LESSONS LEARNED. SWIFTDagna Bieda, 7th April 2016

SWIFT & XCODEBrief Intro

“ Language that essentially marries the readability of Python with the speed of C++.

@jeremyconkin

SWIFT

➤ mix of good practices from multiple languages, rooted in C,

➤ statically typed language,

➤ no nil as we know it, let n = nil // type of expression is ambiguous without more context

let i : Int? = nil // the result is actually Optional<Int>.None

➤ all variables must be initialized before using them,

➤ memory management done by Automatic Reference Counting,

➤ object-oriented, functional, generic, protocol-oriented,

SWIFT

➤ very large community,

➤ massive amount of free tutorials (www.raywenderlich.com),

➤ recently open-sourced,

➤ possible to create server backend using Kitura-IBM or Perfect

SWIFT. WHERE TO LEARN FROM

➤ stackoverflow.com

➤ youtube.com: Stanford - Developing iOS 8 Apps with Swift

➤ udacity.com:

A. Intro to iOS App Development with Swift

B. iOS Developer Nanodegree

➤ edx.com

➤ coursera.com

XCODE

➤ enforces type-safety, // var was never changed, consider changing to let

➤ integrated with control management systems - git and SVN,

➤ code coverage, profiling, memory usage, leaks,

➤ test recording,

➤ storyboards <3

HEALTH CAREapp case study

APP REQUIREMENTS

➤ Facilitate communication between patient and their nurse,

➤ Share health data of the patient on a daily basis,

➤ Share videos and/or documents,

➤ Simple management of multiple patients,

➤ Be easy to use (non tech-savvy users)

DEMO APP + TEST

CODE EXAMPLESimport GRDB

enum UserType: String, DatabaseValueConvertible { case Nurse = "Nurse", Patient = "Patient"

var databaseValue: DatabaseValue { get { return DatabaseValue(object: self.rawValue)! } }

static func fromDatabaseValue(databaseValue: DatabaseValue) -> UserType? { let value = databaseValue.value() as! String return UserType(rawValue: value) }

func toggled() -> UserType { switch self{ case .Nurse : return .Patient case .Patient : return .Nurse } } }

CODE EXAMPLESprotocol DashboardDrawable { func setupAt(origin: CGPoint, xOffset: CGFloat, size: CGSize, addToView masterView: UIScrollView) }

class MessageView: UIView, DashboardDrawable {

func setupAt(origin: CGPoint, xOffset: CGFloat, size: CGSize, addToView masterView: UIScrollView){ var frame = CGRect(origin: origin, size: size) frame.origin.x += xOffset self.frame = frame self.backgroundColor = UserSettings.messageViewColor self.addLabels() masterView.addSubview(self) } }

CODE EXAMPLESprotocol DashboardDrawable { func setupAt(origin: CGPoint, xOffset: CGFloat, size: CGSize, addToView masterView: UIScrollView) }

class MessageView: UIView, DashboardDrawable {

func setupAt(origin: CGPoint, xOffset: CGFloat, size: CGSize, addToView masterView: UIScrollView){ var frame = CGRect(origin: origin, size: size) frame.origin.x += xOffset self.frame = frame self.backgroundColor = UserSettings.messageViewColor self.addLabels() masterView.addSubview(self) } }

// Usage in DashboardDetailTableViewController private func preparePatientDataForCell(cell: PatientDataCell, patient: Patient, date: NSDate, viewSize: CGSize) {

let width = computeDashboardsElementWidth(viewSize.width) let size = CGSize(width: width, height: viewSize.height)

let matchPatientsIdAndSelectedDate = { (cp: ContactPointProtocol) -> Bool in return cp.patientId == patient.serverId && cp.date ~= date }

for message in dbWrapper.messages.filter(matchPatientsIdAndSelectedDate) { let view = MessageView(message: message)

let offset = timeline.calculateDateOffset(message.date) view.setupAt(CGPointZero, xOffset: offset, size: size, addToView: cell.patientDashboard) } }

CODE EXAMPLESprotocol DateDisplayButtonDelegate: class { func dateDidChange(newDate: NSDate) }

class DateDisplayButton: UIButton {

var date: NSDate! { // ! deferred initialization didSet{ if oldValue != date { let components = NSCalendar.currentCalendar().components([.Month, .Day, .Weekday], fromDate: date) let weekday = Weekday(rawValue: components.weekday)!.description let month = Month(rawValue: components.month)!.description let day = components.day let title = String("\(weekday), \(month) \(day)") self.setTitle(title, forState: .Normal)

if oldValue != nil { delegate?.dateDidChange(date) } } } } var delegate: DateDisplayButtonDelegate? }

! ?

CODE EXAMPLESprotocol DateDisplayButtonDelegate: class { func dateDidChange(newDate: NSDate) }

class DateDisplayButton: UIButton {

var date: NSDate! { didSet{ if oldValue != date { \\ ... if oldValue != nil { delegate?.dateDidChange(date) } } } } var delegate: DateDisplayButtonDelegate? }

class DashboardDetailTableViewController: UIViewController, UITableViewDelegate, UIScrollViewDelegate, UIPopoverDelegate, DateDisplayButtonDelegate {

@IBOutlet weak var dateDisplayButton: DateDisplayButton! { didSet { dateDisplayButton.delegate = self } }

// MARK: DateDisplayButtonDelegate func dateDidChange(newDate: NSDate) { preparePatientsData(newDate) } }

CODE EXAMPLESprivate extension UIColor { class var random: UIColor { switch arc4random()%5 { case 0: return UIColor.greenColor() case 1: return UIColor.blueColor() case 2: return UIColor.orangeColor() case 3: return UIColor.redColor() case 4: return UIColor.purpleColor() default: return UIColor.blackColor() } } }

// Tuples and _ placeholder class TimelineDashboardHeader: UIScrollView { var majorTics = [NSDate : (String, (UILabel, UIBezierPath))]() var minorTics = [NSDate : (String, UIBezierPath)]()

func calculateDateOffset(date: NSDate) -> CGFloat{ let roundedDate = roundedDownToNearestHalfHour(date)

var tic: UIBezierPath? = UIBezierPath() if let (_, (_ , tic)) = majorTics[roundedDate] { let roundedX = tic.currentPoint.x let timeDistance = CGFloat(date.timeIntervalSinceNow - roundedDate.timeIntervalSinceNow) let xOffset = roundedX + (timeDistance/majorTicsTimespan * intervalSize) return xOffset } else { return 0.0 }

}

NOT SO FUN PART➤ casting Int or Double to CGFloat

func frameForMenuButton(indexPath: NSIndexPath) -> CGRect { let row = indexPath.row / numberOfColumns let column = indexPath.row % numberOfColumns

let originX: CGFloat = floor((itemSize.width + horizontalSpace) * CGFloat(column)) let originY: CGFloat = floor((itemSize.height + verticalSpace) * CGFloat(row))

return CGRectMake(originX, originY, itemSize.width, itemSize.height) }

➤ mysterious UIScrollView ➤ “in” to denote end of a closure’s type signature ➤ protocol with a settable variable has to be restricted to classes (it not a struct with a mutating setter which should be allowed)

THANK YOU!

#ifdef greatPresentation

#include ”standing-ovation.hpp”

#endif