Igor Savelev leonspok

How to get the current selected Xcode and list installed

Current Selected Xcode

`xcode-select`

This is the most common way to get the path to the selected instance:

xcrun xcode-select --print-path

Multiple Xcode versions or Why `xcrun` is your friend

The story

I recently spent a few hours helping a friend of mine investigate a weird issue in their Continuous Development infrastructure. Builds were failing with different fatal errors mostly related to SDK paths and .platform directory locations. At first sight, it was clear that something is wrong with the current selected Xcode, but all our initial attempts to catch the problem failed.

In the end, we isolated the problem; one of the tools they use changes PATH silently for the environment to simplify access to Xcode tools. Due to their internal logic, the CD pipeline changes a current selected Xcode a few times on the way within the same script. In some cases, the pipeline ended with xcodebuild in the environment's PATH that does not reflect the expected version after the xcode-select --switch command.

How? Pretty easy, actually. A simplified sequence looked like this:

Xcode invocation tool - xed

xed is a command-line tool that launches the Xcode application and opens the given documents (xcodeproj, xcworkspace, etc.), or opens a new document, optionally with the contents of standard input.

If you work from the command line, this tool is a better option than open (which can open Xcode projects as well). Why?

xed knows about the current selected Xcode version (open behaves unpredictably if you have multiple Xcode installed)
You can use it open all files from a specific commit (with a little help explained below). It is useful on code-reviews or when you want to explore significant changes in the repository
You can use it as a "quick open" helper. Helps with monorepo phenomena, when you have hundreds of projects in the repository (I will show you an example below)

Skip verifying disk images

defaults write com.apple.frameworks.diskimages skip-verify true

Always hide the Desktop

defaults write com.apple.finder CreateDesktop false; killall Finder

Make terminal logins fast

touch ~/.hushlogin

Disable most animations

Safest way to clean up boot partition - Ubuntu 14.04LTS-x64, Ubuntu 16.04LTS-x64

Reference

Case I: if /boot is not 100% full and apt is working

1. Check the current kernel version

$ uname -r

OpenCV Video Writer on Mac OS X

Fourcc tests:

x : not worked
o: worked (able to open in quicktime but need conversion)
oo: worked well (preview worked but wrong aspect ratio)
ooo: worked very well (preview worked, and aspect ratio’s right)

(Codecs are extracted from https://web.archive.org/web/20120722124832/http://opencv.willowgarage.com/wiki/QuickTimeCodecs )

[Isolating Differences Between Files][paper]

Advantage over Other Algorithms

The diff output is more specific:

[I]f a whole block of text is moved, then all of it, rather than just the beginning and end, is detected as changed.

>The algorithm described here avoids these difficulties. It detects differences that correspond very closely to our intuitive notion of difference.

	// Excerpt from https://github.com/krzyzanowskim/CoreTextWorkshop
	// Licence BSD-2 clause
	// Marcin Krzyzanowski [email protected]

	func getSizeThatFits(_ attributedString: NSAttributedString, maxWidth: CGFloat) -> CGSize {
	let framesetter = CTFramesetterCreateWithAttributedString(attributedString)
	let rectPath = CGRect(origin: .zero, size: CGSize(width: maxWidth, height: 50000))

	let ctFrame = CTFramesetterCreateFrame(framesetter, CFRange(), CGPath(rect: rectPath, transform: nil), nil)

	UIImage* image = [UIImage imageNamed:@"inspiration-2.jpg"]; // image stored in app's resources

	// stage an image
	[FBRequestConnection startForUploadStagingResourceWithImage:image
	completionHandler:^(FBRequestConnection connection, id result, NSError error) {
	if(error) {
	NSLog(@"Error staging resource.\n%@", error);

	int code = [[[[[error userInfo] objectForKey:@"com.facebook.sdk:ParsedJSONResponseKey"] objectForKey:@"body"] objectForKey:@"error"] objectForKey:@"code"];
	if(code == 2500) {