🐦swift swift grimoire

[fukurou]

 

[fukurou]

randomizer

Int.random(in: 0...5) // includes 0 and 5
Int.random(in: 0..<5) // includes 0

array1.randomElement()! // returns a random element from the array

 

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switch with range

switch x {
case 80...90:
    print("x in range")

case x..<10:
    print("x is small")

case 50:
    print("50")

default:
    print("Have you done something new?")
}

:hmm: ...10 can replace x..<10

 

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Ternary Operator in Swift​

condition ? expression1 : expression2

 

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multi array

2d:
var cinema = [[Int]]()
or
var cinema = Array(repeating: Array(repeating: 0, count: 5), count: 5)

N-dimensional arrays​

var cinemas = [[[Int]]]()
var cinemas = Array(repeating: Array(repeating: Array(repeating: 0, count: 5), count: 5), count: 3)
cinemaRooms[1][2][3] = 1 // the second-floor cinema, the third row, the fourth seat

iteration 3d array :

var floor = 1

for cinema in cinemas {
    print("Floor: \(floor)")
    floor += 1
    for array in cinema {
        for value in array {
            print(value, terminator: " ")
        }
        print(" ")
    }
    print("-----------------")
}

 

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struct

// define a structure
struct Person {

// define two properties
 var name = ""
 var age = 0
}

// create instance of Person
var person1 = Person()

// access properties and assign new values
person1.age = 21
person1.name = "Rick"

print("Name: \(person1.name) and Age: \( person1.age) ")

 

[fukurou]

Struct vs. Class in Swift​

struct is pretty much a constant you can modify (with fields)
1 it gets passes as a value not as a reference
2 init is optional for struct
3 struct does have inheritance

 

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mutating struct properties :

struct Person {

// define two properties
 var name = ""
 var age = 0
    mutating func birthday(){
        self.age += 1
    }
}

// create instance of Person
var person1 = Person()
person1.birthday()
print(person1.age)

 

[fukurou]

round decimal to 2 decimal places :

let temp = String(format: "%.2f", value)

 

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type conversion

let temp = String(format: "%0.2f", sender.value)

 

[fukurou]

classes

playground for multiple swift files :
file->new->project->macOS->command line tool

adding a file :
right click project folder->new file->swift file



help->developer documentation

class example with clone method (called copy in the swift language) :

class Enemy{
    var health : Int = 100
    var ATK : Int = 10
    func walk(){
        print("walked")
    }
    func copy()->Enemy{
        let clone = Enemy()
        clone.health = self.health
        clone.ATK = self.ATK
        return clone
    }
}

 

[fukurou]

optionals

crate a new Xcode project->macOS tab-> command line
optional binding

let myOptional:String? = "hadoken"
// transform optional to actual variable (optional binding)
if let safeOptional = myOptional {
    let text:String = safeOptional
    print(text)
}

nil coalescing operator :

let myOptional:String? = nil
/*
 nil coalescing operator
 the passed value will be the optional value or a default if the optional
 is a nil
 */
let text:String = myOptional ?? "it was a nil"
print(text) // prints it was a nil

optional chaning (a nil coalescing for object attributes)

struct MyOptionl{
    var property = 1234
    func method(){print("prints me")}
}

let myOptional: MyOptionl? = MyOptionl()
let text:Int = myOptional?.property ?? 25
print(text) // prints it was a nil

optional binding :

struct MyOptionl{
    var property = 1234
    func method(){print("prints me")}
}
let myOptional: MyOptionl? = MyOptionl()
// optional binding :
myOptional?.method() // (nil will not run)

 

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[fukurou]

swift getters and setters

class Weight {
    var kilograms: Float = 0.0
    var pounds: Float {
        get {
            return kilograms * 2.205
        }
        set(newWeight) {
            kilograms = newWeight / 2.205
        }
    }
}

 

[fukurou]

swift documentation markup

/// Some introductory test that describes the purpose
/// of the function.

/**
 What does this function do?
*/

func someFunction(name: String) -> Bool {
  return false
}

/**
 Another useful function
 - parameters:
   - alpha: Describe the alpha param
   - beta: Describe the beta param
*/
func doSomething(alpha: String, beta: String) {

/**
 Another useful function
 - parameter alpha: Describe the alpha param
 - parameter beta: Describe the beta param
*/
func doSomething(alpha: String, beta: String) {

for a function or method that returns a value include a returns section:

/// Some introductory test that describes the purpose
/// of the function.
/// - Returns: true or false

func someFunction() throws -> Bool {

list of keywords you can include anywhere in the description:

- Attention: Watch out for this!
- Author: Tim Cook
- Authors:
John Doe
Mary Jones
- Bug: This may not work
- Complexity: O(log n) probably
- Copyright: 2016 Acme
- Date: Jan 1, 2016
- experiment: give it a try
- important: know this
- invariant: something
- Note: Blah blah blah
- Precondition: alpha should not be nil
- Postcondition: happy
- Remark: something else
- Requires: iOS 9
- seealso: something else
- Since: iOS 9
- Todo: make it faster
- Version: 1.0.0
- Warning: Don't do it

Using Markdown​

quick example with some headings, lists, a code block and link:

/// ---
/// # Subtitle 1
/// ## Subtitle 2
/// This is a *boring* list:
/// + First point
///   1. subpoint with **bold text**
///
/// Some code - indented by four spaces
///
///     let flag = someFunction()
/// ---
/// seealso: [web site](url)