Swift：按字母顺序对对象数组进行排序

Question

我有这个：

class Movies {
  Name:String
  Date:Int
}

和一系列[电影]。 如何按名称的字母顺序对数组进行排序？ 我试过了：

movieArr = movieArr.sorted{ $0 < $1 }

和

movieArr = sorted(movieArr)

但这不起作用，因为我没有访问 Movies 的 name 属性。

Answer 1

在传递给sort的闭包中，比较要作为排序依据的属性。 像这样：

movieArr.sorted { $0.name < $1.name }

或在您想要绕过案例的情况下执行以下操作：

movieArr.sorted { $0.name.lowercased() < $1.name.lowercased() }

旁注：通常只有类型以大写字母开头； 我建议使用name和date ，而不是Name和Date 。

---

例如，在操场上：

class Movie {
    let name: String
    var date: Int?

    init(_ name: String) {
        self.name = name
    }
}

var movieA = Movie("A")
var movieB = Movie("B")
var movieC = Movie("C")

let movies = [movieB, movieC, movieA]
let sortedMovies = movies.sorted { $0.name < $1.name }
sortedMovies

sortedMovies将按顺序[movieA, movieB, movieC]

Swift5 更新

channelsArray = channelsArray.sorted { (channel1, channel2) -> Bool in
            let channelName1 = channel1.name
            let channelName2 = channel2.name
            return (channelName1.localizedCaseInsensitiveCompare(channelName2) == .orderedAscending)

Answer 2

使用 Swift 3，您可以选择以下方法之一来解决您的问题。

---

1. 对不符合Comparable协议的Movie类使用sorted(by:​)

如果你的Movie类不符合Comparable协议，你必须在你的闭包中指定你希望使用 Array 的sorted(by:​)方法的属性。

Movie类声明：

import Foundation

class Movie: CustomStringConvertible {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) {
        self.name = name
        self.date = date
    }

}

用法：

let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted(by: { $0.name < $1.name })
// let sortedMovies = movies.sorted { $0.name < $1.name } // also works

print(sortedMovies)

/*
prints: [Avatar, Piranha II: The Spawning, Titanic]
*/

---

2. 将sorted(by:​)与符合Comparable协议的Movie类一起使用

但是，通过使您的Movie类符合Comparable协议，当您想要使用 Array 的sorted(by:​)方法时，您可以获得更简洁的代码。

Movie类声明：

import Foundation

class Movie: CustomStringConvertible, Comparable {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) {
        self.name = name
        self.date = date
    }

    static func ==(lhs: Movie, rhs: Movie) -> Bool {
        return lhs.name == rhs.name
    }

    static func <(lhs: Movie, rhs: Movie) -> Bool {
        return lhs.name < rhs.name
    }

}

用法：

let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted(by: { $0 < $1 })
// let sortedMovies = movies.sorted { $0 < $1 } // also works
// let sortedMovies = movies.sorted(by: <) // also works

print(sortedMovies)

/*
 prints: [Avatar, Piranha II: The Spawning, Titanic]
 */

---

3. 对符合Comparable协议的Movie类使用sorted()

通过使您的Movie类符合Comparable协议，您可以使用 Array 的sorted()方法作为sorted(by:​)的替代方法。

Movie类声明：

import Foundation

class Movie: CustomStringConvertible, Comparable {

    let name: String
    var date: Date
    var description: String { return name }

    init(name: String, date: Date = Date()) {
        self.name = name
        self.date = date
    }

    static func ==(lhs: Movie, rhs: Movie) -> Bool {
        return lhs.name == rhs.name
    }

    static func <(lhs: Movie, rhs: Movie) -> Bool {
        return lhs.name < rhs.name
    }

}

用法：

let avatarMovie = Movie(name: "Avatar")
let titanicMovie = Movie(name: "Titanic")
let piranhaMovie = Movie(name: "Piranha II: The Spawning")

let movies = [avatarMovie, titanicMovie, piranhaMovie]
let sortedMovies = movies.sorted()

print(sortedMovies)

/*
 prints: [Avatar, Piranha II: The Spawning, Titanic]
 */

Answer 3

let sortArray =  array.sorted(by: { $0.name.lowercased() < $1.name.lowercased() })

Answer 4

对于那些使用 Swift 3 的人，接受答案的等效方法是：

movieArr.sorted { $0.Name < $1.Name }

Answer 5

由于未能使用基于语言环境的比较进行排序，这些答案中的大多数都是错误的。 看看 localizedStandardCompare()

Answer 6

排序数组 Swift 4.2

arrayOfRaces = arrayOfItems.sorted(by: { ($0["raceName"] as! String) < ($1["raceName"] as! String) })

Answer 7

*import Foundation
import CoreData


extension Messages {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<Messages> {
        return NSFetchRequest<Messages>(entityName: "Messages")
    }

    @NSManaged public var text: String?
    @NSManaged public var date: Date?
    @NSManaged public var friends: Friends?

}

    //here arrMessage is the array you can sort this array as under bellow 

    var arrMessages = [Messages]()

    arrMessages.sort { (arrMessages1, arrMessages2) -> Bool in
               arrMessages1.date! > arrMessages2.date!
    }*