对字符串数组进行排序并忽略大小写 [英] Sorting a String array and ignoring case

问题描述

下面的代码用于对字符串数组进行排序，如果它们全部为小写或全部为大写，但是我想在排序时忽略大小写.我该怎么办?以下是自定义类的数组.

The code below works for sorting an array of strings if they are all lowercase or all uppercase but I want to ignore case when I sort. How could I do this? The following is an array of a custom class.

resultListArray.sort({ $0.fileName.compare($1.fileName) == NSComparisonResult.OrderedAscending })

推荐答案

您可以使用String方法localizedCompare()

You can use String method localizedCompare()

更新: Xcode 11.5•Swift 5.2

let array = ["def","Ghi","Abc" ]

let sorted1 = array.sorted{$0.compare($1) == .orderedAscending} 
print(sorted1)  // ["Abc", "Ghi", "def"] this is case SENSITIVE!

let sorted2 = array.sorted{$0.localizedCompare($1) == .orderedAscending}
print(sorted2) // ["Abc", "def", "Ghi"]


// you can also use the String compare options parameter to give you more control when comparing your strings
let sorted3 = array.sorted{$0.compare($1, options: .caseInsensitive) == .orderedAscending }
print(sorted3)   // ["Abc", "def", "Ghi"]\n"

// which can be simplifyed using the string method caseInsensitiveCompare
let sorted4 = array.sorted{$0.caseInsensitiveCompare($1) == .orderedAscending}
print(sorted4) // ["Abc", "def", "Ghi"]\n"

// or localizedStandardCompare (case and diacritic insensitive)
// This method should be used whenever file names or other strings are presented in lists and tables where Finder-like sorting is appropriate. The exact sorting behavior of this method is different under different locales and may be changed in future releases. This method uses the current locale.
let array5 = ["Cafe B","Café C","Café A"]
let sorted5 = array5.sorted { $0.localizedStandardCompare($1) == .orderedAscending }
print(sorted5) // "["Café A", "Cafe B", "Café C"]\n"

---

您还可以实现自己的自定义排序/排序方法:

---

You can also implement your own custom sort/sorted methods:

extension Collection where Element: StringProtocol {
    public func localizedSorted(_ result: ComparisonResult) -> [Element] {
        sorted { $0.localizedCompare($1) == result }
    }
    public func caseInsensitiveSorted(_ result: ComparisonResult) -> [Element] {
        sorted { $0.caseInsensitiveCompare($1) == result }
    }
    public func localizedCaseInsensitiveSorted(_ result: ComparisonResult) -> [Element] {
        sorted { $0.localizedCaseInsensitiveCompare($1) == result }
    }
    /// This method should be used whenever file names or other strings are presented in lists and tables where Finder-like sorting is appropriate. The exact sorting behavior of this method is different under different locales and may be changed in future releases. This method uses the current locale.
    public func localizedStandardSorted(_ result: ComparisonResult) -> [Element] {
        sorted { $0.localizedStandardCompare($1) == result }
    }
}

---

extension MutableCollection where Element: StringProtocol, Self: RandomAccessCollection {
    public mutating func localizedSort(_ result: ComparisonResult) {
        sort { $0.localizedCompare($1) == result }
    }
    public mutating func caseInsensitiveSort(_ result: ComparisonResult) {
        sort { $0.caseInsensitiveCompare($1) == result }
    }
    public mutating func localizedCaseInsensitiveSort(_ result: ComparisonResult) {
        sort { $0.localizedCaseInsensitiveCompare($1) == result }
    }
    /// This method should be used whenever file names or other strings are presented in lists and tables where Finder-like sorting is appropriate. The exact sorting behavior of this method is different under different locales and may be changed in future releases. This method uses the current locale.
    public mutating func localizedStandardSort(_ result: ComparisonResult) {
        sort { $0.localizedStandardCompare($1) == result }
    }
}

---

用法:

---

Usage:

var array = ["def","Ghi","Abc" ]
array.caseInsensitiveSort(.orderedAscending)
array    // ["Abc", "def", "Ghi"]

---

---

要通过字符串属性对自定义对象进行排序，我们可以传递一个谓词以从元素中获取字符串，并在调用此方法时使用键路径:

---

---

To sort a custom object by a string property we can pass a predicate to get the string from the element and use a keypath when calling this method:

extension Collection {
    /// This method should be used whenever file names or other strings are presented in lists and tables where Finder-like sorting is appropriate. The exact sorting behavior of this method is different under different locales and may be changed in future releases. This method uses the current locale.
    public func localizedStandardSorted<T: StringProtocol>(by predicate: (Element) -> T, ascending: Bool = true) -> [Element] {
        sorted { predicate($0).localizedStandardCompare(predicate($1)) == (ascending ? .orderedAscending : .orderedDescending) }
    }
}

---

extension MutableCollection where Self: RandomAccessCollection {
    /// This method should be used whenever file names or other strings are presented in lists and tables where Finder-like sorting is appropriate. The exact sorting behavior of this method is different under different locales and may be changed in future releases. This method uses the current locale.
    public mutating func localizedStandardSort<T: StringProtocol>(by predicate: (Element) -> T, ascending: Bool = true) {
        sort { predicate($0).localizedStandardCompare(predicate($1)) == (ascending ? .orderedAscending : .orderedDescending) }
    }
}

---

用法:

---

Usage:

struct File {
    let id: Int
    let fileName: String
}

---

var files: [File] = [.init(id: 2, fileName: "Steve"),
                     .init(id: 5, fileName: "Bruce"),
                     .init(id: 3, fileName: "alan")]

let sorted = files.localizedStandardSorted(by: \.fileName)
print(sorted)  // [File(id: 3, fileName: "alan"), File(id: 5, fileName: "Bruce"), File(id: 2, fileName: "Steve")]

files.localizedStandardSort(by: \.fileName)
print(files)  // [File(id: 3, fileName: "alan"), File(id: 5, fileName: "Bruce"), File(id: 2, fileName: "Steve")]

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