[iOS] Array的sort, filter, map, reduce 函式

Sort

1.

var intArray = [342, 13, 12, 288, 3, 34, 2, 39, 596, 2]

intArray.sort()

print(intArray)

// output: [2, 2, 3, 12, 13, 34, 39, 288, 342, 596]

2.

var intArray = [342, 13, 12, 288, 3, 34, 2, 39, 596, 2]

intArray.sort(by: {$0 > $1})

print(intArray)

// output: [596, 342, 288, 39, 34, 13, 12, 3, 2, 2]

Filter

let intArray = [342, 13, 12, 288, 3, 34, 2, 39, 596, 2]

let newArray = intArray.filter({$0 % 2 == 0}) //過濾, 取偶數
        
print(newArray)

// output: [342, 12, 288, 34, 2, 596, 2]

Map

let intArray = [342, 13, 12, 288, 3, 34, 2, 39, 596, 2]

let newArray = intArray.map({$0 * 3}) //所有數值乘3倍
        
print(newArray)

// output: [1026, 39, 36, 864, 9, 102, 6, 117, 1788, 6

Reduce

let intArray = [342, 13, 12, 288, 3, 34, 2, 39, 596, 2]
        
let sum = intArray.reduce(0, {$0 + $1})  // sum從0開始, 所有數字的總和
        
print(sum)

// output: 1331