nhathm

// Get priview image for video
func previewImageFromVideo(_ url: URL) -> UIImage? {
    let asset = AVAsset(url: url)
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    imageGenerator.appliesPreferredTrackTransform = true
    
    var time = asset.duration
    time.value = min(time.value, 2)
    
    do {

nhathm

// Declare non-optionals variable
var notToday : String = "Tomorrow"

// Can't set non-optionals variable to nil
notToday = nil // Compile error

// Declare optionals variables
var dafug : String? = "Dafug"
var steps : Int? = 10

nhathm

let name : String? = "Swift"
let nickName : String? = nil

// Example: Optional binding
// Note: underscore "_" using to ignore name of parameter when call function
// Example calling function below
func sayHiWithOptionalBinding(_ name: String?) {
    // Using optional binding to check if object is NOT nil
    if let checkName = name {
        // If not nil, do some logic...

nhathm

let name : String? = "Swift"
let version : Int = 3
let owner : String = "Apple"

func checkMultiCondition(name : String?, version : Int, owner : String) {
    guard let name = name, version > 2, owner == "Apple" else {
        print("Input parameters not match!!!")
        return
    }
    print(name)

nhathm

struct Student {
    let name: String?
    let age: Int?
    let gender: String?
}

let student = Student(name: "Rio", age: 27, gender: "Male")

func validateStudentInfo (_ student: Student) -> String {
    // We do NOT need to using student name, just want to check if

nhathm

//: Playground - noun: a place where people can play
// nhathm01247@gmail.com

import UIKit

// Basic function declare
func sayHi() {
    print("Hi")
}
sayHi()

nhathm

import Foundation

// Declare a variable to hold a closure
var add: (Int, Int) -> Int

// Assign a closure to a variable
add = { (a: Int, b: Int) -> Int in
    return a + b
}

nhathm

// Declare a variable to hold a closure
var add: (Int, Int) -> Int

/** SHORTHAND SYNTAX **/

// Not need return keyword when only have single return statement
add = {(a: Int, b: Int) -> Int in
    a + b
}
add(1, 1)

nhathm

//: Playground - noun: a place where people can play
// nhathm01247@gmail.com

import Foundation

/** DECLARE A CLOSURE **/

// Declare a variable to hold a closure
var add: (Int, Int) -> Int

nhathm

//: Playground - noun: a place where people can play
// nhathm01247@gmail.com

import Foundation

// Requirement: write a function take Int, Int, Int and a function that sum first two Int params and then sub the third Int.

// Do it function way
// Declare a function
func add(_ a: Int, _ b: Int) -> Int {