如何快速获取键值对元组数组？

Question

我有对元组数组 pickerDataVisitLocation.just 我想知道如何使用 uniqId ex 204 从我的数组中返回键值对位置

var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
var selectedIndex = pickerDataVisitLocation[1].uniqId
pickerDataVisitLocation[selectedIndex].location //<--fatal error: Index out of range

Answer 1

根据给定的代码：
试试这个

var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
let selectedIndex = pickerDataVisitLocation[1].uniqId
var location = ""

for item in pickerDataVisitLocation {
    if item.uniqId == selectedIndex {
        location = item.location
    }
}

print(location) //Will print Hospital here

Answer 2

利用Sequence的first(where:)方法

您可以利用Sequence 的first(where:) 来访问满足基于元组元素的第一个成员（uniqId）的布尔要求的数组的第一个元组元素。对于生成的元组元素，只需访问元组的第二个成员 (location)。

var pickerDataVisitLocation: [(uniqId: Int, location: String)] = 
    [(203, "Home"), (204, "Hospital"), (205, "Other")]

// say for a given uniqId 204
let givenId = 204
let location = pickerDataVisitLocation
               .first{ $0.uniqId == givenId }?.location ?? ""
print(location) // Hospital

---

如果找不到给定 id 的元组元素，则上述方法将导致结果字符串为空（由于 nil 合并运算符）。作为替代方案，您可以使用可选的绑定子句仅对来自.first 的非nil 返回进行处理：

var pickerDataVisitLocation: [(uniqId:Int,location:String)] = 
    [(203,"Home"),(204,"Hospital"),(205,"Other")]

// say for a given uniqId 204
let givenId = 204
if let location = pickerDataVisitLocation
                  .first(where: { $0.uniqId == givenId })?.location {
    print(location) // Hospital
}

---

可能的替代方法：考虑使用字典

最后，由于元组元素的第一个成员 uniqId 暗示了唯一成员，并且其类型 Int 为 Hashable，您可能需要考虑使用字典而不是元组数组.这将简化与给定唯一 Int id 关联的值的访问，但您将失去字典中“元素”（键值对）的顺序，因为字典是无序的集合。

var pickerDataVisitLocation = [203: "Home", 204: "Hospital", 205: "Other"]

// say for a given uniqId 204
let givenId = 204
if let location = pickerDataVisitLocation[givenId] {
    print(location) // Hospital
}

Answer 3

您可以尝试以下方法。

extension Array {
    func tupleWithId(id: Int) -> (uniqId:Int,location:String)? {
        let filteredElements = self.filter { (tuple) -> Bool in
            if let tuple = tuple as? (uniqId:Int,location:String) {
                return tuple.uniqId == id
            }
            return false
        }

        if filteredElements.count > 0 {
            let element = filteredElements[0] as! (uniqId:Int,location:String)
            return element
        }
        return nil
    }
}
var pickerDataVisitLocation:[(uniqId:Int,location:String)] = [(203,"Home"),(204,"Hospital"),(205,"Other")]
var selectedIndex = pickerDataVisitLocation[1].uniqId
pickerDataVisitLocation.tupleWithId(id: selectedIndex)?.location