A type with a customized textual representation.

    protocol CustomStringConvertible


    Types that conform to the CustomStringConvertible protocol can provide their own representation to be used when converting an instance to a string. The String(describing:) initializer is the preferred way to convert an instance of any type to a string. If the passed instance conforms to CustomStringConvertible, the String(describing:) initializer and the print(_:) function use the instance’s custom description property.

    Accessing a type’s description property directly or using CustomStringConvertible as a generic constraint is discouraged.

    Conforming to the CustomStringConvertible Protocol

    Add CustomStringConvertible conformance to your custom types by defining a description property.

    For example, this custom Point struct uses the default representation supplied by the standard library:

    struct Point {
        let x: Int, y: Int
    let p = Point(x: 21, y: 30)
    // Prints "Point(x: 21, y: 30)"

    After implementing the description property and declaring CustomStringConvertible conformance, the Point type provides its own custom representation.

    extension Point: CustomStringConvertible {
        var description: String {
            return "(\(x), \(y))"
    // Prints "(21, 30)"


    Instance Properties


    Instance Properties