Swift：如果为空则隐藏标签

Posted 2023-03-04

【中文标题】Swift：如果为空则隐藏标签

【英文标题】：Swift : Hide Labels if Empty

【发布时间】：2015-08-05 01:24:09

【问题描述】：

我是 Swift 开发的新手，我正在开发一个将 JSON 文件解析为 UITableView 内的 CustomCell 的项目。我遇到的问题是我的标签是空的（因为我的可选展开），如果为空，我不希望它们显示在我的单元格中。这是我的代码：

import UIKit

class ScheduleTableViewController: UITableViewController, UITableViewDelegate, UITableViewDataSource 


    @IBOutlet var myTableView: UITableView!

    var nodeCollection = [Node]()

    var service:NodeService!

    override func viewDidLoad() 
        super.viewDidLoad()

        service = NodeService()
        service.getNodes 
            (response) in
            self.loadNodes(response["nodes"] as! NSArray)
        
    



    func loadNodes(nodes:NSArray)

        for node in nodes 

            var node = node["node"]! as! NSDictionary

            var field_class_day_value = node["field_class_day_value"] as! String

            var field_class_time_start_value = node["field_class_time_start_value"] as! String

            var field_class_time_end_value = node["field_class_time_end_value"] as! String

            var field_class_flex_header_value = node["field_class_flex_header_value"] as! String

            var title = node["title"] as!String

            var field_ages_value = node["field_ages_value"] as? String

            var field_class_footer_value = node["field_class_footer_value"] as? String

            var field_class_flex_footer_value = node["field_class_flex_footer_value"] as! String

            var field_class_instructor_nid = node["field_class_instructor_nid"] as? String



            if (field_class_day_value == "1")

                field_class_day_value = "Monday"

            else if (field_class_day_value == "2")

                field_class_day_value = "Tuesday"

            else if (field_class_day_value == "3")

                field_class_day_value = "Wednesday"

            else if (field_class_day_value == "4")

                field_class_day_value = "Thrusday"

            else if (field_class_day_value == "5")

                field_class_day_value = "Friday"

            else if (field_class_day_value == "6")

                field_class_day_value = "Saturday"

            else

                field_class_day_value = "Sunday"

            


            //convert time
            var dataStringStartTime = field_class_time_start_value
            var dataStringEndTime = field_class_time_end_value

            var dateFormatter = NSDateFormatter()
            var dateFormatter2 = NSDateFormatter()

            dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
            dateFormatter2.dateFormat = "h:mm a"



            let dateValueStartTime = dateFormatter.dateFromString(dataStringStartTime) as NSDate!
            let dateValueEndTime = dateFormatter.dateFromString(dataStringEndTime) as NSDate!

            let class_time_start_value = dateFormatter2.stringFromDate(dateValueStartTime)
            let class_time_end_value = dateFormatter2.stringFromDate(dateValueEndTime)

            let class_time_final = "\(class_time_start_value) - \(class_time_end_value)"

            let title_final = title.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())


            var nodeObj = Node(field_class_day_value: field_class_day_value,


                class_time_final: class_time_final,

                field_class_flex_header_value: field_class_flex_header_value,

                title_final: title_final,

                field_ages_value: field_ages_value,

                field_class_footer_value: field_class_footer_value,

                field_class_flex_footer_value: field_class_flex_footer_value,

                field_class_instructor_nid: field_class_instructor_nid)

            nodeCollection.append(nodeObj)

            dispatch_async(dispatch_get_main_queue()) 

                self.tableView.reloadData()

            

        

    


    override func didReceiveMemoryWarning() 
        super.didReceiveMemoryWarning()

    


    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int 

        return nodeCollection.count
    


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

        let node = nodeCollection[indexPath.row]
        cell.lbl_day_value.text = node.field_class_day_value
        cell.lbl_class_time_final.text = node.class_time_final
        cell.lbl_flex_header_value.text = node.field_class_flex_header_value
        cell.lbl_title.text = node.title_final
        cell.lbl_ages_value.text = node.field_ages_value
        cell.lbl_footer_value.text = node.field_class_footer_value
        cell.lbl_flex_footer_value.text = node.field_class_flex_footer_value
        cell.lbl_instructor_nid.text = node.field_class_instructor_nid

        return cell
    

【参考方案1】：

你可以试试这个：

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

    let node = nodeCollection[indexPath.row]
    cell.lbl_day_value.text = node.field_class_day_value
    cell.lbl_class_time_final.text = node.class_time_final
    cell.lbl_flex_header_value.text = node.field_class_flex_header_value
    cell.lbl_title.text = node.title_final
    cell.lbl_ages_value.text = node.field_ages_value
    cell.lbl_footer_value.text = node.field_class_footer_value
    cell.lbl_flex_footer_value.text = node.field_class_flex_footer_value
    cell.lbl_instructor_nid.text = node.field_class_instructor_nid

    //Get all your labels and check if they are now empty
    for view in cell.subviews 
        if let label = view as? UILabel 
            if label.text!.isEmpty 
                label.hidden = true
            
            else 
                label.hidden = false
            
        
    

    return cell

另外，作为一种标准做法，当您有这样的elseifs 时，使用开关看起来会更好：

switch field_class_day_value 
    case "1":
        field_class_day_value = "Monday"
    case "2":
        field_class_day_value = "Tuesday"
    case "3":
        field_class_day_value = "Wednesday"
    case "4":
        field_class_day_value = "Thrusday"
    case "5":
        field_class_day_value = "Friday"
    case "6":
        field_class_day_value = "Saturday"
    default:
        field_class_day_value = "Sunday"

示例：https://mega.nz/#!Q1xT3YJR!TP_BOCBVt6mCg1YAafo6EHQKIPqYKzT6scU6ZAPtgWg

【讨论】：

我忘了为非空标签设置 hidden = false 。这很重要，因为可以重复使用单元格。

抱歉回复晚了，我会尝试固定表格视图单元格的顶部和底部，并在每次隐藏标签时从约束中减去标签的高度。

抱歉，我不完全确定该怎么做。我一直在尝试将我的项目放到 github 上。

@JShuart 我可以快速创建一个示例项目来演示。

感谢 Caleb，我终于可以上传到 github...这是我的链接 github.com/jshuart/CultureShock-v.15.git