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Learning Swift

Learning Swift

By : Andrew J Wagner
4.8 (5)
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Learning Swift

Learning Swift

4.8 (5)
By: Andrew J Wagner
Buy this Book

Overview of this book

If you are looking to build iOS or OS X apps using the most modern technology, this book is ideal for you. You will find this book especially useful if you are new to programming or if you have yet to develop for iOS or OS X.
Table of Contents (13 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Introducing Swift
1. Introducing Swift
Defining our goals for this book
Setting up the development environment
Running our first Swift code
Understanding playgrounds
Learning with this book
Summary
2
2. Building Blocks – Variables, Collections, and Flow Control
2. Building Blocks – Variables, Collections, and Flow Control
Core Swift types
Swift's type system
Printing on the console
Control flow
Functions
Bringing it all together
Summary
3
3. One Piece at a Time – Types, Scopes, and Projects
3. One Piece at a Time – Types, Scopes, and Projects
Structs
Classes
Enumerations
Projects
Extensions
Scope
Access control
Summary
4
4. To Be or Not to Be – Optionals
4. To Be or Not to Be – Optionals
Introducing optionals
Unwrapping an optional
Optional chaining
Implicitly unwrapped optionals
Debugging optionals
The underlying implementation
Summary
5
5. A Modern Paradigm – Closures and Functional Programming
5. A Modern Paradigm – Closures and Functional Programming
Functional programming philosophy
Closures
Building blocks of functional programming in Swift
Lazy evaluation
Curried functions
Summary
6
6. Make Swift Work for You – Protocols and Generics
6. Make Swift Work for You – Protocols and Generics
Protocols
Defining a generic
Extending the existing generics
Putting protocols and generics to use
Summary
7
7. Everything is Connected – Memory Management
7. Everything is Connected – Memory Management
How data is stored in a computer
Value types versus reference types
Automatic reference counting
Strong reference cycles
Lost objects
Summary
8
8. Writing Code the Swift Way – Design Patterns and Techniques
8. Writing Code the Swift Way – Design Patterns and Techniques
What is a design pattern?
Behavioral patterns
Structural patterns
Creational patterns
Using associated values effectively
Extending system types to reduce code
Lazy properties
Summary
9
9. Harnessing the Past – Understanding and Translating Objective-C
9. Harnessing the Past – Understanding and Translating Objective-C
Swift's relationship with Objective-C
The history of Objective-C
Constants and variables
Containers
Control flow
Functions
Types
Projects
Calling Objective-C code from Swift
Using functions
Summary
10
10. A Whole New World – Developing an App
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10. A Whole New World – Developing an App
Conceptualizing the app
Setting up the app project
Configuring the user interface
Running the app
Allowing picture taking
Temporarily saving a photo
Populating our photo grid
Refactoring to respect Model-View-Controller
Permanently saving a photo
Summary
11
11. What's Next? Resources, Advice, and Next Steps
11. What's Next? Resources, Advice, and Next Steps
Apple's documentation
Forums and blogs
Prominent figures
Podcasts
Summary
12
Index
Index

Temporarily saving a photo

To start, we will concern ourselves with how to temporarily store our pictures in memory. To do this, we can add an image array as a property of our view controller:

class ViewController: UIViewController {
    
    var photos = [UIImage]()
    
    // ...
}

As we saw in the image picker delegate method, UIKit provides us a UIImage class that can represent images. Our photos property can store an array of these instances. This means that the first step for us is to add new images to our property when the callback is called:

    func imagePickerController(
        picker: UIImagePickerController,
        didFinishPickingImage image: UIImage!,
        editingInfo: [NSObject : AnyObject]!
        )
    {
        self.photos.append(image)
        self.dismissViewControllerAnimated(true, completion: nil)
    }

Now, every time the user takes or picks a new photo, we add it to our list, which stores all the images in the memory. However, this isn't quite enough, as we also...

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