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Useful information The very beginning of the text field text: let startPosition: UITextPosition = textView.beginningOfDocument The very end of the text field text: let endPosition: UITextPosition = textView.endOfDocument The currently selected range: let selectedRange: UITextRange? = textV...

The example below shows how to add a navigation bar button (called a UIBarButtonItem) in the Interface Builder. Add a Navigation Controller to your Storyboard Select your View Controller and then in the Xcode menu choose Editor > Embed In > Navigation Controller. Alternatively, you could ...

Test methods often need data to be tested with. To test some methods completely you need to provide different data sets for every possible test condition. Of course, you can do it manually using loops, like this: ... public function testSomething() { $data = [...]; foreach($data as $dat...

Below is an example of a pure Xamarin Forms custom control. No custom rendering is being done for this but could easily be implemented, in fact, in my own code, I use this very same control along with a custom renderer for both the Label and Entry. The custom control is a ContentView with a Label, ...

There are a couple of default recognizers available in Xamarin.Forms, one of them is the TapGestureRecognizer. You can add them to virtually any visual element. Have a look at a simple implementation which binds to an Image. Here is how to do it in code. var tappedCommand = new Command(() => {...

In order to make an Image (or any other visual element) zoomable we have to add a PinchGestureRecognizer to it. Here is how to do it in code: var pinchGesture = new PinchGestureRecognizer(); pinchGesture.PinchUpdated += (s, e) => { // Handle the pinch }; image.GestureRecognizers.Add(pi...

When you have a zoomed Image (or other content) you may want to drag around the Image to show all of its content in the zoomed in state. This can be achieved by implementing the PanGestureRecognizer. From code this looks like so: var panGesture = new PanGestureRecognizer(); panGesture.PanUpdated...

EntryPage.xaml: <?xml version="1.0" encoding="utf-8" ?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:vm="clr-namespace:MyAssembly.ViewModel;a...

Redis keys are binary-safe, so literally anything can be used as a key. The only limitations are that they must be less than 512MB. Examples of valid keys: 7 ++++ `~!@#$%^&*()-_=+ user:10134 search/9947372/?query=this%20is%20a%28test%29%20query <div id="div64"> Any othe...

For clarity and maintainability, it is often recommended to develop a system or schema for naming your Redis keys. Here are some examples of common and maintainable systems for naming your keys: user:10134 user:10134:favorites user:10134:friends user:10134:friends-of-friends user:10134 user:...

You can simply use the native map APIs on each platform with Xamarin Forms. All you need is to download the Xamarin.Forms.Maps package from nuget and install it to each project (including the PCL project). Maps Initialization First of all you have to add this code to your platform-specific project...

Using the System.String.Contains you can find out if a particular string exists within a string. The method returns a boolean, true if the string exists else false. string s = "Hello World"; bool stringExists = s.Contains("ello"); //stringExists =true as the string contains t...

The System.String.Trim method can be used to remove all leading and trailing white-space characters from a string: string s = " String with spaces at both ends "; s = s.Trim(); // s = "String with spaces at both ends" In addition: To remove white-space only fro...

Using the System.String.Replace method, you can replace part of a string with another string. string s = "Hello World"; s = s.Replace("World", "Universe"); // s = "Hello Universe" All the occurrences of the search string are replaced: string s = "He...

Use the System.String.Split method to return a string array that contains substrings of the original string, split based on a specified delimiter: string sentence = "One Two Three Four"; string[] stringArray = sentence.Split(' '); foreach (string word in stringArray) { Console.W...

The System.String.Join method allows to concatenate all elements in a string array, using a specified separator between each element: string[] words = {"One", "Two", "Three", "Four"}; string singleString = String.Join(",", words); // singleString =...

String Concatenation can be done by using the System.String.Concat method, or (much easier) using the + operator: string first = "Hello "; string second = "World"; string concat = first + second; // concat = "Hello World" concat = String.Concat(first, second); // ...

Conventional algebraic datatypes are parametric in their type variables. For example, if we define an ADT like data Expr a = IntLit Int | BoolLit Bool | If (Expr Bool) (Expr a) (Expr a) with the hope that this will statically rule out non-well-typed conditionals, this...

In some cases we need to apply functions to a set of ND-arrays. Let's look at this simple example. A(:,:,1) = [1 2; 4 5]; A(:,:,2) = [11 22; 44 55]; B(:,:,1) = [7 8; 1 2]; B(:,:,2) = [77 88; 11 22]; A = ans(:,:,1) = 1 2 4 5 ans(:,:,2) = 11 22 44 55 >&...

Let's look at a sample of logging which you can see in many programs: public class LoggingComplex { private static final Logger logger = Logger.getLogger(LoggingComplex.class.getName()); private int total = 50, orders = 20; private String username = "Bob";...