Swift - Control Flows

Control Flow
This is Part 3 of our Swift tutorial series. In this article, we are going to discuss about if and switch to make conditional execution and for, for-in, while and repeat-while to make loops.

IF

An If condition must contain a Boolean expression.
let inviteAllowed = true
if inviteAllowed {
print("All are welcome")
}
Swift allows developers to use let command work with If statement.
let guestName : String? = "Host"
if let guest = guestName {
print("Welcome,  \(guest)")
}
If guestName is set to nil, the if condition would be skipped

IF-ELSE

This is an extended version of If statement. When the condition is success, executes a set of command.
When the condition fails, execute another set of command.
let inviteAllowed = true
if inviteAllowed {
print("All are welcome")
}
else {
print("Invite Only")
}

SWITCH

Switch support all kind of data and operators in swift.
let favouriteColor = "light blue"
let statemnt = "My favourite colour is"
switch (favouriteColor) {
case "red":
print("\(statemnt) red")
case "blue":
print("\(statemnt) blue")
case let colour where colour.hasSuffix("blue"):
print ("\(statemnt) light blue")
default:
print("I like all colours")
}

FOR

A traditional for loop statement in all languages has
-Variable initialisation
-Check for condition
-Increment or decrement the variable
In swift, the traditional statement can be written in simpler format
for var count in 0..10 {
print (count)
}
0..10 - count values would be 0-9. 10 in not included.
to include 10, use 3 dots.
0...10 - count values would be 0-10

WHILE

Executes a set of commands till a condition is met
var n = 2
while n < 50 {
 n = n*2
}

Comments

Post a Comment

Popular posts from this blog

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)...
Read more

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