{"id":3021,"date":"2016-06-17T19:27:58","date_gmt":"2016-06-18T01:27:58","guid":{"rendered":"http:\/\/dev.iachieved.it\/iachievedit\/?p=3021"},"modified":"2017-05-02T19:25:49","modified_gmt":"2017-05-03T00:25:49","slug":"swift-3-0-on-raspberry-pi-2-and-3","status":"publish","type":"post","link":"https:\/\/dev.iachieved.it\/iachievedit\/swift-3-0-on-raspberry-pi-2-and-3\/","title":{"rendered":"Swift 3.0 on Raspberry Pi 2 and 3"},"content":{"rendered":"

\"Swift \"Swift \"Swift<\/p>\n

There are a number of people working<\/a> to bring Swift 3.0 to as many ARM-based systems as possible. This article is specifically about getting Swift 3.0 for your Raspberry Pi<\/b> 2 or Raspberry Pi 3 that is running Ubuntu 16 (Xenial Xerus<\/a>). It has not been tested for Raspbian variants (and likely doesn’t work).<\/p>\n

A fair warning:<\/b> support for Swift 3.0 on the Raspberry Pi (and all ARM devices) is still beta. Use it for prototyping and proof-on-concept work rather than building a product with it. Also, if you’re interested in joining the community of folks working on getting Swift 3.0 for ARM devices, come join us on Slack<\/a>!<\/p>\n

Xenial on a Raspberry Pi<\/h2>\n

You might not have even known Xenial for the Raspberry Pi existed; I didn’t! To grab it head over to the Ubuntu Wiki<\/a> and get the distribution for your Pi. You will want to use at least an 8G SD card.<\/p>\n

Install Swift 3.0<\/h2>\n

The team working on Swift for ARM is using Jenkins<\/a> to build the Raspberry Pi binaries natively on a Raspberry Pi 3<\/a>. As in, this is the build machine!<\/p>\n

\"Swift<\/a>
Swift 3.0 Build Machine<\/figcaption><\/figure>\n

For the curious check out the Jenkins build project<\/a>. Quite frankly, I’m amazed that it only took 6 hours to compile Swift.<\/p>\n

Now, on your Raspberry Pi, grab and extract the Swift 3.0 build artifact into a directory and set your PATH<\/code> with something like:<\/p>\n

\ncd $HOME\nwget http:\/\/swift-arm.ddns.net\/job\/Swift-3.0-Pi3-ARM-Incremental\/16\/artifact\/swift-3.0-2016-07-19-RPi23-ubuntu16.04.tar.gz\nmkdir swift-3.0\ncd swift-3.0 && tar -xzf ..\/swift-3.0.tgz\nexport PATH=$HOME\/swift-3.0\/usr\/bin:$PATH\n<\/pre>\n
Note:<\/b> You aren’t tied to putting Swift 3.0 in $HOME<\/code>, I typically use \/opt\/swift\/swift-3.0<\/code>.<\/p>\n
Now, let’s give it a spin!<\/p>\n
Create a file called helloWorld.swift<\/code>:<\/p>\n
\nprint(\"Hello, world!\")\n<\/pre>\n
You can use swift helloWorld.swift<\/code> to execute the file like a script:<\/p>\n
\n# swift helloWorld.swift\nHello, world!\n<\/pre>\n
Or, you can compile the file into an executable with swiftc<\/code> if you have clang<\/code> installed and configured properly<\/i>:<\/p>\n
\n# swiftc helloWorld.swift\n# .\/helloWorld\nHello world!\n<\/pre>\n
If swiftc<\/code> failed with error: link command failed with exit code 127<\/code> there’s a good chance you don’t have clang<\/code> installed and configured properly:<\/p>\n
\nsudo apt-get update\nsudo apt-get install -y libicu-dev\nsudo apt-get install -y clang-3.6\nsudo update-alternatives --install \/usr\/bin\/clang clang \/usr\/bin\/clang-3.6 100\nsudo update-alternatives --install \/usr\/bin\/clang++ clang++ \/usr\/bin\/clang++-3.6 100\n<\/pre>\n
Let’s look at a few other tidbits:<\/p>\n
Importing `Glibc` works!<\/h3>\n
swiftcat.swift<\/code>:<\/p>\n
\nimport Glibc\n\nguard CommandLine.arguments.count == 2 else {\n  print(\"Usage:  swiftcat FILENAME\")\n  exit(-1)\n}\n\nlet filename = CommandLine.arguments[1]\n\nlet BUFSIZE = 1024\nvar pp      = popen(\"cat \" + filename, \"r\")\nvar buf     = [CChar](repeating:0, count:BUFSIZE)\n\nwhile fgets(&buf, Int32(BUFSIZE), pp) != nil {\n  print(String(cString:buf), terminator:\"\")\n}\n\nexit(0)\n<\/pre>\n
Compile (swiftc swiftcat.swift<\/code>) and run (swiftcat<\/code>)!<\/p>\n
Bridging to C routines<\/h3>\n
Linking against compiled object files works!<\/p>\n
escapetext.c<\/code>:<\/p>\n
\n#include \n#include \n#include \nint escapeText(const char* text, char** output) {\n  int rc = -1;\n  CURL* curl = curl_easy_init();\n  if (curl) {\n    char* escaped = curl_easy_escape(curl, text, strlen(text));\n    if (escaped) {\n      *output = (char*)malloc(strlen(escaped) + 1);\n      strcpy(*output, escaped);\n      curl_free(escaped);\n      rc = strlen(*output);\n    }\n  }\n  return rc;\n}\n<\/pre>\n
escapetext.h<\/code>:<\/p>\n
\nint escapeText(const char* text, char** output);\n<\/pre>\n
escapeswift.swift<\/code>:<\/p>\n
\nimport Glibc\n\nguard CommandLine.arguments.count == 2 else {\n  print(\"Usage:  escapeswift STRING\")\n  exit(-1)\n}\n\nlet string = CommandLine.arguments[1]\nvar buffer:UnsafeMutablePointer? = nil\n\nlet rc = escapeText(string, &buffer)\n\nguard rc > 0 else {\n  print(\"Error escaping text\")\n  exit(-1)\n}\n\nif let escaped = buffer {\n  let escapedString = String(cString:escaped)\n  print(\"Escaped text:  \" + escapedString)\n}\n\nexit(0)\n<\/pre>\n
Compile and link everything together:<\/p>\n
\n# clang -c escapetext.c\n# swiftc -c escapeswift.swift -import-objc-header escapetext.h\n# swiftc escapeswift.o escapetext.o -o escapeswift -lcurl\n<\/pre>\n
And run:<\/p>\n
\n# .\/escapeswift \"foo > bar\"\nEscaped text:  foo%20%3E%20bar\n<\/pre>\n
Swift Package Manager<\/h3>\n
Unless you enjoy writing makefiles and build scripts (and trust me, some do), the Swift Package Manager is here to help manage software package dependencies.  We’ll be writing more about the SwiftPM available in Swift 3.0, but are excited to provide a version that works on armv7 devices.  Try this out:<\/p>\n
\n# mkdir finalCountdown && cd finalCountdown\n# swift package init --type executable\nCreating executable package: finalCountdown\nCreating Package.swift\nCreating .gitignore\nCreating Sources\/\nCreating Sources\/main.swift\nCreating Tests\/\n<\/pre>\n
Replace the contents of Sources\/main.swift<\/code> with<\/p>\n
\nimport Foundation\nimport Glibc\nlet thread = Thread(){\n  print(\"Entering thread\")\n  for i in (1...10).reversed() {\n    print(\"\\(i)...\", terminator:\"\")\n    fflush(stdout)\n    sleep(1)\n  }\n  print(\"\\nExiting thread\")\n  print(\"Done\")\n  exit(0)\n}\nthread.start()\nselect(0, nil, nil, nil, nil)\n<\/pre>\n
Now, run swift build<\/code> to build your finalCountdown<\/code> application:<\/p>\n
\n# swift build\nCompile Swift Module 'finalCountdown' (1 sources)\nLinking .build\/debug\/finalCountdown\n# .build\/debug\/finalCountdown\nEntering thread\n10...9...8...7...6...5...4...3...2...1...\nExiting thread\nDone\n<\/pre>\n
moreswift<\/h3>\n
For a random smattering of Swift 3.0 applications that have been run on both x86 and armv7 systems, check out the moreswift swift-3.0 branch<\/a>.<\/p>\n
What Version Is This?<\/h2>\n
The current builds available are not tracking the Swift 3.0 preview builds.  To determine the Git hashes associated with the swift<\/code> binary, type swift --version<\/code>:<\/p>\n
\n# swift --version\nSwift version 3.0-dev (LLVM eb140647a6, Clang a9f2183da4, Swift bb43874ba1)\n<\/pre>\n
You can then, if you so choose go directly to the Swift repository commit with something like https:\/\/github.com\/apple\/swift\/tree\/bb43874ba1<\/a> to see the history beginning with the last commit incorporated into the build.<\/p>\n
Acknowledgements<\/h2>\n
A lot of people have been apart of the effort to bring Swift to Linux ARM devices.  This list is just a few of those individuals.  Please do visit their blogs; there is a wealth of information and learnings therein.<\/p>\n