Tutorial by Examples: n

To avoid verbose null checking, the ?. operator has been introduced in the language. The old verbose syntax: If myObject IsNot Nothing AndAlso myObject.Value >= 10 Then Can be now replaced by the concise: If myObject?.Value >= 10 Then The ? operator is particularly powerful when you...

The NameOf operator resolves namespaces, types, variables and member names at compile time and replaces them with the string equivalent. One of the use cases: Sub MySub(variable As String) If variable Is Nothing Then Throw New ArgumentNullException("variable") End Sub The old sy...

This new feature makes the string concatenation more readable. This syntax will be compiled to its equivalent String.Format call. Without string interpolation: String.Format("Hello, {0}", name) With string interpolation: $"Hello, {name}" The two lines are equivalent and ...

Getting current date is very easy. You get NSDate object of current date in just single line as follows: Swift var date = NSDate() Swift 3 var date = Date() Objective-C NSDate *date = [NSDate date];

The number of seconds from the current date and time for the new date. Use a negative value to specify a date before the current date. For doing this we have a method named dateWithTimerIntervalSinceNow(seconds: NSTimeInterval) -> NSDate (Swift) or + (NSDate*)dateWithTimeIntervalSinceNow:(NSTime...

There are 4 methods for comparing dates: Swift isEqualToDate(anotherDate: NSDate) -> Bool earlierDate(anotherDate: NSDate) -> NSDate laterDate(anotherDate: NSDate) -> NSDate compare(anotherDate: NSDate) -> NSComparisonResult Objective-C - (BOOL)isEqualToDate:(NSDate *)anothe...

Get the description of an specific property in an object. var sampleObject = { hello: 'world' }; Object.getOwnPropertyDescriptor(sampleObject, 'hello'); // Object {value: "world", writable: true, enumerable: true, configurable: true}

Swift let alert = UIAlertController(title: "Hello", message: "Welcome to the world of iOS", preferredStyle: UIAlertControllerStyle.alert) let defaultAction = UIAlertAction(title: "OK", style: UIAlertActionS...

Dim array() As Integer = {2, 0, 1, 6} ''Initialize an array of four Integers. Dim strings() As String = {"this", "is", "an", "array"} ''Initialize an array of four Strings. Dim floats() As Single = {56.2, 55.633, 1.2, 5.7743, 22.345} ...

Compare method Either you implement a compare-method for your object: - (NSComparisonResult)compare:(Person *)otherObject { return [self.birthDate compare:otherObject.birthDate]; } NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)]; NSSortDescriptor NSS...

Custom Font Support Applications that want to use custom fonts can now include those fonts in their application bundle and register those fonts with the system by including the UIAppFonts key in their Info.plist file. The value of this key is an array of strings identifying the font files in the ...

We write custom action filters for various reasons. We may have a custom action filter for logging, or for saving data to database before any action execution. We could also have one for fetching data from the database and setting it as the global values of the application. To create a custom actio...

To get the timestamp in seconds Math.floor((new Date().getTime()) / 1000)

With UIAlertController, action sheets like the deprecated UIActionSheet are created with the same API as you use for AlertViews. Simple Action Sheet with two buttons Swift let alertController = UIAlertController(title: "Demo", message: "A demo with two buttons", preferredStyle...

getPreferences(int) returns the preferences saved by Activity's class name as described in the docs : Retrieve a SharedPreferences object for accessing preferences that are private to this activity. This simply calls the underlying getSharedPreferences(String, int) method by passing in this acti...

YourAsyncTask task = new YourAsyncTask(); task.execute(); task.cancel(); This doesn't stop your task if it was in progress, it just sets the cancelled flag which can be checked by checking the return value of isCancelled() (assuming your code is currently running) by doing this: class YourAsyn...

The following is an excerpt from Gradle - What is a non-zero exit value and how do I fix it?, see it for the full discussion. Let's say you are developing an application and you get some Gradle error that appears that generally will look like so. :module:someTask FAILED FAILURE: Build failed with...

To spawn a new process in which you need unbuffered output (e.g. long-running processes which might print output over a period of time rather than printing and exiting immediately), use child_process.spawn(). This method spawns a new process using a given command and an array of arguments. The retu...

Classes can be created as follow: class InputField { int maxLength; String name; } The class can be instantiated using the new keyword after which the field values will be null by default. var field = new InputField(); Field values can then be accessed: // this will trigger the sette...

<p contenteditable>This is an editable paragraph.</p> Upon clicking on the paragraph, the content of it can be edited similar to an input text field. When the contenteditable attribute is not set on an element, the element will inherit it from its parent. So all child text of a conte...