Swift - Strings

String
To declare a string, use let or var keyword.
var greeting = "Hello"   // Mutable string
let name = “Alice” // Immutable string
let keyword creates an immutable string. var creates a mutable string.
To modify a string later in code, use var keyword. let will throw error.
Swift provides a list of common methods extending String class. These methods will perform various operations with strings. Let’s have a look at few of those commonly used methods.

To check the variable is String type

let stringObject = "String here"
if stringObject is String {
print ("Yes") // Yes
}

To check if two strings are equal
let greet1 = "Hello guest"
let greet2 = "Hello world"
if greet1 == greet2 {
print ("same greeting")
}
else {
print ("different greetings")
}

To capitalise all the words
var greeting = "hello guest"
print (greeting.capitalizedString) // HELLO GUEST

To append a string
greeting += "Guest"
print (greeting) // Hello Guest

To check whether a string has particular character, use regular expression
let greeting = "Cherry blue"
if greeting.rangeOfString("r+", options: .RegularExpressionSearch) != nil {
print ("Found it") // Found it
}

To check a string contains another string
let greeting = "berry blue"
if greeting.rangeOfString("blue") != nil {
print ("yes") // yes
}

To check a string has a particular prefix


 let greeting = "Super man"
if greeting.hasPrefix ("Sup") {
print ("Yes, Prefix found")
}
else {
print ("Not found")
}

To check a string has a particular suffix
let greeting = "Super man"
if greeting.hasSuffix ("man") {
print ("Yes, Suffix found")
}
else {
print ("Not found")
}

To check a string is empty
let sauce = "tomato"
if sauce.isEmpty {
print ("Empty string")
}

To generate a unique string
let uniqueString = NSUUID().UUIDString
print (uniqueString) // generated unique string

To get a substring from a range of string
let lengthy = "this is a lengthy string"
let small = lengthy[lengthy.startIndex.advanceBy(7)..
print (small) // a lengthy string

To get the string characters count
let lengthy = "this is a lengthy string"

print (lengthy.characters.count) // 24

To replace an occurrence of a string
let greeting = "Good Morning"
let greet = greeting.stringByReplacingOccurrencesOfString("Morning", with: "Evening")
print (greet) // Good Evening

To reverse a string characters
let straight = "Hello"
let reverse = String(straight.characters.reverse())
print (reverse) // olleh


To split a string into many sub string and store them in an array
let greet = "Hello world"
var arrayGreet = greet.componentsSeparatedByString(" ")
print (arrayGreet)

To trim white space in a string
let greet = "Hello world "
var trimmedGreet = greet.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
print (trimmedGreet)

Comments

Post a Comment

Popular posts from this blog

What's new in Swift 4!

Swift 4 Apple has introduced an update to Swift during its WWDC. Lets discuss some of the new features introduced in Swift 4. String In Swift 4, String has been revised to be a collection again. This gives the feature to reverse, sort and count the characters. Multi-Line String As String literals allows you to create a sequence of characters within quotes (“), Swift 4 starting to support multi-line characters. A multi-line string is enclosed within 3 quotes ("””).   A multi-line can also include unescaped double quotes, carriage return and line feeds. To add a line feed, add a empty line to start and end of the multi-line string.  The indentation defines the spacing between the lines. Example, let singleLineString = “I’m a single line string" let multilineString = “"" I’m a  Multi line string. """ Protocol Composition Swift 4 allows developers to combine multiple protocols into a single type using protocol composition. It will be like ...
Read more

Swift - Classes

Classes This is Part 4 of our Swift tutorial series. To create a class in swift, use class keyword. The properties and methods are declared in the same way as constant and variable. class { init () { } } Let's create a class with functions. class mathsClass { func add (a:Int, b:Int) -> Int { return a+b } } let mathsObject = mathsClass() print (mathsObject.add(a:1, b:1)) // 2 Swift classes supports inheritance . We can create a parent class and inherit its properties in the child class. class Student { func studentName () -> String { return "Alice" } } class ReportCard : Student { } let studentCard = ReportCard() print (studentCard.studentName()) // Alice The above example had the student name in function. Let's create a property and store the value. class Student { var name : String init (studentName : String) { name = studentName } } let student = Student(...
Read more