The filter function takes a function that, given an element in array, returns Bool, indicating whether the element should be included in the resulting array. The filter method is declared as follows in Swift standard library:
public func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]
The definition is similar to the map method with the following differences:
- The
filterfunction takes a closure that receives elements of itself and returns aBoolvalue - The result of the
filtermethod will be an array of its own type
Let's examine the following code to understand how it works:
let numbers = [10, 30, 91, 50, 100, 39, 74]
let evenNumbers = numbers.filter { $0 % 2 == 0 } The resulting evenNumbers array will be [10, 30, 50, 100, 74].
Let's implement the filter function ourselves. In fact, its implementation is going to be similar to the implementation of map, except that it does not require a second generic specifying the codomain. Instead, it conditionally...