Swift 2021 _ Tutorialpoint Flashcards
Define Swift 4?
Apple programming Language - designed for iOS and OSX development
Most recent API compatible?
iOS 6
OSX 10.8
Using Swift, is actually fantastic at?
Developing iOS and OSX developments
Using Swift, provides seamless access?
Existing Cocoa frameworks
Using Swift, unifies what?
Procedural and Object-oriented parts of the lanuage
Is a separate library required for certain functionalities?
NOPE!
Swift 4 comes with X that helps programmers to write and execute code?
Playground!
Getting Started
- install XCode
- open it
- select ‘Get started with a playground’
Swift ‘Hello World’ - Playgound
import UIKit var str = "Hello, playground"
Swift ‘Hello World’ - OSX
import Cocoa var str = "Hello, playground"
‘Hello World’s difference??
import UIKit
VS
import Cocoa
Semicolon - single line - required?
Nope
but optional
Semicolon - for multi lined?
Required!
Special Characters not allowed as Identifiers?
@, $, %
Is Swift case sensitive?
YEs
How to use a reserved word as an identifier?
class
Use ( ` ) - backtick
Whitespaces?
Totally ignored!
Type of Whitespaces?
blanks, tabs, newline characters, AND comments
Correct use of spacing?
int fruit = apples +oranges //is a wrong statement
int fruit = apples + oranges //is a Correct statement
Printing in Swift
3 properties:
- Items
- Separator
- Terminator
print(‘hello world”)
Type Aliases
typealias newname = type
eg
typealias Feet = Int
Type Safety means?
if part of your code expects a String you cannot pass it an ‘int’ by mistake
Cannot assign error?
main.swift:2:8: error: cannot assign value of type ‘String’ to type ‘Int’
varA = “This is hello”
Type Annotations are spelled out:
var variableName: =
Eg of Printing Variables
var varA = "Godzilla" var varB = 1000.00
print(“Value of (varA) is more than (varB) millions”)
What’s special about Optional types?
They are a type on their own.
Values of Optionals?
-None
-Some(T)
T - is an associated value of the data type available
Optional - types
To make values ‘nil’
Tuples are?
Used to group multiple values in a single compound Value
Tuple types
Can be any type
Tuple example
var TupleName = (Value1, value2,… any number of values)
Tuple declaration
var error501 = (501, “Not implemented”)
Tuple reference index(es)
print(“The code is(error501.0)”)
print(“The definition of error is(error501.1)”)
What kind of data type can be made constant?
Any and all
Logical Operators
&&( A && B)
|| (A || B)
! (A&&B)
Ternary
Exp1 ? Exp2 : Exp3;
Finding String length?
var varA = “Hello, Swift 4!”
print( “(varA), length is ((varA.count))” )
How to iterate over string using loops?
for chars in “ThisString” {
print(chars, terminator: “ “)
}
output: T h i s S t r i n g
String: isEmpty( )
A Boolean value that determines whether a string is empty or not.
String: hasPrefix(prefix: String)
Function to check whether a given parameter string exists as a prefix of the string or not.
String:hasSuffix(suffix: String)
Function to check whether a given parameter string exists as a suffix of the string or not.
String: toInt()
Function to convert numeric String value into Integer.
String: count()
Global function to count the number of Characters in a string.
String: utf8
Property return a UTF-8 representation of a string.
String: utf16
Property to return a UTF-16 representation of a string.
String: unicodeScalars
Property to return a Unicode Scalar representation of a string.
String: +
Operator to concatenate two strings, or a string and a character, or two characters.
String: +=
Operator to append a string or character to an existing string.
String: ++
Operator to append a string or character to an existing string.
String: ==
Operator to determine the equality of two strings.
String:
Operator to perform a lexicographical comparison to determine whether one string evaluates as less than another.
String: startIndex
To get the value at starting index of string.
String: endIndex
To get the value at ending index of string.
String: Indecies
To access the indeces one by one. i.e all the characters of string one by one.
String: insert(“Value”, at: position)
To insert a value at a position.
String:
remove(at: position)
removeSubrange(range)
to remove a value at a position, or to remove a range of values from string.
String: reversed( )
returns the reverse of a string
Define Char
in Swift it’s a single character String literal
For-in loop example
for ch in “Hello” {
print(ch)
}
How to concatenate Strings?
var varA:String = “Hello “
let varB:Character = “G”
varA.append( varB )
print(“Value of varC = (varA)”)
How strict is Swift’s checking a wrong type into an array?
Very strict! - Not all allowed, even by mistake
How to make an Array?
var someArray = [SomeType]{ }
How to Access an Array?
var someVar = someArray[index]
How to add to existing Array?
array.append( )
How to modify an Element at index?
someInt[2] = 44 //resets
How to enumerate( ) an array with for-in loop?
var someStrs = String
someStrs.append(“Apple”)
someStrs.append(“Amazon”)
someStrs += [“Google”]
for (index, item) in someStrs.enumerated() {
print(“Value at index = (index) is (item)”)
How to add 2 Arrays?
var intsA = [Int](count:2, repeatedValue: 2) var intsB = [Int](count:3, repeatedValue: 1)
var intsC = intsA + intsB
for item in intsC {
print(item)
}
Define ‘sets’?
Swift 4 sets are used to store distinct values of same types but they don’t have definite ordering as arrays have.
Do sets allow for same variables?
NOPE, only distinct
How to create a ‘set’?
var someSet = Set() //Character can be replaced by data type of set.
Sets: count
someSet.count // prints the number of elements
Sets: insert(‘c’)
someSet.insert(“c”) // adds the element to Set.
Sets: isEmpty
someSet.isEmpty // returns true or false depending on the set Elements.
Sets: remove(‘c’)
someSet.remove(“c”) // removes a element , removeAll() can be used to remove all elements
Sets: contains(‘c’)
someSet.contains(“c”) // to check if set contains this value.
Sets: Iterate - no order
for items in someSet {
print(someSet)
}
Sets: Iterate - ordered
for items in someSet.sorted() {
print(someSet)
}
Swift - define dicitionaries
dictionaries are used to store unordered lists of values of the same type.
How are ‘dictionaries’ different than ‘array’?
Unlike items in an array, items in a dictionary do not have a specified order. You can use a dictionary when you need to look up values based on their identifiers
Basic ‘dictionary’ syntax?
var someDict = KeyType: ValueType
Simple ‘dictionary’ example?
var someDict = Int: String
Dictionary: Sequence Based Initialization
Swift 4 allows you to create Dictionary from arrays (Key-Value Pairs.)
Dictionary: Filtering
Swift 4 allows you to filter values from a dictionary.
Dictionary: Dictionary Grouping
Swift 4 allows you to create grouping of Dictionary values.
Dictionary: Accessing Dictionaries
You can retrieve a value from a dictionary by using subscript syntax, passing the key of the value you want to retrieve within square brackets immediately after the name of the dictionary
Dictionary: Accessing Dictionary - how to
var someVar = someDict[key]
Dictionaries: Modifying Dictionaries
You can use updateValue(forKey:) method to add an existing value to a given key of the dictionary. This method returns an optional value of the dictionary’s value type.
Dictionaries: Modifying Dictionaries - how to
updateValue(forKey:)
method to add an existing value to a given key of the dictionary.
Dictionaries: Remove Key-Value Pairs
method to remove a key-value pair from a dictionary.
Dictionary: for-in loop
Used to loop over elements used in a dictionary
Dictionary: count property
Int of the number of items in a ‘dictionary’
Dictionary: Empy
var someDict3:[Int:String] = Int:String
Function syntax?
func funcname(Parameters) -> returntype {
Function Declaration
tells the compiler about a function’s name, return type, and parameters.
Function Definition
It provides the actual body of the function.
Swift 4: Functions
Defined by ‘func’ keyword
Function Parameter is what?
Function is called by name and passes input values (knows as arguments)
A Function return is waht?
Values passed back from the ‘output’ of the function
Function Syntax?
func funcname(Parameters) -> returntype {
}
Function: return example
func student(name: String) -> String {
return name
}
print(student(name: “First Program”))
print(student(name: “About Functions”))
Output:
First Program
About Functions
Calling Function: Example
func display(no1: Int) -> Int {
let a = no1
return a
}
print(display(no1: 100))
print(display(no1: 200))
Output:
100
200
Function Without Parameter: Syntax
func funcname() -> datatype {
return datatype
}Function Without Parameter: Example
func votersname() -> String {
return "Alice"
}
print(votersname())
Output
Alex
Functions with Return Values
func ls(array: [Int]) -> (large: Int, small: Int) {
var lar = array[0]
var sma = array[0]
for i in array[1.. lar {
lar = i
}
}
return (lar, sma)
}
let num = ls(array: [40,12,-5,78,98])
print("Largest number is: \(num.large) and smallest number is: \(num.small)")
Output
Largest number is: 98 and smallest number is: -5
Functions without Return Values
func sum(a: Int, b: Int) {
let a = a + b
let b = a - b
print(a, b)
}
sum(a: 20, b: 10)
sum(a: 40, b: 10)
sum(a: 24, b: 6)
Output:
30 20
50 40
30 24
Local parameter names are
accessed inside the function alone
External Parameter Names
allow us to name a function parameters to make their purpose more clear
Variadic Parameters
When we want to define function with multiple number of arguments, then we can declare the members as ‘variadic’ parameters. Parameters can be specified as variadic by (···) after the parameter name.
Variadic Parameters: example
func vari(members: N...){
for i in members {
print(i)
}
}
vari(members: 4,3,5)
vari(members: 4.5, 3.1, 5.6)
vari(members: “Swift 4”, “Enumerations”, “Closures”)
Output: 4 3 5 4.5 3.1 5.6 Swift 4 Enumerations Closures
let VS var
that ‘let’ keyword is used to declare constant parameters and variable parameters is defined with ‘var’ keyword
inout’ keyword
declared to retain the member values
functionality to retain the parameter values even though its values are modified after the function call. At the beginning of the function parameter definition
‘&’ before a variable name
refers that we are passing the argument to the in-out parameter.
in-out Example
func temp(a1: inout Int, b1: inout Int) {
let t = a1
a1 = b1
b1 = t
}
var no = 2
var co = 10
temp(a1: &no, b1: &co)
print("Swapped values are \(no), \(co)")
Output:
Swapped values are 10, 2
Void functions do what?
Functions may also have void data types and such functions won’t return anything.
Call we call a function as a parameter?
Yest, we can also pass the function itself as parameter types to another function.
Generic syntax to define closure?
{
(parameters) −> return type in
statements
}
Single Expression Implicit Returns
To return a Single expression statement in expression closures ‘return’ keyword is omitted in its declaration part.
Known Type Closures
Consider the addition of two numbers. We know that addition will return the integer datatype.
Declaring Shorthand Argument Names as Closures
Swift 4 automatically provides shorthand argument names to inline closures, which can be used to refer to the values of the closure’s arguments by the names $0, $1, $2, and so on.
Closures as Operator Functions
Swift 4 provides an easy way to access the members by just providing operator functions as closures. In the previous examples keyword ‘Bool’ is used to return either ‘true’ when the strings are equal otherwise it returns ‘false’.
Closures as Trailers
Passing the function’s final argument to a closure expression is declared with the help of ‘Trailing Closures’.
A nested function captures −
- Outer function arguments.
- Capture constants and variables defined within the Outer function.
Enumeration Types - example
For example, the four suits in a deck of playing cards may be four enumerators named Club, Diamond, Heart, and Spade, belonging to an enumerated type named suit. If a variable V is declared having suit as its data type, one can assign any of those four values to it.
Enumeration in Swift 4 also resembles the structure of C and Objective C.
- It is declared in a class and its values are accessed through the instance of that class.
- Initial member value is defined using enum intializers.
- Its functionality is also extended by ensuring standard protocol functionality.
Enum Example!
enum names {
case Swift
case Closures
}
var lang = names.Closures lang = .Closures
switch lang {
case .Swift:
print("Welcome to Swift")
case .Closures:
print("Welcome to Closures")
default:
print("Introduction")
}
Associated Values
- Different Datatypes
- Ex: enum {10,0.8,”Hello”}
- Values are created based on constant or variable
- Varies when declared each time
Raw Values
- Same Datatypes
- Ex: enum {10,35,50}
- Prepopulated Values
- Value for member is same
Example of Structure?
In Structure the variable values are copied and passed in subsequent codes by returning a copy of the old values so that the values cannot be altered.
