Property wrappers in SwiftUI allow adding behavior to properties. This document discusses several property wrappers:
- @State - Manages a property value within a SwiftUI view and re-renders on change.
- @Binding - Creates a two-way binding between a property and its source of truth.
- @Published - Publishes changes to a property so observers can respond.
- @ObservedObject - Subscribes a view to changes in an observable object and re-renders.
- @EnvironmentObject - Provides an observable object to descendant views from an ancestor.
It provides examples of using these wrappers with MVVM in SwiftUI apps to manage state, share data
This presentation introduces some concepts about the Java Collection framework. These slides introduce the following concepts:
- Collections and iterators
- Linked list and array list
- Hash set and tree set
- Maps
- The collection framework
The presentation is took from the Java course I run in the bachelor-level informatics curriculum at the University of Padova.
Here is a basic Linear Algebra review for the class of Machine Learning. This is actually becoming a new class in the mathematics of Intelligent Systems, there I will be teaching stuff in
1.- Linear Algebra - From the basics to the Cayley-Hamilton Theorem with applications
2.- Mathematical Analysis - from set to the Reimann Integral
3.- Topology - Mostly in Hilbert Spaces
4.- Optimization - Convex functions, KKT conditions, Duality Theory, etc.
The stuff is going to be interesting...
**** Java Certification Training: https://www.edureka.co/java-j2ee-soa-training ****
This Edureka tutorial on “Arrays in Java” will talk about one of the pillars of Java fundamentals i.e Arrays. It will also take you through the various types of arrays in Java and how they are used to achieve various functionalities. Through this tutorial, you will learn the following topics:
1. Arrays in Java
2. Types of Arrays
3. Working with Arrays
4. Sorting in Arrays
5. Searching in Arrays
Check out our Java Tutorial blog series: https://goo.gl/osrGrS
Check out our complete Youtube playlist here: https://goo.gl/gMFLx3
Follow us to never miss an update in the future.
Instagram: https://www.instagram.com/edureka_learning/
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LinkedIn: https://www.linkedin.com/company/edureka
These slides are for the tutorial on how to use R language for data analysis and Machine Learning tasks.
The workshop was given at OSCON (Austin, TX), 2017
This presentation introduces some concepts about the Java Collection framework. These slides introduce the following concepts:
- Collections and iterators
- Linked list and array list
- Hash set and tree set
- Maps
- The collection framework
The presentation is took from the Java course I run in the bachelor-level informatics curriculum at the University of Padova.
Here is a basic Linear Algebra review for the class of Machine Learning. This is actually becoming a new class in the mathematics of Intelligent Systems, there I will be teaching stuff in
1.- Linear Algebra - From the basics to the Cayley-Hamilton Theorem with applications
2.- Mathematical Analysis - from set to the Reimann Integral
3.- Topology - Mostly in Hilbert Spaces
4.- Optimization - Convex functions, KKT conditions, Duality Theory, etc.
The stuff is going to be interesting...
**** Java Certification Training: https://www.edureka.co/java-j2ee-soa-training ****
This Edureka tutorial on “Arrays in Java” will talk about one of the pillars of Java fundamentals i.e Arrays. It will also take you through the various types of arrays in Java and how they are used to achieve various functionalities. Through this tutorial, you will learn the following topics:
1. Arrays in Java
2. Types of Arrays
3. Working with Arrays
4. Sorting in Arrays
5. Searching in Arrays
Check out our Java Tutorial blog series: https://goo.gl/osrGrS
Check out our complete Youtube playlist here: https://goo.gl/gMFLx3
Follow us to never miss an update in the future.
Instagram: https://www.instagram.com/edureka_learning/
Facebook: https://www.facebook.com/edurekaIN/
Twitter: https://twitter.com/edurekain
LinkedIn: https://www.linkedin.com/company/edureka
These slides are for the tutorial on how to use R language for data analysis and Machine Learning tasks.
The workshop was given at OSCON (Austin, TX), 2017
YouTube Link: https://youtu.be/C_oPLDaSy-8
**Java, J2EE & SOA Certification Training - https://www.edureka.co/java-j2ee-training-course **
This Edureka PPT on "design patterns in java" will provide you with detailed knowledge about Java Design Patterns and along with it, This PPT will also cover some real-time examples of some important Design Patterns in Java, in order to provide you with a deep understanding about their functionality. This PPT will cover the following topics:
Why do we need Design Patterns?
What are Design Patterns?
Structure of a Design Pattern
Types of Design Patterns
Creational Design Pattern
Structural Design Pattern
Behavioural Design Pattern
JEE Design Pattern
Overview of design patterns
Follow us to never miss an update in the future.
YouTube: https://www.youtube.com/user/edurekaIN
Instagram: https://www.instagram.com/edureka_learning/
Facebook: https://www.facebook.com/edurekaIN/
Twitter: https://twitter.com/edurekain
LinkedIn: https://www.linkedin.com/company/edureka
Castbox: https://castbox.fm/networks/505?country=in
OOAD Part A Question with answer and Part B & C questions.
References :
1) Previous University Questions.
2) Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and Iterative Development by Craig Larman.
3) Google search engine for text and images.
Collections Framework is a unified architecture for managing collections, Main Parts of Collections Framework
1. Interfaces :- Core interfaces defining common functionality exhibited by collections
2. Implementations :- Concrete classes of the core interfaces providing data structures
3. Operations :- Methods that perform various operations on collections
This presentation goes through what Inversion of Control is, which IOC patterns that exists, which of the patterns you should use and when you should use them.
These question are the basic questions for Interview based on Java language. These questions are able to crack the interview based on java language
Learn more at blog : --
https://solutionbyexpert.blogspot.com/2020/08/become-expert-secret-of-success-ii.html
#coding
#coding development skill program
#java
KAOS, is a goal-oriented software requirements capturing approach in requirements engineering. It is a specific Goal modeling method; another is i*. It allows for requirements to be calculated from goal diagrams.[1] KAOS stands for Knowledge Acquisition in automated specification or Keep All Objectives Satisfied.
The University of Oregon and the University of Louvain (Belgium) designed the KAOS methodology in 1990 by Axel van Lamsweerde and others. It is now widely taught worldwide at the university level for capturing software requirements.
YouTube Link: https://youtu.be/C_oPLDaSy-8
**Java, J2EE & SOA Certification Training - https://www.edureka.co/java-j2ee-training-course **
This Edureka PPT on "design patterns in java" will provide you with detailed knowledge about Java Design Patterns and along with it, This PPT will also cover some real-time examples of some important Design Patterns in Java, in order to provide you with a deep understanding about their functionality. This PPT will cover the following topics:
Why do we need Design Patterns?
What are Design Patterns?
Structure of a Design Pattern
Types of Design Patterns
Creational Design Pattern
Structural Design Pattern
Behavioural Design Pattern
JEE Design Pattern
Overview of design patterns
Follow us to never miss an update in the future.
YouTube: https://www.youtube.com/user/edurekaIN
Instagram: https://www.instagram.com/edureka_learning/
Facebook: https://www.facebook.com/edurekaIN/
Twitter: https://twitter.com/edurekain
LinkedIn: https://www.linkedin.com/company/edureka
Castbox: https://castbox.fm/networks/505?country=in
OOAD Part A Question with answer and Part B & C questions.
References :
1) Previous University Questions.
2) Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and Iterative Development by Craig Larman.
3) Google search engine for text and images.
Collections Framework is a unified architecture for managing collections, Main Parts of Collections Framework
1. Interfaces :- Core interfaces defining common functionality exhibited by collections
2. Implementations :- Concrete classes of the core interfaces providing data structures
3. Operations :- Methods that perform various operations on collections
This presentation goes through what Inversion of Control is, which IOC patterns that exists, which of the patterns you should use and when you should use them.
These question are the basic questions for Interview based on Java language. These questions are able to crack the interview based on java language
Learn more at blog : --
https://solutionbyexpert.blogspot.com/2020/08/become-expert-secret-of-success-ii.html
#coding
#coding development skill program
#java
KAOS, is a goal-oriented software requirements capturing approach in requirements engineering. It is a specific Goal modeling method; another is i*. It allows for requirements to be calculated from goal diagrams.[1] KAOS stands for Knowledge Acquisition in automated specification or Keep All Objectives Satisfied.
The University of Oregon and the University of Louvain (Belgium) designed the KAOS methodology in 1990 by Axel van Lamsweerde and others. It is now widely taught worldwide at the university level for capturing software requirements.
Overview of attributes (declaration|type) in the Swift programming language
Highlight: System Programming Interfaces (SP), an experimental attribute of Swift
In depth overview of the Flex data binding code generation. Provides info on accomplish data binding through actionscript as well as limitations of the process.
Compose is stable, it's time to integrate it into our apps! But it can be harder than expected and there are some questions to answer. Can the same architecture of a View-based app be reused or should we change it? Should the Compose code be aware of the architecture at all? And should the non UI code be changed to start using Compose? What can be replaced with a Composable, only the layouts or also something else?
Probably the best answer to all these questions is “it depends”, in this talk we’ll see some reasons and how to leverage Compose and the other tools to create a good architecture. Compose is more than just a UI framework and it can seem appealing to use it in a big portion of an app, a good architecture can be useful to limit this portion and use it only when necessary.
This was a presentation I wrote for a previous employer, aimed at Java developers. The goal was to help them understand some of the new UI conventions I was putting into their application, so that they would be able to develop "smarter" JSP code.
Chicago Coder Conference 2015
Speaker Biography: Wei Ru
Wei Ru has over 15 years of professional experience in design and development of Java enterprise applications across multiple industries. Currently he works as a technical architect at STA Group, LLC. He received a M.S. degree in Computer Science from Loyola University Chicago. As a software developer with an emphasis on Java, he strongly believes in software re-usability, open standards, and various best practices. He has successfully delivered many products using open source platforms and frameworks during his IT consultancies.
Speaker Biography: Vincent Lau
Vincent Lau has been Senior Architect at STA Group in Chicago for the last two years. He received a B.S. degree in Accounting and Finance from the University of Illinois at Chicago and worked on M.S. of Computer Science at DePaul University. He has over 15 years of software design, development, testing and project management experience on large enterprise distributed computing platforms. Most recently, he has worked on web based applications using Java, Spring, JavaScript, Angular.js, jQuery and web services. He previously had Senior Software Engineer and Lead positions in Royal Caribbean Cruises, Wells Fargo Bank, Cap Gemini America and Trans Union Corp.
Presentation: Practical AngularJS
AngularJS has been seen gaining momentum recently. Whether you want to develop a modern single-page application or to spice up only the view enabled by a traditional MVC web framework, AngularJS allows you to write cleaner, shorter code. AngularJS’ two-way data binding feature allows a declarative approach on views and controllers, and ultimately code modulization. With this strategic change and many features offered by AngularJS, learning AngularJS can be challenging. In this session, we will share some of the experiences we had in Angular UI development, we will cover:
AngularJS modules and common project setup
Communicating to a Restful service
Commonly used Angular functions, directives
UI Bootstrap, grid views and forms in AngularJS
Custom Angular directives
Asynchronous functions and event processing
Is your web app drowning in a sea of JavaScript? Has your client-side codebase grown from "a snippet here and there" to "more JavaScript than HTML"? Do you find yourself writing one-off snippets instead of generalized components? You're not the only one. Learn about a handful of strategies you can use to keep your JavaScript codebase lean, modular, and flexible. We'll cover all the major pain points — MVC, templates, persisting state, namespacing, graceful error handling, client/server communication, and separation of concerns. And we'll cover how to do all this incrementally so that you don't have to redo everything from scratch.
Analyzing source code of WPF examples by the Infragistics CompanyPVS-Studio
We continue analyzing various C# projects in order to show the abilities of the static code analyzer, PVS-Studio. In this article, we are providing analysis results of WPF examples by the Infragistics Company. Infragistics is a major software vendor, founded in 1989. It gained popularity mainly through the development of enterprise-ready user interface toolsets for developers, which are run on all platforms, including .NET.
In JS: CLASS <=> Constructor FN
new FN() => FN() { this }
FN = CLASS (FN = FN, FN = DATA)
Objects
Prototype / __proto__
Inheritence
Rewriting / Augmenting
built in objects
AngularJS primer, covering the pros and cons of AngularJS, basic concepts with code snippets, testing, caveats and a lot of links forward. It's good for getting a glimpse on AngularJS and getting hint on how to write your first templates, controllers, services, directives etc.
SC5 has used this training internally and given it to several customers with very successful results. The training has been given in a workshop form, is accompanied by a few practical exercises (that are not public yet).
The original set is made by SC5er Kari Heikkinen, published here by Lauri Svan for Aalto University course T-111.4360 Design of WWW Services.
3. Property wrappers in SwiftUI
• @Stat
e
• @Bindin
g
• @ObservedObjec
t
• @Publishe
d
• @EnvironmentObjec
t
• Etc
4. What is property wrappers?
A property wrapper adds a layer of separation between code that manages how a
property is stored and the code that defines a property. For example, if you have
properties that provide thread-safety checks or store their underlying data in a database,
you have to write that code on every property. When you use a property wrapper, you
write the management code once when you define the wrapper, and then reuse that
management code by applying it to multiple properties
.
https://docs.swift.org/swift-book/LanguageGuide/Properties.html
5. Example
import Foundation
struct AppSettings {
// Normal way
static shared = AppSettings()
var appLanguage: String {
get { UserDefaults.standard.value(forKey: "app_language") as? String ?? "" }
set { UserDefaults.standard.set(newValue, forKey: “app_language") }
}
var isLoggedIn: String {
get { UserDefaults.standard.value(forKey: "is_logged_in") as? Bool ?? false }
set { UserDefaults.standard.set(newValue, forKey: "is_logged_in") }
}
// Property wrapper
@PropertyWrapperUserDefault(key: "app_language", defaultValue: "") static var _appLanguage: String
@PropertyWrapperUserDefault(key: "is_logged_in", defaultValue: false) static var _isLoggedIn: Bool
}
// How to access
AppSettings.shared.appLanguage = "en"
AppSettings._appLanguage = “en"
6. How to create
import Foundation
@propertyWrapper
struct PropertyWrapperUserDefault<T> {
private var key : String
private var defaultValue: T
init(key: String, defaultValue: T) {
self.key = key
self.defaultValue = defaultValue
}
var wrappedValue: T {
get { UserDefaults.standard.value(forKey: key) as? T ?? defaultValue }
set { UserDefaults.standard.set(newValue, forKey: key) }
}
}
7. Example 2
Validate Phone number property wrappe
r
`ProjectedValue
`
Condition
s
- Phone number should have 10 character
s
- We can check it is true or false by access projectedValue
8. Example 2
import Foundation
@propertyWrapper struct PhoneNumberValidation {
var projectedValue: Bool = false
var storedValue: String = ""
init(wrappedValue: String) {
self.wrappedValue = wrappedValue
}
var wrappedValue: String {
get { storedValue }
set {
projectedValue = newValue.count == 10 ? true : false
storedValue = newValue.count < 10 ? newValue : String(newValue.prefix(10))
}
}
}
9. Example 2
struct Phone {
@PhoneNumberValidation var phoneNumber: String
func printPhoneNumber() {
print(phoneNumber)
print($phoneNumber)
}
}
let phone = Phone(phoneNumber: “1234”)
phone.printPhoneNumber()
// Result
1234
false
10. @State
A property wrapper type that can read and write a value managed by SwiftUI
.
SwiftUI manages the storage of any property you declare as a state. When the state
value changes, the view invalidates its appearance and recomputes the body. Use the
state as the single source of truth for a given vie
w
https://developer.apple.com/documentation/swiftui/state
11. @State
struct ContentView: View {
@State private var counter: Int = 0
var body: some View {
VStack {
Text("Counter: (counter)")
Button("Hit me", action: {
counter += 1
})
}.padding(16)
}
}
16. ProjectedValue of @State
/// A binding to the state value.
/// Use the projected value to pass a binding value down a view hierarchy.
/// To get the `projectedValue`, prefix the property variable with `$`
public var projectedValue: Binding<Value> { get }
17. @Binding
A property wrapper type that can read and write a value owned by a source of truth
.
Use a binding to create a two-way connection between a property that stores data, and
a view that displays and changes the data. A binding connects a property to a source of
truth stored elsewher
e
https://developer.apple.com/documentation/swiftui/binding
18. @Binding
struct ContentView: View {
@State private var randomNumber: Int = 0
var body: some View {
Text("1st horse number is: (randomNumber)")
CustomView(randomNumber: $randomNumber)
}
}
struct CustomView: View {
@Binding var randomNumber: Int
var body: some View {
Button("Hit me") {
self.randomNumber = Int.random(in: 1...100)
}
}
}
19. @Published
A type that publishes a property marked with an attribute
.
Publishing a property with the @Published attribute creates a publisher of this type. You
access the publisher with the $ operato
r
https://developer.apple.com/documentation/combine/published
21. @ObservedObject
A property wrapper type that subscribes to an observable object and invalidates a view
whenever the observable object changes
.
https://developer.apple.com/documentation/swiftui/observedobject
22. @ObservedObject
struct ContentView: View {
@ObservedObject var someObservable = SomeObservable()
var body: some View {
Text("Hello, (someObservable.userName)!”)
.padding()
}
}
23. @Published @ObservedObject
struct ContentView: View {
@ObservedObject var someObservable = SomeObservable()
var body: some View {
Text("Hello, (someObservable.userName)!")
.padding()
}
}
class SomeObservable: ObservableObject {
@Published var userName: String = ""
init() {
userName = “Ton"
}
}
24. @EnvironmentObject
A property wrapper type for an observable object supplied by a parent or ancestor view
.
An environment object invalidates the current view whenever the observable object
changes. If you declare a property as an environment object, be sure to set a
corresponding model object on an ancestor view by calling its environmentObject(_:)
modifier
.
https://developer.apple.com/documentation/swiftui/environmentobject
25. @EnvironmentObject
class UserSettings: ObservableObject {
@Published var userName = "Ton"
}
@main
struct EnvironmentObjectApp: App {
let userSettings = UserSettings()
var body: some Scene {
WindowGroup {
ContentView().environmentObject(userSettings)
}
}
}
struct ContentView: View {
@EnvironmentObject var userSettings: UserSettings
var body: some View {
Text("Hello, (userSettings.userName)")
.padding()
}
}
27. Let’s create a Project
MVVM with all property wrappers that I’ve talked about
.
- Display data from ViewModel to View (@Published, @ObservedObject
)
- Pass data between views (@Binding
)
- Update our view (@State
)
- Share data in our app (@EnvironmentObject)