在数组中查找可重复的字符串位置

Question

我无法在数组中获得可重复的字符串位置。我的代码是这样的：

var startDates : [String] = ["06/11/2018", "16/11/2018", "26/11/2018", "06/11/2018"]
var nomor : [Int] = []
for date in startDates {
        if startDates.contains(where: {
            $0.range(of: "06/11/2018", options: .caseInsensitive) != nil
        }) == true {
            let nomornya = startDates.index(of: "06/11/2018")!
            nomor.append(nomornya)
        }
    }
    print("nomornya:\(nomor)")

结果：

nomornya:[0, 0, 0, 0]

我想要这样：

nomornya:[0, 3]

执行此操作的正确代码是什么？

Answer 1

您想要与特定日期匹配的项目的索引，因此请过滤索引：

let startDates = ["06/11/2018", "16/11/2018", "26/11/2018", "06/11/2018"]
let nomor = startDates.indices.filter{ startDates[$0] == "06/11/2018" } // [0, 3]

Answer 2

let date = "06/11/2018"
var matchingIndices = [Int]()
for (index, startDate) in startDates.enumerated() {
    if date == startDate {
        matchingIndices.append(index)
    }
}

您要遍历列表一次，注意匹配的索引。这应该符合您的预期输出。