‏flatMap والتسلسل

وجهان لـ flatMap

تسطيح المصفوفات المتداخلة

let nested = [[1, 2], [3, 4], [5]]
let flat = nested.flatMap { $0 }
print(flat)  // [1, 2, 3, 4, 5]

استخدام flatMap لإنتاج تسلسلات

let nums = [1, 2, 3]
let expanded = nums.flatMap { [$0, $0 * 10] }
print(expanded)  // [1, 10, 2, 20, 3, 30]

إنشاء كل التركيبات

let suits = ["Hearts", "Spades"]
let ranks = ["A", "K"]
let deck = suits.flatMap { suit in ranks.map { "\($0) of \(suit)" } }
print(deck)  // ["A of Hearts", "K of Hearts", "A of Spades", "K of Spades"]

flatMap في مقابل compactMap

تسطيح الكلمات إلى محارف

let words = ["hi", "yo"]
let chars = words.flatMap { Array($0) }
print(chars)  // ["h", "i", "y", "o"]

ضم النتائج الفرعية

struct Team { let members: [String] }
let teams = [Team(members: ["Ann", "Bo"]), Team(members: ["Cy"])]
let all = teams.flatMap { $0.members }
print(all)  // ["Ann", "Bo", "Cy"]

تسلسل التحويلات

مسار معالجة كامل

let groups = [[1, 2, 3], [4, 5], [6]]
let result = groups
    .flatMap { $0 }
    .filter { $0 % 2 == 0 }
    .map { $0 * $0 }
    .reduce(0, +)
print(result)  // 4 + 16 + 36 = 56

استخدام flatMap ثم compactMap

let rows = [["1", "x"], ["3", "4"]]
let nums = rows
    .flatMap { $0 }
    .compactMap { Int($0) }
print(nums)  // [1, 3, 4]

الحفاظ على وضوح التسلسلات

let names = ["ann", "BO", "cy"]
let titled = names
    .map { $0.lowercased() }
    .map { $0.capitalized }
    .sorted()
print(titled)  // ["Ann", "Bo", "Cy"]

اختبار سريع

مراجعة