Ios 如何从已实现的PLIST字典中访问项?
我从plist中提取了项目并将其实现到字典中,但是我不太确定如何从变量中展开并使这些项目可用。以下是我所拥有的:Ios 如何从已实现的PLIST字典中访问项?,ios,swift,uiviewcontroller,tableview,plist,Ios,Swift,Uiviewcontroller,Tableview,Plist,我从plist中提取了项目并将其实现到字典中,但是我不太确定如何从变量中展开并使这些项目可用。以下是我所拥有的: import UIKit class ViewController: UIViewController, UITableViewDataSource { // Loading in the PLIST file override func viewDidLoad() { super.viewDidLoad() } var courses
import UIKit
class ViewController: UIViewController,
UITableViewDataSource {
// Loading in the PLIST file
override func viewDidLoad() {
super.viewDidLoad()
}
var courses = loadCSCourses()
//variables
var courseData = courses["CS 1400"]
var shortDescription = courseData["ShortDescription"]
var courseKeys = Array(courses.keys)
@IBOutlet weak var mySwitch: UISwitch!
@IBOutlet weak var tableView: UITableView!
@IBAction func whenSwitchOn (sender:AnyObject) {
if (mySwitch.isOn){
self.tableView.reloadData()
}
}
func sortingCourseKeys() {
courseKeys.sort()
}
// The number of rows
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return courses!.count
}
// The number of cells in each row
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
//Naming the Title and Subtitle line
cell.textLabel?.text = "course name"
cell.detailTextLabel?.text = "course description"
cell.accessoryType = .checkmark
return cell
}
// Selecting and deslecting rows
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath){
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.text = courseKeys[indexPath.row]
if cell.contains(courseKeys[indexPath.row]) {
cell.accessoryType = .checkmark
}else{
cell.accessoryType = .none
}
return
}
}
func loadCSCourses() -> [String : [String : String]]? {
let pListFileURL = Bundle.main.url(forResource: "CSCourses", withExtension: "plist", subdirectory: "")
if let pListPath = pListFileURL?.path,
let pListData = FileManager.default.contents(atPath: pListPath) {
do {
let pListObject = try PropertyListSerialization.propertyList(from: pListData, options:PropertyListSerialization.ReadOptions(), format:nil)
guard let maybeCourses = pListObject as? [String : [String : String]] else {
return nil
}
return maybeCourses
} catch {
print("Error reading CSCourses plist file: \(error)")
return nil
}
}
return nil
}
我得到的错误是:
无法在属性初始值设定项中使用实例成员“courses”;属性初始值设定项在“self”可用之前运行
&
必须展开可选类型“[String:[String:String]]”的值,才能引用已包装基类型“[String:[String:String]]”的成员“subscript”
任何提示、链接或帮助都将不胜感激。谢谢大家。您面临的问题是,在初始化self之前,您正在使用一个类方法。您有几个选择: 重写init函数并在那里设置变量
override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
courses = loadCSCourses()
}
将变量设为惰性变量
lazy var courses = loadCSCourses()
将函数loadCSCourses设置为静态,尽管我不建议这样做
请记住您定义的方式:
var courseData = courses["CS 1400"]
var shortDescription = courseData["ShortDescription"]
var courseKeys = Array(courses.keys)
也太早了,在定义self之后,将其移动到init,或者遵循2。选择权