Swift Nested Function

Nested functions are functions defined within the body of another function in Swift programming language. They are a powerful feature of Swift, allowing you to organize and encapsulate code within your application.

Syntax

Here is the syntax for defining a nested function in Swift programming language:

func outerFunction() {
  // ...
  
  func innerFunction() {
    // inner function implementation
  }
}

Example

Here is an example of a nested function in Swift programming language:

func calculateSum(_ a: Int, _ b: Int, _ c: Int) -> Int {
  func add(_ x: Int, _ y: Int) -> Int {
      return x + y
  }
  
  let firstSum = add(a, b)
  let secondSum = add(firstSum, c)
  return secondSum
}

let result = calculateSum(3, 5, 7)
print(result) // Output: 15

Output

The output of this code is the sum of the three integers passed to the calculateSum function.

Explanation

In this example, we have defined a calculateSum method that takes in three integers as arguments. Within this method, we have defined a nested function called add that accepts two integer inputs and returns their sum. This add function is then used twice by the calculateSum method to calculate the sum of the three integers and return the final output.

Use

One of the main use cases for nested functions is to organize and streamline code within a larger function. Nested functions can be used to consolidate common functionality that is only ever used within the larger function. By doing this, the code can be more modular and easier to read and maintain.

Important Points

• Nested functions are functions defined within the body of another function in Swift programming language
• They can only be accessed within the enclosing function and are not visible to the outside world
• They are useful for organizing and streamlining code within a larger function
• They can consolidate common functionality that is only used within that larger function, resulting in modular and maintainable code
• The return type of the nested function must be inferred by the Swift compiler, or it must be explicitly specified within the function

Summary

Swift nested functions are powerful features that can help organize and encapsulate code into smaller, more manageable functions. They are perfect for consolidating common functionality that is only used within a larger function, making the code more modular and easier to maintain.