Swift数组按字母顺序和组顺序排序答案

【问题标题】：Swift array sort alphabetically and in group orderSwift数组按字母顺序和组顺序排序
【发布时间】：2018-09-09 20:49:05
【问题描述】：

我正在尝试按字母顺序和组名排序数组

我的清单是：

Name: A
Group: cats

Name: B
Group: dogs

Name: C
Group: cats

我已经按照姓名的字母顺序进行了排序，它向我显示了以下顺序：

A
cats

B
dogs

C
cats

但我有点偏头痛，试图按组对它们进行排序，例如：

A
cats

C
cats

B
dogs

到目前为止我尝试过的字母顺序和组顺序：

case alpha:
    results.sorted { $0.first_name < $1.first_name }
case grouped:
    results.sorted { $0.group_name == $1.group_name }

【问题讨论】：

您需要一个排序操作。在闭包中，如果名称相同，则按组比较，否则按名称比较
我有一个分段控件，我可以在其中选择排序的类型，所以它不能帮助我在单个排序操作中完成它。
因此，您可能需要基于分段控件的多个单一排序操作（如果您将所有目标放在您的问题中，这会有所帮助），但是您拥有的方式现在第一个排序被第二个排序覆盖了。您需要在一次排序操作中考虑这两个条件。
您的第二个排序闭包甚至无效，因为它不执行相对比较
好的，我现在编辑了我的问题。

标签： arrays swift sorting

【解决方案1】：

试试这个：

results.sorted {($0.group_name, $0.first_name) < ($1.group_name, $1.first_name)}

例子：

struct Item {
    var first_name: String
    var group_name: String
}

let results = [
    Item(first_name: "A", group_name: "cats"),
    Item(first_name: "B", group_name: "dogs"),
    Item(first_name: "C", group_name: "cats")
]
let sortedResult = results.sorted {($0.group_name, $0.first_name) < ($1.group_name, $1.first_name)}
print(sortedResult)
//->[SortGroups.Item(first_name: "A", group_name: "cats"), SortGroups.Item(first_name: "C", group_name: "cats"), SortGroups.Item(first_name: "B", group_name: "dogs")]

Carpsen90 当前代码失败的例子。

struct Animal {
    let Name: String
    let Group: String
}

let animals = [
    Animal(Name: "B", Group: "rats"),
    Animal(Name: "C", Group: "dogs"),
    Animal(Name: "E", Group: "cats"),
    Animal(Name: "B", Group: "dogs"),
    Animal(Name: "A", Group: "cats"),
    Animal(Name: "C", Group: "dogs"),
    Animal(Name: "E", Group: "cats"),
    Animal(Name: "A", Group: "dogs"),
    Animal(Name: "B", Group: "dogs"),
    Animal(Name: "B", Group: "dogs"),
    Animal(Name: "D", Group: "cats"),
    Animal(Name: "A", Group: "cats"),
    Animal(Name: "B", Group: "cats"),
    Animal(Name: "B", Group: "dogs"),
    Animal(Name: "D", Group: "rats"),
    Animal(Name: "A", Group: "rats"),
    Animal(Name: "B", Group: "dogs"),
    Animal(Name: "D", Group: "dogs"),
    Animal(Name: "A", Group: "dogs"),
    Animal(Name: "A", Group: "rats")
]

let result = animals.sorted(by: {$0.Group < $1.Group}).sorted(by: {$0.Group == $1.Group && $0.Name < $1.Name })
print("[\n  "+result.map {String(describing: $0)}.joined(separator: ",\n  ")+"\n]")

输出：

[
  Animal(Name: "E", Group: "cats"),
  Animal(Name: "A", Group: "dogs"),
  Animal(Name: "A", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "C", Group: "dogs"),
  Animal(Name: "C", Group: "dogs"),
  Animal(Name: "A", Group: "cats"),
  Animal(Name: "B", Group: "cats"),
  Animal(Name: "D", Group: "cats"),
  Animal(Name: "E", Group: "cats"),
  Animal(Name: "D", Group: "dogs"),
  Animal(Name: "A", Group: "cats"),
  Animal(Name: "A", Group: "rats"),
  Animal(Name: "A", Group: "rats"),
  Animal(Name: "B", Group: "rats"),
  Animal(Name: "D", Group: "rats")
]

对同一输入使用元组比较：

let result2 = animals.sorted {($0.Group, $0.Name) < ($1.Group, $1.Name)}
print("[\n  "+result2.map {String(describing: $0)}.joined(separator: ",\n  ")+"\n]")

输出：

[
  Animal(Name: "A", Group: "cats"),
  Animal(Name: "A", Group: "cats"),
  Animal(Name: "B", Group: "cats"),
  Animal(Name: "D", Group: "cats"),
  Animal(Name: "E", Group: "cats"),
  Animal(Name: "E", Group: "cats"),
  Animal(Name: "A", Group: "dogs"),
  Animal(Name: "A", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "B", Group: "dogs"),
  Animal(Name: "C", Group: "dogs"),
  Animal(Name: "C", Group: "dogs"),
  Animal(Name: "D", Group: "dogs"),
  Animal(Name: "A", Group: "rats"),
  Animal(Name: "A", Group: "rats"),
  Animal(Name: "B", Group: "rats"),
  Animal(Name: "D", Group: "rats")
]

【讨论】：

($0.group_name, $0.first_name) < ($1.group_name, $1.first_name) 这是tuple < tuple 吗？以前没见过。
@Fabian，请查看SE-0015 Tuple comparison operators。

【解决方案2】：

试试这个

struct Animal {
    let Name: String
    let Group: String
}

let a1 = Animal(Name: "A", Group: "cats")
let a2 = Animal(Name: "B", Group: "dogs")
let a3 = Animal(Name: "C", Group: "cats")

let animals = [a3, a2, a1]

let result = animals.sorted(by: {$0.Group < $1.Group}).sorted(by: {$0.Group == $1.Group && $0.Name < $1.Name })
result  //Prints [{Name "A", Group "cats"}, {Name "C", Group "cats"}, {Name "B", Group "dogs"}]

sorted 返回一个新数组 (result) 并且不对初始数组（动物）进行排序。

【讨论】：

我的代码实际上是在另一个数组（一个新数组）上执行此操作的，在我的情况下，问题是字符串键错误.. 上面的代码运行良好
很高兴能为您提供帮助，祝您周日愉快！
将您的animals 更改为let animals = [a1, a2, a3]，我得到[SortGroups.Animal(Name: "A", Group: "cats"), SortGroups.Animal(Name: "B", Group: "dogs"), SortGroups.Animal(Name: "C", Group: "cats")]，您的代码似乎没有正确排序数组。
还是错了。尝试添加let a4 = Animal(Name: "D", Group: "dogs") 和let animals = [a1, a2, a3, a4]。 $0.Group <= $1.Group && $0.Name < $1.Name 无法实现两个元素的字典顺序。
我的输出 [SortGroups.Animal(Name: "A", Group: "cats"), SortGroups.Animal(Name: "B", Group: "dogs"), SortGroups. Animal(Name: "C", Group: "cats"), SortGroups.Animal(Name: "D", Group: "dogs")] (Xcode 9.4.1).