Tutorial by Examples: io

If you want to lock the screen orientation change of any screen (activity) of your android application you just need to set the android:screenOrientation property of an <activity> within the AndroidManifest.xml: <activity android:name="com.techblogon.screenorientationexample.Main...

If your application doesn't need to update resources during a specific configuration change and you have a performance limitation that requires you to avoid the activity restart, then you can declare that your activity handles the configuration change itself, which prevents the system from restartin...

Demonstrate how to embed a lua interpreter in C code, expose a C-defined function to Lua script, evaluate a Lua script, call a C-defined function from Lua, and call a Lua-defined function from C (the host). In this example, we want the mood to be set by a Lua script. Here is mood.lua: -- Get versi...

To setup a WebRTC-based communication system, you need three main components: A WebRTC signaling server To establish a WebRTC connections, peers need to contact a signaling server, which then provides the address information the peers require to set up a peer-to-peer connection. Signaling serv...

Suppose you have multiple threads running. Each thread is doing one task. You want to get notified either on the mainThread OR another thread, when all the task-threads are completed. The simplest solution to such a problem is a DispatchGroup. When using a DispatchGroup, for each request, you ente...

Validation attributes can be used to easily configure model validation. public class MyModel { public int id { get; set; } //sets the FirstName to be required, and no longer than 100 characters [Required] [StringLength(100)] public string FirstName { get; set; } } Th...

CALayer property animations are enabled by default. When this is undesirable, they can be disabled as follows. Swift CATransaction.begin() CATransaction.setDisableActions(true) // change layer properties that you don't want to animate CATransaction.commit() Objective-C [CATransaction be...

You can test that a function throws an exception with the built-in unittest through two different methods. Using a context manager def division_function(dividend, divisor): return dividend / divisor class MyTestCase(unittest.TestCase): def test_using_context_manager(self): ...

In an iOS app, your user interface can take on one of a few different general shapes and sizes. These are defined using size classes, which are available through a view or view controller's trait collection. Apple defines two size classes: regular and compact. Each of these size classes are availab...

Making an app adaptive – that is, responding to size class changes by changing your layout – often involves lots of help from the Auto Layout system. One of the primary ways apps become adaptive is by updating the active Auto Layout constraints when a view's size class changes. For example, conside...

A key piece of adaptivity in a modern iOS app is supporting multitasking on iPad. By default, apps created in Xcode 7 and newer will be configured to support multitasking: they'll have a LaunchScreen.storyboard file that uses Auto Layout. The easiest way for existing apps to opt in to multitasking ...

There are a few ways to use functions. Calling a function with an assignment statement DECLARE x NUMBER := functionName(); --functions can be called in declaration section BEGIN x := functionName(); END; Calling a function in IF statement IF functionName() = 100 THEN Null; EN...

A bibtex catalogue cna easily be included with the YAML option bibliography:. A certain style for the bibliography can be added with biblio-style:. The references are added at the end of the document. --- title: "Including Bibliography" author: "John Doe" output: pdf_documen...

A simple POST request with authentication data is demonstrated below, note that the username and password field will vary depending on the website: final String USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36"; ...

Most websites require a much more complicated process than the one demonstrated above. Common steps for logging into a website are: Get the unique cookie from the initial login form. Inspect the login form to see what the destination url is for the authentication request Parse the login form t...

The built-in werkzeug server certainly is not suitable for running production servers. The most obvious reason is the fact that the werkzeug server is single-threaded and thus can only handle one request at a time. Because of this we want to use the uWSGI Server to serve our application instead. In...

The example in Visitor Pattern provides a compelling use-case for CRTP: struct IShape { virtual ~IShape() = default; virtual void accept(IShapeVisitor&) const = 0; }; struct Circle : IShape { // ... // Each shape has to implement this method the same way ...

In Object Oriented Programming a common task is to compose objects (values). In Functional Programming it is as common task to compose values as well as functions. We are used to compose values from our experience of other programming languages using operators like +, -, *, / and so on. Value co...

Arrays Dim names = {"Foo", "Bar"} ' Inferred as String() Dim numbers = {1, 5, 42} ' Inferred as Integer() Containers (List(Of T), Dictionary(Of TKey, TValue), etc.) Dim names As New List(Of String) From { "Foo", "Bar" '... ...

You might expect a Python dictionary to be sorted by keys like, for example, a C++ std::map, but this is not the case: myDict = {'first': 1, 'second': 2, 'third': 3} print(myDict) # Out: {'first': 1, 'second': 2, 'third': 3} print([k for k in myDict]) # Out: ['second', 'third', 'first'] Py...