‏filter والمسندات

ما هي filter؟

مثال بسيط على filter

let numbers = [1, 2, 3, 4, 5, 6]
let evens = numbers.filter { $0 % 2 == 0 }
print(evens)  // [2, 4, 6]

تصفية السلاسل النصية

let words = ["hi", "swift", "go", "filter"]
let long = words.filter { $0.count > 3 }
print(long)  // ["swift", "filter"]

ما هو المسند؟

تسمية مسند

let isPositive: (Int) -> Bool = { $0 > 0 }
let data = [-2, 5, -1, 8]
print(data.filter(isPositive))  // [5, 8]

الجمع بين الشروط

let nums = [1, 2, 3, 4, 5, 6, 7, 8]
let picked = nums.filter { $0 % 2 == 0 && $0 > 4 }
print(picked)  // [6, 8]

تصفية البنى

struct Product { let name: String; let price: Int }
let items = [Product(name: "Pen", price: 2), Product(name: "Bag", price: 40)]
let cheap = items.filter { $0.price < 10 }
print(cheap.map { $0.name })  // ["Pen"]

filter في مقابل map

let n = [1, 2, 3, 4]
print(n.filter { $0 > 2 })  // [3, 4]  (subset, same type)
print(n.map { $0 > 2 })     // [false, false, true, true]

تسلسل filter و map

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

العدّ من دون الاحتفاظ بالعناصر

let votes = [true, false, true, true]
let yes = votes.filter { $0 }.count
print(yes)  // 3

تصفية القاموس

let ages = ["Ann": 30, "Bo": 17, "Cy": 22]
let adults = ages.filter { $0.value >= 18 }
print(adults.keys.sorted())  // ["Ann", "Cy"]

اختبار سريع

مراجعة