Tutorial by Examples: r

The accessibility frame is used by VoiceOver for hit testing touches, drawing the VoiceOver cursor, and calculating where in the focused element to simulate a tap when the user double-taps the screen. Note that the frame is in screen coordinates! myElement.accessibilityFrame = frameInScreenCoordina...

VoiceOver works great most of the time, breezily reading aloud screens full of content and intuitively following the user. Alas, no general solution is perfect. Sometimes only you, the app developer, know where VoiceOver should be focused for an optimal user experience. Fortunately, VoiceOver listen...

VoiceOver navigates from top-left to bottom-right, irrespective of the view hierarchy. This is usually how content is arranged in left-to-right languages since sighted individuals tend to scan the screen in an “F-shaped pattern”. VoiceOver users will expect to navigate the same way as typical users....

VoiceOver can navigate many apps on iOS because most UIKit classes implement UIAccessibilityProtocol. Features that don’t represent onscreen elements using UIView, including apps that leverage Core Graphics or Metal to perform drawing, must describe these elements for accessibility. As of iOS 8.0, t...

1.8 You can remove a submodule (e.g. the_submodule) by calling: $ git submodule deinit the_submodule $ git rm the_submodule git submodule deinit the_submodule deletes the_submodules' entry from .git/config. This excludes the_submodule from git submodule update, git submodule sync and git ...

List Comprehensions can use nested for loops. You can code any number of nested for loops within a list comprehension, and each for loop may have an optional associated if test. When doing so, the order of the for constructs is the same order as when writing a series of nested for statements. The ge...

Closures are often used for asynchronous tasks, for example when fetching data from a website. 3.0 func getData(urlString: String, callback: (result: NSData?) -> Void) { // Turn the URL string into an NSURLRequest. guard let url = NSURL(string: urlString) else { return } let re...

It is possible to force the type parameters of a generic class to implement a protocol, for example, Equatable class MyGenericClass<Type: Equatable>{ var value: Type init(value: Type){ self.value = value } func getValue() -> Type{ return self....

Scollector has built in support for using cAdvisor to generate container.* metrics in Bosun for each Docker container on a host. To get started you will need to start a new container on each docker host: docker run --name cadvisor --restart=always -d -p 8080:8080 google/cadvisor And then from an...

Example init script for scollector: #!/bin/bash # # scollector Startup script for scollector. # # chkconfig: 2345 90 60 # description: scollector is a replacement for OpenTSDB's TCollector \ # and can be used to send metrics to a Bosun server # Source function library. . /etc/init....

Here is an init.d script for Bosun that includes setting Environmental Variables that can be used to hide secrets from the raw config. It uses http://software.clapper.org/daemonize/ to run the program as a daemon. #!/bin/sh # # /etc/rc.d/init.d/bosun # bosun # # chkconfig: - 98 02 # descripti...

#Create Scollector unit file at /etc/systemd/system/scollector.service [Unit] Description=Scollector Service After=network.target [Service] Type=simple User=root ExecStart=/opt/scollector/scollector -h mybosunserver.example.com Restart=on-abort [Install] WantedBy=multi-user.target #...

TSDBRelay can be used to forward metrics to an OpenTSDB instance, send to Bosun for indexing, and relay to another opentsdb compatible instance for backup/DR/HA. It also has options to denormalize metrics with high tag cardinality or create redis/ledis backed external counters. #Create tsdbrelay un...

Chef Scollector Cookbook: https://github.com/alexmbird/chef-scollector Chef Bosun Cookbook: https://github.com/ptqa/chef-bosun Puppet scollector module: https://github.com/axibase/axibase-puppet-modules Bosun Ansible/Vagrant example: https://github.com/gnosek/bosun-deploy

docker ps --format 'table {{.ID}}\t{{.Names}}\t{{.Status}}'

docker ps --filter name=myapp_1

This example assumes Ruby is installed. Place the following in a file named hello.rb: puts 'Hello World' From the command line, type the following command to execute the Ruby code from the source file: $ ruby hello.rb This should output: Hello World The output will be immediately di...

git bisect allows you to find which commit introduced a bug using a binary search. Start by bisecting a session by providing two commit references: a good commit before the bug, and a bad commit after the bug. Generally, the bad commit is HEAD. # start the git bisect session $ git bisect start ...

To explicitly declare variables in VBA, use the Dim statement, followed by the variable name and type. If a variable is used without being declared, or if no type is specified, it will be assigned the type Variant. Use the Option Explicit statement on first line of a module to force all variables t...

public class CustomFormat : IFormatProvider, ICustomFormatter { public string Format(string format, object arg, IFormatProvider formatProvider) { if (!this.Equals(formatProvider)) { return null; } if (format == "Reverse") ...