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[英]How to create a predicate to filter array of enums with associated values in Swift?
[英]How can I sort an array of enums with associated values in Swift?
关于 StackOverflow 的第一个问题……请善待。 :)
我有一个带有关联值的枚举数组,我想按时间顺序对其进行排序。 其中一个值包含一个日期(作为字符串),该日期被显示并应用于排序。
这是目前的样子:
enum cellType {
case standard(text: String, icon: UIImage, hasChildren: Bool, reference: String)
case detailed(text: String, secondaryText: String, icon: UIImage, hasChildren: Bool, reference: String)
var identifier: String {
switch self {
case .standard: return "standardCell"
case .detailed: return "detailedCell"
}
}
}
var cellData: [cellType]
然后cellData
被填充一些cellType
s。 secondaryText
的值包含日期,如下所示:
print(cellData)
// [
// AppIdentifier.cellType.detailed(text: "Title A", secondaryText: "2017-10-20T10:04:00.000+02:00", icon: <UIImage: 0x60c0002a6660>, {12, 21}, hasChildren: false, reference: "40693"),
// AppIdentifier.cellType.detailed(text: "Title B", secondaryText: "2016-12-14T10:04:00.000+02:00", icon: <UIImage: 0x60c0002a6660>, {12, 21}, hasChildren: false, reference: "40632")
// AppIdentifier.cellType.detailed(text: "Title C", secondaryText: "2017-10-20T10:07:00.000+02:00", icon: <UIImage: 0x60c0002a6660>, {12, 21}, hasChildren: false, reference: "40694"),
// AppIdentifier.cellType.detailed(text: "Title D", secondaryText: "2017-11-16T10:34:00.000+02:00", icon: <UIImage: 0x60c0002a6660>, {12, 21}, hasChildren: false, reference: "40633"),
// AppIdentifier.cellType.detailed(text: "Title E", secondaryText: "2017-10-19T10:12:00.000+02:00", icon: <UIImage: 0x60c0002a6660>, {12, 21}, hasChildren: false, reference: "40682"),
// ]
当我尝试对数组进行排序时,以下内容显然太简单了:
var cellDataSorted = cellData.sorted(by: {$0.detailed.secondaryText < $1.detailed.secondaryText})
// Swift Compiler Error: enum element ’detailed’ cannot be referenced as an instance member
对这个数组进行排序的最佳方法是什么? 提前致谢!
(我是在电话上写这个的,所以.. 如有必要,请修复语法)
在 sorted 函数中使用以下代码:
if case .detailed(_, let date0, _, _, _) = $0, case .detailed(_, let date1, _, _, _) = $1 {
return date0 < date1
} else {
// One of them didn't have date (should never happen)
return true
}
您的问题是,您正在访问枚举的参数,就好像它是类/结构的实例一样。
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