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Swift Subscripts

Subscripts in Swift allow us to define shortcuts for accessing elements of a collection, list, or sequence. With subscripts, we can provide our own custom index notation for a specific type, just like we do in arrays and dictionaries.

Syntax

The syntax for defining a subscript in Swift is as follows:

subscript(index: Int) -> Int {
    get {
        // Return value corresponding to the index
    }
    set(newValue) {
        // Set the new value for the index
    }
}

Example

Here's an example of a subscript for a custom type Person that allows us to access a person's name.

struct Person {
   var names = [String]()
   subscript(index: Int) -> String {
      get {
         return names[index]
      }
      set(newValue) {
         names[index] = newValue
      }
   }
}
var person = Person()
person.names = ["John", "Jane", "Mark"]
print(person[0]) // Output: John
person[0] = "Michael"
print(person[0]) // Output: Michael

Output

The output in the above example code will be "John" and "Michael" respectively.

Explanation

In the above example, we have created a Person struct with an array of names. We have defined a subscript for the Person struct that accepts an integer index and returns a string value. In the getter block of the subscript, we return the name corresponding to the given index. In the setter block of the subscript, we assign the passed value to the name corresponding to the given index.

We have created an instance of the Person struct and set the names property. We have accessed the first name using the subscript and printed it to the console. We have then updated the first name using the subscript and printed it again to show that the value has been updated.

Use

Subscripts in Swift are useful for adding custom index notation to your own types. They can be used to simplify the access of elements in a collection or sequence by providing a familiar syntax.

Important Points

  • Subscripts allow us to access elements of a collection, list, or sequence using custom index notation
  • Subscripts are defined using the subscript keyword followed by input and output parameter types
  • Subscripts can have either a getter, a setter, or both
  • Getters are used to retrieve a value from a subscript
  • Setters are used to set a value in a subscript
  • Subscripts can be used to simplify the access of elements in a collection or sequence

Summary

Subscripts in Swift are a powerful feature that allow us to define custom index notation for our own types. They provide a simple and familiar syntax for accessing elements of a collection, list, or sequence. With subscripts, we can create shortcuts that simplify access to complex data structures, making our code more readable and maintainable.

MethodsDeinitialization
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