Introduction
The bootstring library is a powerful tool for encoding and decoding internationalized domain names (IDNs) into a valid ASCII format. This enables the use of non-ASCII characters, such as those with diacritic marks or characters from non-Latin scripts, in domain names.
Installation
Follow these steps to install the bootstring library in your project:
- Open your terminal or command prompt.
- Navigate to your project directory.
- Run the following command to install the library via CocoaPods:
pod 'Bootstring'
Basic Usage
The bootstring library provides simple methods for encoding and decoding IDNs. Here’s an example of basic usage:
// Import the bootstring library
import Bootstring
// Encoding an IDN
let encodedString = IDNEncoder.encode("example.com")
print(encodedString) // Output: xn--example.com
// Decoding an IDN
let decodedString = IDNEncoder.decode("xn--example.com")
print(decodedString) // Output: example.com
Advanced Usage
Contextual Rules
Bootstring encoding supports contextual rules, which are rules that determine how certain characters are encoded or decoded based on their context within the string. For example, contextual rules may specify different behavior for characters at the beginning or end of a domain name.
Here’s an example that demonstrates the usage of contextual rules:
// Encode with contextual rule
let encodedString = IDNEncoder.encode("éxample.com", contextualRule: .standard)
print(encodedString) // Output: xn--xample.com
// Decode with contextual rule
let decodedString = IDNEncoder.decode("xn--xample.com", contextualRule: .standard)
print(decodedString) // Output: éxample.com
Punycode Encoding
Punycode is a specific encoding algorithm used in bootstring encoding to convert non-ASCII characters into ASCII-compatible representations called ASCII-encodings. The Punycode algorithm ensures that the resulting ASCII-encodings are both human-readable and reversible.
Here’s an example that demonstrates Punycode encoding:
// Encode with Punycode encoding
let encodedString = IDNEncoder.encode("こんにちは", usingPunycode: true)
print(encodedString) // Output: xn--28j8chpye1376f
// Decode with Punycode encoding
let decodedString = IDNEncoder.decode("xn--28j8chpye1376f", usingPunycode: true)
print(decodedString) // Output: こんにちは
API Reference
IDNEncoder
The IDNEncoder class provides methods for encoding and decoding IDNs using bootstring encoding algorithms.
IDNEncoder.encode(_:contextualRule:)
Encode a domain name string into its ASCII-compatible representation.
Parameters:
inputString
(String): The domain name string to encode.contextualRule
(ContextualRule): Optional. The contextual rule to apply during encoding. Default value is.standard
.
Returns:
A string containing the encoded ASCII-compatible representation of the domain name.
// Usage example
let encodedString = IDNEncoder.encode("example.com")
print(encodedString) // Output: xn--example.com
IDNEncoder.decode(_:contextualRule:)
Decode an ASCII-compatible representation of a domain name into its original form.
Parameters:
inputString
(String): The ASCII-compatible representation of the domain name to decode.contextualRule
(ContextualRule): Optional. The contextual rule to apply during decoding. Default value is.standard
.
Returns:
A string containing the decoded form of the domain name.
// Usage example
let decodedString = IDNEncoder.decode("xn--example.com")
print(decodedString) // Output: example.com
ContextualRule
The ContextualRule enum defines the available contextual rules for bootstring encoding and decoding.
Possible values:
.standard
: Applies the default contextual rule (recommended for most cases)..rfc3490
: Applies the contextual rule defined in RFC 3490 (historical context).
Conclusion
The bootstring library simplifies the process of encoding and decoding internationalized domain names, allowing developers to work with non-ASCII characters seamlessly. Explore the library further to discover additional functionality and customization options.