Swift collection type higher-order functions
Use of filter and reduce (swift 5.3)
filter
Filtering, the elements in the array can be filtered once according to a certain rule.
let numbers = [1, 3, 5, 7, 9] let filterNumbers = numbers.filter {$0 <5} print(filterNumbers)
The output is as follows
[1, 3]
reduce
Calculation, you can calculate the elements of the array
let animals1 = ["Dog", "Cat", "Pig"] let string = animals1.reduce("Dog", { // $0: result, $1: the value of the array return $0 == "Cat"? $1: $0 + "," + $1 }) print(string)
The output result is as follows
Dog,Dog,Cat,Pig
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