iOS Swift中：如何存储数组中所有重复值的索引？

举个例子，我有这个数组：

let dates = ["01/02/16", "02/02/16", "03/02/16", "01/02/16", "02/02/16"] 

我喜欢做的是将每个Stringdate作为关键字存储在字典中，对于每个重复的键，我喜欢将它的索引存储为数组，并将其与重复键相关联。

例如， 01/02/16发生在索引0和3 。 02/02/16发生在指数1和4 。

我喜欢有一个这样的字典：

 [ "01/02/16": [0, 3], "02/02/16": [2, 4], "03/02/16": [1] ] 

我知道如何跟踪有多less重复的条目是这样的：

 let dates = ["01/02/16", "01/02/16", "02/02/16", "03/02/16"] var dateCounts:[String:Int] = [:] for date in dates { dateCounts[date] = (dateCounts[date] ?? 0) + 1 } for (key, value) in dateCounts { print("\(key) occurs \(value) time/s") } 

但是，我不确定如何跟踪重复的索引？

Answer 1

试试这个

 import UIKit class ViewController: UIViewController { var duplicatedDict : [String:[Int]] = [:] let dates = ["01/02/16", "01/02/16", "02/02/16", "03/02/16"] override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. for (index,dateString) in dates.enumerated() { if(duplicatedDict[dateString] == nil){ duplicatedDict[dateString] = [index] }else{ duplicatedDict[dateString]?.append(index) } } debugPrint(duplicatedDict) } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } } 

控制台日志输出

[“02/02/16”：[2]，“01/02/16”：[0，1]，“03/02/16”：[3]]

希望这可以帮助