is not of class EditorialsTableViewCell, we will use RandomTableViewCell instead")
        return tableView.dequeueReusableCellWithIdentifier(EditorialTableCellIdentifier, forIndexPath: indexPath) as! RandomTableViewCell
    }

    if let editorialObject = editorialObjects.objectAtIndex(indexPath.row) as? EditorialElement {
        // we just unwrapped editorialObject

        let title = editorialObject.title ?? "" // if editorialObject.title == nil, then we return an empty string.

        let timeStampDateObject = NSDate(timeIntervalSince1970: NSTimeInterval(editorialObject.timeStamp))
        let timeStampDateString = dateFormatter.stringFromDate(timeStampDateObject)

        let author = editorialObject.author ?? ""

        let issueNumber = editorialObject.issueNumber ?? ""
        let volumeNumber = editorialObject.volumeNumber ?? ""

        let articleContent = editorialObject.articleContent ?? ""

        let nodeID = editorialObject.nodeID ?? 0


        cell.editorialHeadlineLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleHeadline)
        cell.editorialHeadlineLabel.text = title

        cell.editorialAuthorLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
        cell.editorialAuthorLabel.text = String(author)

        cell.editorialPublishDateLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
        cell.editorialPublishDateLabel.text = timeStampDateString

    } else {

    }

    return cell
}

编辑2:新的EditorialElement代码

class EditorialElement: NSObject {

var title: String           // title
var nodeID: Int             // nid
var timeStamp: Int       // revision_timestamp
var imageURL: String       // image_url
var author: String       // author

var issueNumber: String     // issue_int
var volumeNumber: String    // volume_int

var articleContent: String // html_content

/* To get an NSDate objec from Unix timestamp
var date = NSDate(timeIntervalSince1970: timeStamp) */

init(title: String, nodeID: Int, timeStamp: Int, imageURL: String, author: String, issueNumber: String, volumeNumber: String, articleContent: String) {
    self.title = title
    self.nodeID = nodeID
    self.timeStamp = timeStamp
    self.imageURL = imageURL
    self.author = author
    self.issueNumber = issueNumber
    self.volumeNumber = volumeNumber
    self.articleContent = articleContent
}

override func isEqual(object: AnyObject!) -> Bool {
    return (object as! EditorialElement).nodeID == self.nodeID
}

override var hash: Int {
    return (self as EditorialElement).nodeID
}

}

Answer 1

有几件事。 1. 只有当您知道那里会有东西时，才应该强行拆开它们。但如果你对此非常有信心(或者你不希望/不希望应用程序在没有它们的情况下工作)，那么你应该从一开始就强制将它们打开。仅在代码中的任何地方写入 imageURL! 来执行 var imageURL: String? 是没有意义的。可选值的点是让您能够优雅地处理对象可能为零的情况。

无论如何，假设这对您来说是正确的结构，我要做的第一件事是 if let 返回索引处的对象。所以写:

如果让 element = editorialObjects.objectAtIndex(indexPath.row) 为？编辑元素

现在，您可以在整个行单元格中使用 element 作为 EditorialElement。从那里您可以决定如何/何时打开其他所有内容。

所以让作者:字符串! = (editorialObjects.objectAtIndex(indexPath.row) as!EditorialElement).author! 将变为

letauthor = element.author! 或者您可以if let 避免崩溃并处理为零的情况。 if letauthor = element.author {//做某事 }