Swift:按字母顺序排列对象数组

Question

我有这个:

class Movies {
  Name:String
  Date:Int
}

还有一组[电影].如何按名称按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,因为我没有访问电影的名称属性.

Answer 1

在传递给的闭包中sort,比较要排序的属性.像这样:

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

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

例如,在操场上:

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

sortedMovies 将在订单中 [movieA, movieB, movieC]

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.使用sorted(by:?)具有Movie不符合类Comparable的协议

如果您的Movie类不符合Comparable协议,则必须在闭包中指定您希望使用Array 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.使用符合协议sorted(by:?)的Movie类Comparable

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,您可以拥有一个非常简洁的代码.

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.使用符合协议sorted()的Movie类Comparable

通过使您的Movie类符合Comparable协议,您可以使用Array的sorted()方法作为替代sorted(by:?).

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的人来说,接受答案的等效方法是:

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