helloworldsmart

import UIKit
import CoreBluetooth

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {
    
    let centralManager:CBCentralManager!
    var connectingPeripheral:CBPeripheral!
    
    required init(coder aDecoder: NSCoder) {
        

helloworldsmart

```swift=
func perform(operation:String, a:Double, b:Double) -> Double! {
    var result:Double?
    switch operation {
    case "+":
        result = a + b
    case "-":
        result = a - b
    case "/":
        result = a / b

helloworldsmart

//inout類似C++傳遞引用
var image = [
    [3, 7, 10],
    [6, 4, 2],
    [8, 5, 4]
]

func raiseLowerValueOfImage(_ image:inout [[Int]]) {
    for row in 0..<image.count {
        for color in 0..<image[row].count {

helloworldsmart

enum Geometry: Int {
    case triangle = 3
    case square   = 4
    case pentagon = 5
    case hexagon  = 6
}

func drawGeometry(stepsLabel: Int, sides: Geometry) {
    let count = sides.rawValue
    let exteriorAngle = 360 / count

helloworldsmart

//: __Problem 4__
//:
//: __4a.__
//: Write an instance method, bark(), that returns a different string based on the value of the stored property, size.
enum Size: Int {
    case small
    case medium
    case large
}

helloworldsmart

func printer(mode: Int, size: Int) {
        guard size >= 2 else { return }
        switch mode {
        case 0:
            for i in 1...size {
                for _ in 1...i {
                    print("*", terminator: "")
                }
                print("")
            }

helloworldsmart

import UIKit

@IBDesignable
class FaceView: UIView {
    
    //Don't type infer
    @IBInspectable
    var scale: CGFloat = 0.9
    
    @IBInspectable

helloworldsmart

class FaceView: UIView {
    
    
    //MARK 
    //Don't type infer
    @IBInspectable
    var scale: CGFloat = 0.9 { didSet{setNeedsDisplay()} }
    
    @IBInspectable
    var eyesOpen: Bool = true { didSet{setNeedsDisplay()} }

helloworldsmart

import UIKit

class ViewController: UIViewController {

    //MART: 1. @IBOutlet weak var faceView: FaceView!
    
    //MART: 9.
    /*
     IBOutletweak var faceView: FaceView! {
     didSet {

helloworldsmart

class ImageViewController: UIViewController
{
    //1. model
//    var imageURL: URL?
    
    //5.
    var imageURL: URL? {
        didSet {
            image = nil
            //fetchImage()