14. How to use inout in Swift?

It will take about 1 minutes to finish reading this article.

In Swift, the inout keyword is used for function parameters, allowing a function to modify the value of the passed-in parameter, with these modifications affecting the original passed-in argument. Using the inout keyword enables a function to pass a reference to a parameter rather than a copy, allowing the function to change the value of the passed-in parameter. Here’s what inout does:

1. Modifying the value of the passed-in parameter: By using the inout keyword, a function can modify the value of the passed-in parameter, rather than just a local copy within the function.

   func updateValue(_ value: inout Int) {
       value += 1
   }
   
   var myValue = 5
   updateValue(&myValue)
   print(myValue) // Prints 6

2. Passing a reference instead of a value: By passing a reference to the parameter, the function can directly modify the original passed-in parameter without the need to create a copy. This is particularly useful when you need to modify a parameter and want those modifications to affect the original value.

3. Improving performance: By passing a reference instead of a value, unnecessary copies can be avoided, thus improving the performance and memory efficiency of the function.

Therefore, using the inout keyword allows a function to handle passed-in parameters more flexibly, enabling the function to modify the value of the original passed-in parameter rather than just manipulating a copy of the parameter.