Checksum
Extends String
, Data
, and URL
adding the ability to easily and efficiently calculate the cryptographic checksum of its associated
contents by adding conformance to the Checksumable
protocol.
Under the hood, Apple's CommonCrypto
framework is used.
Requirements
- iOS 9 / macOS 10.11 / tvOS 9 / watchOS 2
- Xcode 10.2
- Swift 4.0 / 4.2 / 5.0 / 5.1
Documentation
Features
Supported Digests
MD5
, SHA1
, SHA224
, SHA256
, SHA384
, SHA512
Async Processing
Processing and progress monitoring are performed asynchronously on a background dispatch queue. Progress and completion
closures are, by default, called on the .main
dispatch queue. However, a different DispatchQueue
may be specified.
The function signature for async processing is:
checksum(algorithm:chunkSize:queue:progress:completion:)
Sync Processing
In the cases where the payload is fairly small, asynchronous processing may not be required or desirable. For such cases, a synchronous version is provided.
The function signature for sync processing is:
checksum(algorithm:chunkSize:)
Process Local or Remote URLs
Any URLs with schemes file
, http
, or https
may be used as input. However, http
and https
support is currently experimental and has the following requirements:
- The HTTP server must be able to respond to
HEAD
requests in order to determine whether theURL
is reachable. - The HTTP server must be able to serve 206 Partial Content responses.
Batch Processing
Support for processing arrays of Checksumable
items is also included and showcased in the examples below.
Examples
Data
asynchronously
Calculating the checksum of some data.checksum(algorithm: .md5) { result in
switch result {
case .success(let checksum):
// Use checksum
case .failure(let error):
// Unable to obtain checksum
}
}
URL
asynchronously
Calculating the checksum of the content at a given remoteURL.checksum(algorithm: .sha256) { result in
switch result {
case .success(let checksum):
// Use checksum
case .failure(let error):
// Unable to obtain checksum
}
}
URLs
asynchronously
Calculating the checksums of the contents at given [someURL, anotherURL, yetAnotherURL].checksum(algorithm: .md5) { result in
switch result {
case .success(let checksumResults):
// Use results object
for checksumResult in checksumResults {
guard let url = checksumResult.checksumable as? URL else {
fail("Expected checksumable to be of type URL.")
return
}
if let checksum = checksumResult.checksum {
print("Checksum of \(result.checksumable) is \(checksumResult.checksum)")
} else {
print("Unable to obtain checksum for \(checksumResult.checksumable)")
}
}
case .failure(let error):
// Unable to obtain checksums
}
}
String
synchronously
Calculating the checksum of some if let checksum = string.checksum(algorithm: .md5) {
// Use checksum
}
Data
synchronously
Calculating the checksum of some if let checksum = data.checksum(algorithm: .md5) {
// Use checksum
}
URL
synchronously
Calculating the checksum of the content at a given if let checksum = localURL.checksum(algorithm: .md5) {
// Use checksum
}
Progress Reporting
You may monitor progress by passing a ProgressHandler
closure to the progress
argument in
checksum(algorithm:chunkSize:queue:progress:completion:)
.
Example
remoteURL.checksum(algorithm: .sha256, progress: { progress in
// Add your progress handling code here.
print("Fraction completed: \(progress.fractionCompleted)")
}) { result in
/// Result handling ommited.
}
License
Checksum
was written by Ruben Nine (@sonicbee9) and is licensed under the
MIT license. See LICENSE.md.