要在节中使用的对象的唯一值 [英] Unique value of object to use in section

问题描述

我有一个类，我需要获取流派对象，放入一个数组中，获取唯一值(因为我会有很多)并使用该数组填充 tableView 的部分.

I have a Class and I need to get genre object, put in an array, get unique value (because I will have many) and use the array to populate section of a tableView.

我有以下代码:

class Movie {
var name: String!
var plot: String!
var imageUrl: String!
var genre: String!

init(name: String, plot: String, img: String, genre: String) {

    self.name = name
    self.plot = plot
    self.imageUrl = img
    self.genre = genre




  }
 }


}

import UIKit

class ViewController: UIViewController, UITableViewDataSource,   UITableViewDelegate {

@IBOutlet weak var tableView: UITableView!

override func viewDidLoad() {
    super.viewDidLoad()

    tableView.delegate = self
    tableView.dataSource = self

}


var loadMovie = [Movie]()


let insertMovie = Movie(name: "Blow", plot: "Blow bla bla bla", img:     "", genre: "Action")
let insertMovie2 = Movie(name: "BLade", plot: "Blade bla bla bla", img: "", genre: "Action")
let insertMovie3 = Movie(name: "Inside Out", plot: "Blow bla bla bla", img: "", genre: "Kids")
let insertMovie4 = Movie(name: "Titanic", plot: "Blow bla bla bla", img: "", genre: "Drama")

loadMovie.append(insertMovie)
loadMovie.append(insertMovie2)
loadMovie.append(insertMovie3)
loadMovie.append(insertMovie4)


let unique = NSSet(array: loadMovie.map { $0.genre })

unique 返回唯一值(Action、Drama、Kids)，但是当我尝试获取部分时:

unique returns the unique value ( Action, Drama, Kids), but when I try to get section:

func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    return unique[section].genre

}

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

}

它不起作用.

我哪里错了?

推荐答案

每次重新加载表视图时按流派过滤电影的成本非常高.

Filtering the movies by genre each time the table view is reloaded is quite expensive.

这是一个使用标题(流派)名称数组和包含每个流派的 [Movie] 数组的字典的解决方案.

This is a solution using an array of header (genre) names and a dictionary containing a [Movie] array for each genre respectively.

var unique = [String]()
var loadMovie = [String:[Movie]]()

添加插入电影的方法.逻辑是:

Add a method to insert the movies. The logic is:

• 如果该类型存在，则将该类型的电影添加到字典中的 [Movie] 数组中.
• 如果流派不存在，请将流派添加到 unique 数组并将电影添加到字典中.

• If the genre exists, add the movie for that genre to the [Movie] array in the dictionary.
• If the genre does not exist, add the genre to the unique array and the movie to the dictionary.

func insertMovie(movie : Movie) {
  let genre = movie.genre
  if unique.contains(genre) {
    loadMovie[genre]!.append(movie)
  } else {
    unique.append(genre)
    loadMovie[genre] = [movie]
  }
}

现在插入电影

let movie = Movie(name: "Blow", plot: "Blow bla bla bla", img: "", genre: "Action")
insertMovie(movie)
let movie2 = Movie(name: "BLade", plot: "Blade bla bla bla", img: "", genre: "Action")
insertMovie(movie2)
let movie3 = Movie(name: "Inside Out", plot: "Blow bla bla bla", img: "", genre: "Kids")
insertMovie(movie3)
let movie4 = Movie(name: "Titanic", plot: "Blow bla bla bla", img: "", genre: "Drama")
insertMovie(movie4)

相关的数据源和委托方法是

The relevant data source and delegate methods are

override func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
  return unique[section]
}

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

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
  let genre = unique[section]
  return loadMovie[genre]!.count
}

在 cellForRowAtIndexPath 中填充单元格

...
   let genre = unique[indexPath.section]
   let movie = loadMovie[genre]![indexPath.row]
   cell.textLabel!.text = movie.name
...

另一种方法是数组数组

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