[Swift] Collection Type (3)Dictionary

Swift의 Dictionary타입은 Foundation의 NSDictionary를 bridge한 타입.

빈 Dictionary 생성

var namesOfIntegers = [Int: String]()
namesOfIntegers[16] = "sixteen"

namesOfIntegers = [:]

 

리터럴로 Dictionary 생성

var airports: [String: String] = = ["YYZ": "Toronto Pearson", "DUB": "Dublin"]

 

Dictionary 접근, 변경

print("The airports dictionary contains \(airports.count) items.")

// 빈 Dictionary 확인
if airports.isEmpty {
    print("The airports dictionary is empty.")
} else {
    print("The airports dictionary is not empty.")
}

// 값 할당
airports["LHR"] = "London"

 

Array로부터 Grouping된 Dictionary 생성

let students = ["Kofi", "Abena", "Efua", "Kweku", "Akosua"]
let studentsByLetter = Dictionary(grouping: students, by: { $0.first! })

print(studentsByLetter)
// ["K": ["Kofi", "Kweku"], "A": ["Abena", "Akosua"], "E": ["Efua"]]