To learn Swift Programming language, you haven't needed any previous programming knowledge, but the basic understanding of any other programming languages will help you to understand the Swift programming concepts quickly. A quick look at the example of Hello, World! Swift is a powerful and intuitive programming language for iOS, macOS, tvOS, and watchOS. Writing Swift code is interactive and fun, the syntax is concise yet expressive, and Swift includes modern features developers love. Swift code is safe by design, yet also produces software that runs lightning-fast. Swift 4 uses the same runtime as the existing Obj-C system on Mac OS and iOS, which enables Swift 4 programs to run on many existing iOS 6 and OS X 10.8 platforms. Audience This tutorial is designed for software programmers who would like to learn the basics of Swift 4 programming language from scratch. Learn the basic concepts, tools, and functions that you will eventually use to build both desktop and mobile applications with the popular programming language, Swift 2.This course is for complete and utter beginners to programming and Swift. If you don't know what fancy words like 'classes' and 'objects' mean then this is the course for you!
We’ll quickly move through some of the basics of Swift.
3.1 Printing and string interpolation
We can use
print
to print a value and ()
for string interpolation.3.2 Comments
Single line comments are declared by putting
//
at the beginning of a line.Multi-line comments are started using
/*
and ended by */
.3.3 Basic types
The basic types in Swift are:
3.3.1 Booleans
Booleans are of type
Bool
and can be either true
or false
. Anything in Swift that takes a boolean, must use a real boolean type.Swift is strict in its treatment of boolean values. Boolean is a type that can (only) be true or false. Any operator or function that expects a boolean must be given a boolean or the type system will complain. Many dynamic languages have a much looser definition of what kind of values can be truthy (for example, in Ruby anything that not nil or false is truthy. So an empty string can be used to represent true) - if you’re coming from one of those languages you’ll have to get used to only using booleans in places where booleans are expected.
Booleans are declared using the keyword
Bool
or by initializing them with true
or false
.3.3.2 Integers
Int
is the basic Integer type. There are also a number of Integer types of various sizes, both signed and unsigned.Listing 3.1 shows each of the Integer types along with their min and max values. For each of these types you can see their minimum and maximum values using the min
and max
properties.The full range of Integer types are Int, UInt, Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64
3.3.3 Floats and Doubles
Floating point numbers are represented using
Float
and Double
, depending on the precision that you need. Floats are represented using 32bits whereas Doubles are stored using 64 bits. Doubles have precision of at least 15 decimal places, whereas Floats can have as little as 6, depending on the value. Which one you use depends on how much precision you need. Here is an example where we lose precision by assigning a Float with more decimal places than it can handle.3.3.4 Strings and characters
Strings and characters are represented by the
String
and Character
types respectively.By default Swift will infer that something in double quotes is a String. But if we want it to be a character we can explicitly declare it as
Character
type. We can use the +
operator to concatenate two strings and we can use the Strings append
method to concatenate a character to a string.Both String and Character support unicode.
Figure 3.1 shows what the the above unicode strings look like in a playground.
Figure 3.1: Characters and Strings using unicode.
Like any other basic type, strings can be either mutable or immutable - depending on whether you declare them using let or var (more on this in chapter 4).
3.4 Some basic operators
The operators for addition, subtraction, multiplication, division and modulo are similar to the ones in most c-like languages.
Assignment uses
=
. Swift also has a number of compound assignment operators.We can also deconstruct assignment from tuples into vars (we cover tuples in more detail in chapter 8).
Comparison operators are similar in Swift to those in any other c-like language.
Logical operators are stricter than you may be used to. They return a boolean and each part of the expression must evaluate to a boolean. As outlined in Section 3.3.1 these operators must be used with boolean values, and they return a boolean value.
Swift has 2 operators for creating ranges. This is the syntax for creating a range in Swift.
The first version (called the closed range operator) includes 10 in the range. The second version (called the half-open range operator) doesn’t include 10 in the range.
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The ternary operator accepts a condition that evaluates to a boolean and then returns either the first or second branch depending on whether the initial expression was true or false.
3.5 Naming things
Swift programs use camel-case for all naming. To summarize:
- CamelCase for everything
- class names and top-level constants should be capitalized (i.e.
ClassName
) - method names, function names and variable names should start with a lower-case letter (i.e.
methodName
)
In going through these examples we’ve already encountered the syntax for declaring constants and variables in Swift, although we haven’t discussed it. In the next chapter we’ll cover that in a bit more detail.
The powerful programming language that is also easy to learn.
Swift is a powerful and intuitive programming language for macOS, iOS, watchOS, tvOS and beyond. Writing Swift code is interactive and fun, the syntax is concise yet expressive, and Swift includes modern features developers love. Swift code is safe by design, yet also produces software that runs lightning-fast.
Modern
Swift is the result of the latest research on programming languages, combined with decades of experience building Apple platforms. Named parameters are expressed in a clean syntax that makes APIs in Swift even easier to read and maintain. Even better, you don’t even need to type semi-colons. Inferred types make code cleaner and less prone to mistakes, while modules eliminate headers and provide namespaces. To best support international languages and emoji, Strings are Unicode-correct and use a UTF-8 based encoding to optimize performance for a wide-variety of use cases. Memory is managed automatically using tight, deterministic reference counting, keeping memory usage to a minimum without the overhead of garbage collection.
Declare new types with modern, straightforward syntax. Provide default values for instance properties and define custom initializers.
Add functionality to existing types using extensions, and cut down on boilerplate with custom string interpolations.
Quickly extend your custom types to take advantage of powerful language features, such as automatic JSON encoding and decoding.
Perform powerful custom transformations using streamlined closures.
These forward-thinking concepts result in a language that is fun and easy to use.
1password 7 3 1 cr2 battery. Swift has many other features to make your code more expressive:
- Generics that are powerful and simple to use
- Protocol extensions that make writing generic code even easier
- First class functions and a lightweight closure syntax
- Fast and concise iteration over a range or collection
- Tuples and multiple return values
- Structs that support methods, extensions, and protocols
- Enums can have payloads and support pattern matching
- Functional programming patterns, e.g., map and filter
- Native error handling using try / catch / throw
Designed for Safety
Swift eliminates entire classes of unsafe code. Variables are always initialized before use, arrays and integers are checked for overflow, memory is automatically managed, and enforcement of exclusive access to memory guards against many programming mistakes. Syntax is tuned to make it easy to define your intent — for example, simple three-character keywords define a variable ( var ) or constant ( let ). And Swift heavily leverages value types, especially for commonly used types like Arrays and Dictionaries. This means that when you make a copy of something with that type, you know it won’t be modified elsewhere.
Another safety feature is that by default Swift objects can never be nil. In fact, the Swift compiler will stop you from trying to make or use a nil object with a compile-time error. This makes writing code much cleaner and safer, and prevents a huge category of runtime crashes in your apps. However, there are cases where nil is valid and appropriate. For these situations Swift has an innovative feature known as optionals. An optional may contain nil, but Swift syntax forces you to safely deal with it using the ? syntax to indicate to the compiler you understand the behavior and will handle it safely.
Use optionals when you might have an instance to return from a function, or you might not.
Features such as optional binding, optional chaining, and nil coalescing let you work safely and efficiently with optional values.
Fast and Powerful
From its earliest conception, Swift was built to be fast. Using the incredibly high-performance LLVM compiler technology, Swift code is transformed into optimized native code that gets the most out of modern hardware. The syntax and standard library have also been tuned to make the most obvious way to write your code also perform the best whether it runs in the watch on your wrist or across a cluster of servers.
Swift is a successor to both the C and Objective-C languages. It includes low-level primitives such as types, flow control, and operators. It also provides object-oriented features such as classes, protocols, and generics, giving Cocoa and Cocoa Touch developers the performance and power they demand.
Great First Language
Swift can open doors to the world of coding. In fact, it was designed to be anyone’s first programming language, whether you’re still in school or exploring new career paths. For educators, Apple created free curriculum to teach Swift both in and out of the classroom. First-time coders can download Swift Playgrounds—an app for iPad that makes getting started with Swift code interactive and fun.
Aspiring app developers can access free courses to learn to build their first apps in Xcode. And Apple Stores around the world host Today at Apple Coding & Apps sessions where you can get hands-on experience with Swift code.
Source and Binary Compatibility
With Swift 5, you don’t have to modify any of your Swift 4 code to use the new version of the compiler. Instead you can start using the new compiler and migrate at your own pace, taking advantage of new Swift 5 features, one module at a time. And Swift 5 now introduces binary compatibility for apps. That means you no longer need to include Swift libraries in apps that target current and future OS releases, because the Swift libraries will be included in every OS release going forward. Your apps will leverage the latest version of the library in the OS, and your code will continue to run without recompiling. This not only makes developing your app simpler, it also reduces the size of your app and its launch time.
Open Source
Swift is developed in the open at Swift.org, with source code, a bug tracker, forums, and regular development builds available for everyone. This broad community of developers, both inside Apple as well as hundreds of outside contributors, work together to make Swift even more amazing. There is an even broader range of blogs, podcasts, conferences and meetups where developers in the community share their experiences of how to realize Swift’s great potential.
Cross Platform
Swift already supports all Apple platforms and Linux, with community members actively working to port to even more platforms. With SourceKit-LSP, the community is also working to integrate Swift support into a wide-variety of developer tools. We’re excited to see more ways in which Swift makes software safer and faster, while also making programming more fun.
Swift for Server
While Swift powers many new apps on Apple platforms, it’s also being used for a new class of modern server applications. Swift is perfect for use in server apps that need runtime safety, compiled performance and a small memory footprint. To steer the direction of Swift for developing and deploying server applications, the community formed the Swift Server work group. The first product of this effort was SwiftNIO, a cross-platform asynchronous event-driven network application framework for high performance protocol servers and clients. It serves as the foundation for building additional server-oriented tools and technologies, including logging, metrics and database drivers which are all in active development.
To learn more about the open source Swift community and the Swift Server work group, visit Swift.org
Playgrounds and Read-Eval-Print-Loop (REPL)
Much like Swift Playgrounds for iPad, playgrounds in Xcode make writing Swift code incredibly simple and fun. Type a line of code and the result appears immediately. You can then Quick Look the result from the side of your code, or pin that result directly below. The result view can display graphics, lists of results, or graphs of a value over time. You can open the Timeline Assistant to watch a complex view evolve and animate, great for experimenting with new UI code, or to play an animated SpriteKit scene as you code it. When you’ve perfected your code in the playground, simply move that code into your project. Swift is also interactive when you use it in Terminal or within Xcode’s LLDB debugging console. Use Swift syntax to evaluate and interact with your running app, or write new code to see how it works in a script-like environment.
Package Manager
Swift Package Manager is a single cross-platform tool for building, running, testing and packaging your Swift libraries and executables. Swift packages are the best way to distribute libraries and source code to the Swift community. Configuration of packages is written in Swift itself, making it easy to configure targets, declare products and manage package dependencies. New to Swift 5, the swift run command now includes the ability to import libraries in a REPL without needing to build an executable. Swift Package Manager itself is actually built with Swift and included in the Swift open source project as a package.
How Can I Learn Swift For Free
Objective-C Interoperability
You can create an entirely new application with Swift today, or begin using Swift code to implement new features and functionality in your app. Swift code co-exists along side your existing Objective-C files in the same project, with full access to your Objective-C API, making it easy to adopt.
Learn Swift Programming
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