Comments

In programming, comments are used to annotate the code to provide extra information that isn't executed as part of the program. They can be used for various purposes such as explaining the functionality of a section of code, indicating TODOs, or providing metadata. Comments are highly useful for making code more readable and maintainable.

Swift Comments

Swift supports both single-line and multi-line comments.

Single-line Comments

Single-line comments start with two forward slashes (//):

// This is a single-line comment

You can also have inline comments:

let x = 42  // This is an inline comment

Multi-line Comments

Multi-line comments start with /* and end with */:

/* This is a
  multi-line comment */

Nested Multi-line Comments

Swift also allows nested multi-line comments, which is a feature not available in many C-family languages:

/* This is a multi-line comment
  /* This is a nested multi-line comment */
  Back to the first multi-line comment
*/

Best Practices for Comments

Descriptive Comments: Comments should describe why something is happening, not just what is happening. The code itself should be self-explanatory for the latter.

Keep Them Updated: Outdated comments that contradict the code are worse than no comments. Always keep comments updated when you update your code.

Don't Overuse: Excessive commenting can be counterproductive. If you feel the need to add a comment for a block of code to be understandable, it might be an indication that the code should be refactored.

Temporary Comments: Temporary comments (like TODO or FIXME) should be addressed as soon as possible. They should not accumulate and be left unresolved in the codebase.

Documentation Comments: For APIs and libraries, use documentation comments that can be parsed by documentation generators. In Swift, you can use triple slashes for this:

/// This function greets a person.
/// - Parameter name: The name of the person.
/// - Returns: A greeting string.
func greet(name: String) -> String {
   return "Hello, \(name)!"
}

Comments are an essential part of coding and, when used judiciously, can greatly enhance the readability and maintainability of your codebase.