Xamarin.iOS introduction

Creare app native su
iOS, Android, Mac &
Windows in C#
Introduzione a Xamarin.iOS

Gli speaker di oggi
Guido Magrin
Xamarin & Microsoft Student Partner
Xamarin Certified Developer
@GuidoMagrin

Dove trovo le slide?
http://www.slideshare.net/guidomagrin

Gli Xamarin Student Partner
https://www.facebook.com/XSAMilano

Oggi parleremo di…
Xamarin.iOS

Chi ha già
sentito parlare di
Xamarin.iOS?

Xamarin + Xamarin.Forms
Approccio offerto da Xamarin.Forms:
Codice UI condiviso, controlli nativi
Approccio tradizionale di Xamarin
Shared UI Code

.NET + iOS APIs | copertura al 100%

Qualsiasi cosa si possa fare in Objective-C
o Swift può essere fatta in C#
con Xamarin in Visual Studio

Xamarin è sempre aggiornato
Release iOS supportate al day-one:
iOS 5, iOS 6, iOS 7, iOS 7.1, iOS 8, iOS 9, iOS 10
Supporto ad Apple Watch!

Xamarin Studio
PC o Mac
Plugin Visual Studio
VS 2010 e superiore
Ambienti di Sviluppo

Integrazione in Visual Studio
Una soluzione sola per:
• iOS
• Android
• Windows Phone
• Windows Store
Tutti i plugin e le funzioni
di Visual Studio:
• ReSharper
• Team Foundation Server

Integrazione in Visual Studio
Debugging su:
• Emulatori
• Dispositivi
Integrati nella toolbar:
• Stato
• Logs
• Lista di dispositivi

Xamarin Studio
• Ottimizzato per lo sviluppo
cross-platform
• Accedi alle API native con
l’autocompletamento
• Designer per Android e iOS
• Debugging avanzato su
emulatore o dispositivo

Designer per Xamarin iOS
• Il primo designer iOS
presente in Xamarin Studio e
Visual Studio
• Simile al designer
tradizionale di Visual Studio
• Supporta pienamente l’UIKit
• Modifica i componenti
personalizzati e di terze parti
• Modifiche grafiche applicate
in tempo reale

Cosa impareremo oggi?
• Fundamentals
• The package
• Views and navigation
• Managing lists
• Working files

Before we start...
• You need a Mac:
– OS X 10.9.4+
– Xcode
– Xamarin.iOS
• You can still work on your Windows PC:
– Visual Studio
– Xamarin.iOS

Before we start...
• The OS X and Windows machines have to be connected
to the same network
• You can connect a OS X machine only to multiple
Windows machines
• OS X and Windows need to have the same Xamarin.iOS
version installed

iPhone simulator
• Requires the latest version of Xamarin.iOS.
• Allows you to “completely forget” about your
Mac.
• Fun fact: given that the Windows PC has a
touchscreen, it supports this kind of input.

What if I don’t have a Mac? Rent one!
• Always available.
• Pay as you go.
• Scalable according to our needs.

The application
• Main
– It’s the entry point of the app
– It creates the application
• AppDelegate
– It manages the system events
– It has an Application Window with the UI
– It starts the Main interface

The startup
• Storyboard
– Takes care of initializing the main controller
– The controller manages the main view and the sub views
• ViewController
– It receives the interactions
from the views
– It takes care of displaying
the data on the view

Apple Watch has Storyboards, too!
• Same functionalities you would expect from iPhone storyboards.
• As of today, easier to work with in terms of app rescaling.

Model-View-Controller (MVC)
• iOS is based on MVC
– The Model describes the data
– The View describes the UI
– The Controller manages the interactions
between the Model and the View

Domanda 1
Posso creare applicazioni iOS usando esclusivamente un PC Windows
a) Vero
b) Falso

Domanda 2
Da quali componenti è composta un’applicazione iOS?
a) Main, AppDelegate
b) Window, AppDelegate
c) Main, ViewController
d) Screen, ViewController

Resources
• iOS requires that all the resources are placed in the root
folder
• Xamarin adds a Resource folder
– At compile time, the content is copied in the root
• The Build Action has to be set to BundleResource

Images
• The original iPhone had a resolution of 320x480
• New resolutions have been added
• Naming conventions to manage the assets:
– @2x -> Retina
– @3x-> iPhone 6 Plus
– ~iphone -> Used on the iPhone
– ~ipad -> Used on the iPad
– Example: Image.png, Image@2x.png,
Image2x~iphone.png

Info.plist and Entitlements.plist
iPhone Deployment info
• It contains the main info about the app
configuration:
– Main interface
– Supported orientations
– Status bar style
Entitlements
• Used to configure iCloud,
push notifications, HealthKit, etc.

Domanda 1
Se volessi implementare iCloud nella mia app iOS, tramite quale file
dovrei abilitarne l’integrazione?
a) BundleResources.plist
b) Info.plist
c) CloudConnectivity.plist
d) Entitlements.plist

Storyboards
• In the past, iOS developers managed views using the
XIB files
• Each XIB files was mapped with a controller
• The developer needed to manually manage the
navigation between two views

Storyboards
• A storyboard is the visual representation of all the
screens in an app
• It’s made by different scenes
• A scene is a View managed by a ViewController
• Scenes contains objects and controls that are used to
manage interactions and to display data

The Xamarin designer
• Storyboards can’t be created in code
• The underline XML is generated automatically by
the designer
• Xamarin offers a built-in designer, which requires
a Mac Build Host connected to the Windows
machine

Navigation
• Navigation in Storyboards is managed using
Segues
• A Segue is a transition between two scenes
• Multiple transitions:
– Simple navigation
– Modal views
– Popover
• Segues are created using the designer

Storyboards, Segues and Xamarin designer

Domanda 1
Come si chiama il file contenente tutte le schermate della mia app iOS?
a) Segues
b) Storyboard
c) Designer
d) BuildHost

Domanda 2
Cosa uso per navigare tra le varie pagine della mia app iOS?
a) Navigator
b) Arrow
c) Transitioner
d) Segues

Passing data
• A storyboards offers a method called
PrepareForSegue() to override
• You get a reference to the destination control and
you pass the data into a property
public override void PrepareForSegue(UIStoryboardSegue segue, NSObject sender)
{
base.PrepareForSegue(segue, sender);
var controller = segue.DestinationViewController as MyPageController;
controller.TextToShow = MyPhoneNumber.Text;
}

Conditional navigation
• Sometimes you need to perform navigation only if a
specific condition is satisfied
• You can override the ShouldPerformSegue()
method
public override bool ShouldPerformSegue(string segueIdentifier, NSObject sender)
{
if (segueIdentifier == "SegueToMainPage")
{
if (PasswordTextField.Text == "password") return true;
else return false;
}
return base.ShouldPerformSegue(segueIdentifier, sender);
}

The view’s lifecycle
Methods intherited by the UIViewController class
• ViewDidLoad
– The controller has loaded the connected view
• ViewWillAppear
– The pagecontent is about to appear
• ViewWillDisappear
– The page content is about to disappear
• ViewDidAppear / ViewDidDisappear
– The page content is appeared / disappeared

Alerts
If you target a pre iOS 8 device, you need to use the
UIAlertView class
UIAlertView av = new UIAlertView("Title",
"message",
null,
"OK",
null);
av.Show();

Alerts
If you target an iOS 8+ device, you can use:
• UIAlertController to display an alert
• UIActionSheet to display an action sheet

Built-in applications
• Same URI-based approach that you find in Windows
Phone
• You use the OpenUrl() method to invoke a URL
NSUrl url = new NSUrl("http://www.xamarin.com");
if (UIApplication.SharedApplication.CanOpenUrl(url))
{
UIApplication.SharedApplication.OpenUrl(url);
}

Table Views
Many different classes and APIs to implement a list
• UITableView
– It’s the table that contains the rows to display
• UITableViewCell
– It represent a row of the list
• UITableViewSource
– It’s a specific Xamarin class that makes easier to implement a
UITableView
– On iOS, you would to implement separately the
UIViewTableDataSource and UITableViewDelegate classes

Table Views
Many different classes and APIs to implement a list
• NSIndexPath
– It identifies a specific element of the table
• UITableViewController
– It’s the controller that implements an UITableView

Table layout
• Four different built-in styles
• To implement a custom layout, you need to implement a
custom cell

Creating a UITableViewSource
• You need to choose a cell identifier
• You need to implement the GetCell() method to define the
layout of a cell
public class TableSource : UITableViewSource
{
string[] tableItems;
string cellIdentifier = "TableCell";
public TableSource(string[] items)
{
tableItems = items;
}
public override nint RowsInSection(UITableView tableview, nint section) { }
public override UITableViewCell GetCell(UITableView tableView, Foundation.NSIndexPath
indexPath)
{
...
}
}

Cell reuse
• It’s the technique used to improve performances in case
of big collections to display
• You first ask for a cell to reuse before creating a new one
public override UITableViewCell GetCell(UITableView tableView, Foundation.NSIndexPath
indexPath)
{
UITableViewCell cell = tableView.DequeueReusableCell(cellIdentifier);
// if there are no cells to reuse, create a new one
if (cell == null)
cell = new UITableViewCell(UITableViewCellStyle.Default, cellIdentifier);
cell.TextLabel.Text = tableItems[indexPath.Row];
return cell;
}

Cell reuse
Starting from iO6, there’s a new method that automatically
takes care of generating the proper cell for you
public override UITableViewCell GetCell(UITableView tableView, NSIndexPath
indexPath)
{
var cell = (MyCell)tableView.DequeueReusableCell(MyCellId, indexPath);
return cell;
}

Domanda 1
Di quali metodi e controlli mi posso avvalere per creare una lista in
un’app iOS?
a) UITableView
b) UITableViewContainer
c) UITableViewSource
d) UITableViewCell

Domanda 2
Per implementare un Custom Layout, devo implementare una Custom
Cell
a) Vero
b) Falso

Domanda 3
Quante tipologie di Layout di default sono presenti?
a) Due
b) Quattro
c) Otto
d) Dodici

Using a custom layout
• You need to create a custom cell
• You can do it in code or with the designer
• You add the controls inside
the UIViewTableCell object
• In code, you assign a value to the controls

Using a custom layout
In the UITableViewSource, you use the custom cell class
instead of the base UITableViewCell one in the GetCell()
method
public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
{
CharacterCellView cell = tableView.DequeueReusableCell(CellIdentifier, indexPath) as
CharacterCellView;
Character currentCharacter = tableItems[indexPath.Row];
cell.UpdateCharacter(currentCharacter);
return cell;
}

Files and folders
• To create files and folder you can leverage the basic .NET
APIs (System.IO)
• Documents is the base path where all the files of the
application are stored
• In the info.plist you can
set the option
UIFileSharingEnabled
to true to allow access
to local files through
iTunes

The folders
• Library
– To store the internal files of the application
– It’s automatically backed up
• Library/Preferences
– To store the application settings
– It’s automatically backed up
• Library/Caches
– iOS can delete the content in case the space is going low
– It’s not backed up

Working with
files and folders
DEMO

Grazie per l’attenzione 
Guido Magrin
Xamarin Student Partner
@GuidoMagrin

Xamarin.iOS introduction

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