将密钥与 iOS swift 4 中的字典数组进行比较

Question

我正在尝试将studentId与具有多个学生ID的字典数组进行比较。我需要获取与特定学生ID匹配的字典。任何人都可以提出完美的解决方案。我是斯威夫特的新手。

"students" : [
{
"studentId" : "STUDENT123456789",
"middleName" : "Evangeline",
"firstName" : "Dia",
"rollNo" : "1001",
"studentClass" : {
"className" : "Grade 10",
"classId" : "CLASS123456789",
}
}
{
"studentId" : "STUDENT14354678960",
"middleName" : "Joseph",
"firstName" : "Parker",
"rollNo" : "1002",
"studentClass" : {
"className" : "Grade 10",
"classId" : "CLASS15468975467",
}
}
]

我有学生数组，这是一个字典数组。现在，我必须将学生 ID 与包含多个学生 ID 的现有数组进行比较。因此，当它与学生ID匹配时，我需要获取该特定的字典数据。 例如，我将学生 ID 作为"STUDENT14354678960"，因此我需要获取包含与此 ID 相关的数据。

Answer 1

使用first，它返回找到的第一个对象或nil

if let student = students.first(where: {$0["studentId"] as! String == "STUDENT123456789"}) {
print(student["firstName"])
} else {
print("not found")
}

---

强烈建议对学生数据使用自定义结构或类，例如

let jsonString = """
{"students" : [
{"studentId" : "STUDENT123456789", "middleName" : "Evangeline", "firstName" : "Dia", "rollNo" : "1001", "studentClass" : { "className" : "Grade 10", "classId" : "CLASS123456789"}},
{"studentId" : "STUDENT14354678960", "middleName" : "Joseph", "firstName" : "Parker", "rollNo" : "1002", "studentClass" : {"className" : "Grade 10", "classId" : "CLASS15468975467"}}
]}
"""
struct Root : Decodable {
let students : [Student]
}
struct Student : Decodable {
let studentId, middleName, firstName, rollNo : String
let studentClass : StudentClass
}
struct  StudentClass : Decodable {
let className, classId : String
}
let data = Data(jsonString.utf8)
do {
let result = try JSONDecoder().decode(Root.self, from: data)
let students = result.students
if let student = students.first(where: {$0.studentId == "STUDENT123456789" }) {
print(student)
}
} catch {
print(error)
}

Answer 2

您可以使用 where 和闭包：

let search = students.first { (element) -> Bool in
if let dict = element as? [String:Any] {
return dict["studentId"] == yourID
}
}