Higher-Order Function in Swift

come let’s become lazier.

Don’t ignore the passages like your crush ❤️ignoring you.

What is the higher-order function?

It’s basically to make developer lazier than we are now or in other words, we can say Higher-order functions are function that already built-in

For sorting an array without any higher-order function, we use at least for loops with 6 or more lines that but with a higher-order function can do it in a single line with using just sort(by:>)

Note: I used fully shorthand method to explain here and I don't want you to make lazier, so I don’t upload any code in GitHub for you to copy and paste

Map :

What is the map function?

The map will loop over the collection and apply same operation in an array

let's start with comparing examples (like comparing traditional way with higher-order function way)

After applying the higher-order function

you can feel the difference from image size itself

• Here $0Swift’s closures shorthand notation
• mapwill loop over the collection and apply the same operation ($0 * 10)in an array and return an array

(NOTE: inside the {$0 } we can use any type of operation or even other higher-order function in it )

Map with a dictionary

After applying the higher-order function (SPD emergency )

• .values for selecting values of the dictionary
• .keys for selecting key of the dictionary

Flat Map

The FlatMapis basically just like .map(), except it filters out any nil values.

After applying the higher-order function. Image size speaks bro

I have one unknown use of FlatMap it is used to split the strings in an array

(Note: Don’t ask this traditional way code, I'm that much lazier)

• it will split the strings and ignores the NIL

CompactMap

Returns an array result of calling the given transformation with each element in the sequence.

Here is the use of CompactMap

It is used to take out Int values from an array of string and more

After applying the higher-order function

similarly, we can also do this for string

Filter

What is the filter function?

filter to loop over a collection and return an Array containing only those elements that match an include condition.

After applying the higher-order function

• Now filter will be checking like {1 % 2 == 0} here we will get False and the filter will not add the value to evenArray if true will be adding it

Let’s get all the numbers less than 5:( other usages)

Filtering Array of string using Filter

• The filter will be check like {"Abc".contains("Ab") now this will return true (if returns false filter will ignore the value )so the filter will be adding the value into filteredArray

contains : Returns a Boolean value indicating whether the sequence contains the given element.

Filter on the dictionary

After applying the higher-ordered function

HERE $0 is stands for key

$1 is stands for value

Filtering with an array of objects

step 1: creating an array of objects

(Note: Don’t get confused both are same code )

Step2: creating an array of abject using a struct, let's use a filter on it

• $0.rate to access the rate object. $0.booksName will access the booksNamearray

Reduce

What is Reduce function?

The reduce function allows you to combine all the elements in an array and return an single value

After getting more laziness (Applying the higher-order function)

• The first argument (1) always represents the partial result and not an element in the collection.
• Then it’s like 1 * 2 2*3 and so on

Another way of using reduce is likereduce(1,{$0 *$1}) with shorthand argument

• Here 1 again represents the partial result
• $0 -> it’s for starting value (it’s like n the current value)
• $1-> it’s for so on values (it’s like n the next value of current value )

For addition, we need to change the symbol (+) and The first argument

You know what we doing here

Some untold uses

max & min:

To find the maximum element in the sequence.

Much better always use .max to avoid more stress

just .max() is enough to find maximum element in the array

as? Int ?? 0 is to unwrap the optional

same like for minimum

After applying min function

Split :

split a string into pieces based on a given condition

In this, we separate all the " ”, but at some time we don’t need to split all the " ”so we can use maxSplits

split using shorthand argument

abs: (Be positive)

To change the negative values into positive values

If you pass positive value means will return a positive value

The reality, crush ignores even if you found the solution for COVID19..!

“ Every programmer is an author. “ — Sercan Leylek

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Tony Wilson