The Swift Playgrounds app makes programming easy and fun. Is it possible to develop on an iPad?

This is all we need to write in header file. IBAction allows you to connect a method to a user interface element, for example, in response to a button click, the program code we have written will be called.

So, we said that we will call the string with the text label and that the buttonClick method will be called in response to user action. Let's write the code for this method. Let's switch to the ViewController.m file in the project tree. After the line @implementation... add the code

Note, if you copied this code, you will probably get an error when you run the program, most likely the problem is in the quotes. Delete them and enter them from the keyboard.

Let's figure out what we see here. We access the label object - a line of text on the screen. Since this is an object, it has various data inside it (which in OOP are also called object properties) and methods that can be accessed by placing a dot after the object name. The text property is responsible for the text contained within a string.

We've completed the coding, all that's left is to associate the label and buttonClick with the elements inside the design layout. Click on the MainStoryboard_iPhone.storyboard line in the Project Navigator window to switch to the interface designer. Then click on the “View controller” icon. Switch to connections mode in the inspector (last icon). Look, the label line has appeared in the Outlets area of ​​the inspector. This is the name that we specified in the ViewController.h file. Click the circle on the right side of the label line and drag it onto the Some Text line in the design layout.

Do a similar operation with the button. Click on the button with a circle in the “Received Actions” group, then click on buttonClick and drag it onto the button in the layout. As a result, it will open context menu, with which you can select when to call the method. You can, for example, call the code when the user presses the button, or when he releases it. There are many options. Select "Touch up Inside".

That's all! Save the project and click on the "Run" button on the top panel. If you did everything correctly, the emulator with your program should start. Click the button. The text in the line should change. That's all. The first lesson is over

The profession of a programmer is one of the most prestigious and in demand, that’s a fact. In the development industry software have their own niches. Of these, the fastest growing, and at the same time the most highly paid, is software development for mobile devices. As you know, it just so happened that, leaving their competitors far behind, three constant rivals took the lead. The trick is that one of these three is the undisputed leader, while someone always catches up.

In the mobile technology segment, Apple is undoubtedly the leader with its iPhone smartphone. At a presentation held in September, the Cupertino company demonstrated the 7th version of the mobile device. Along with it, Apple introduced a new version of its mobile operating system. iOS systems 10. Now it is the most significant operating system in the world, like its predecessors. It follows from this that learning iOS development is the most profitable investment time and money.

Apple ecosystem

Today we will develop a simple mobile application for iOS. Of course, a native Mac is best suited for this. But if you are a Windows supporter or you simply don’t have a Mac, you can install operating system macOS under virtual machine on Windows. In the vastness of the Internet, it won’t be difficult for you to find one specially designed for PC. macOS version, popularly called Hackintosh. Feel free to install it on a VMware virtual machine, VirtualBox - your choice. Let me warn you right away that the PC keyboard does not have some of the keys that are on the Mac keyboard, and many of their combinations cannot be pressed in Hackintosh. This pretty much spoils the mood. Otherwise, all the operations described below can be successfully performed on Hackintosh.

Required knowledge

To program in general and for iOS in particular, you need to know quite a lot. Mathematics and logic may not be needed at first, but they will be in demand later. Modern technologies relieved the programmer of the need to thoroughly know the computer architecture, but it was necessary to understand basic mechanisms such as number systems, their conversion, the speed of subroutines or the efficiency of algorithms (big O).

For more high level An iOS developer needs to have a deep knowledge of the macOS operating system and iOS itself. You also need to master the Apple programming language. Knowledge of Delphi, C++, C# or VB.NET will not help you much. Apple has its own ecosystem with its own languages: Objective-C and Swift. Of course, knowledge of C++ has never harmed anyone; programs and inserts based on it are found everywhere, even at Apple. But the most used by definition is Objective-C, simply because it appeared much earlier (in the mid-eighties of the last century), while Swift only two years ago (in 2014). Apple has high hopes for new language and invests a lot in it. Objective-C is used to support the old software, and the new one is written in Swift. So it's good for you to know both.

In order not to waste time, all these programming languages ​​can be learned under the strict supervision of teachers on the website.

Development Tools

As you know, the main developer tool for macOS and with it iOS is the programming environment Xcode. It includes tools for creating applications for Mac, iPhone, iPad, Apple TV, Apple Watch. All Apple platforms. Xcode contains Interface Builder, a code editor that supports everything modern means working with code. In addition, without leaving Xcode, you can test the application; if it is developed for an external device, then it can be run in an emulator.

The system includes emulators of all devices, new versions of which can be downloaded. In addition, Xcode contains graphical tools for analyzing application performance, including tools for diagnosing CPU load, storage usage (HDD, SDD and others), load on the graphics adapter (from the OpenGL side).

On September 13, a new, hotly anticipated version of the development environment 8.0 was released. Stable versions can be downloaded for free from the App Store. Alphas and betas are distributed by developer subscription. The eighth version includes: a new version of the Swift 3 language, a learning tool for Swift Playground for iPad, a new version of Interface Builder, which has become faster and allows you to view the application layout on different platforms, without the need to deploy the application itself on the simulator.

With Xcode 8 you can develop applications for macOS Sierra, iOS 10, watchOS 3 and tvOS 10. All SDKs included. New versions of operating systems began to appear consistently right after Apple presentations, held in early September.

Objective-C language

Let us briefly recall the basic information about the language. Objective-C is a compiled object-oriented programming language used for writing applications for Apple systems. It is a superset or, in other words, an add-on to C, inheriting from the latter syntax, data types, methods of monitoring the progress of program execution and adding object-based capabilities to it oriented programming- description of classes and methods.

As in C++, in Objective-C the central role is played by objects, which are associated with four paradigms: abstraction, encapsulation, inheritance, polymorphism. C++ is a strongly typed language, while Objective-C is weakly typed or has a dynamic data type system. Like Smalltalk, Objective-C sends messages to objects. This is an exceptional opportunity dynamic languages, because the type of objects is checked at runtime, not at compile time.

The description of the Objective-C language takes up more than one voluminous volume. Therefore, in order to gain objective knowledge, it is convenient to take the “” course. An entire section of the course is dedicated to this language.

iOS application development

As a sample we will develop a very simple application. Let us not deviate from the sacred tradition, let us greet the world. However, taking into account the fact that we graphic application, we will diversify it a little: we will add a button, when clicked, we will display or hide the inscription “Hello, World”.

Launch Xcode, in the window that appears, select Create new project or in the main menu File -> New -> Project. The next window will ask you to select the target platform and application type.

In this case, we are interested in the iOS platform. There are seven types of applications to choose from. Six of them are templates for typical applications of the iOS operating system, containing a different set of components by default. The seventh type is play.

Application Types

• The Single View Application template is intended for simple application with one screen. The preset includes a View Controller component, which allows you to customize the appearance of the application using the Interface Builder form designer.
• Master Detail Application creates an application where table view a collection of objects is displayed. After selecting one of them, detailed information about that object is shown. The first view is the master, the second is the detailing.
• Page-Based Application creates applications that have multiple screens, like pages in a book. Consequently, e-readers are created from this blank.
• Tabbed application allows you to create applications where each screen can be switched to at any time, that is, each screen has its own button to activate it, on which the title is displayed. An example is iTunes.
• Game is used to create a game template. There are four frameworks to choose from for creating a game: SpriteKit, SceneKit, OpenGL ES, Metal. Let's look at them briefly.
  SpriteKit is a system for 2D rendering and animation of textured rectangles - sprites. When displaying frames, a standard loop is used, the frame is displayed after all the contents of the scene have been processed.
  SceneKit is a high-level visualization framework 3D graphics without the help of OpenGL. It supports downloading, manipulation three-dimensional objects. It includes: a physics engine, a particle generator and an easy scripting method.
  OpenGL ES is the industry standard computer graphics. Allows you to visualize 2D and 3D scenes. Allows you to describe the pipeline for a video card: vertices undergo transformation, are assembled into primitives, which are rasterized into a two-dimensional image and displayed on the screen. Programmable shaders can be included in the pipeline.
  Metal is a low-level API that will allow you to get the most out of your video adapter. Debugged APIs along with precompiled shaders and multi-threading allow your game to rise to the top. new level productivity and quality.
• Sticker Pack Application - the new kind apps introduced in iOS 10 and Xcode 8. It is a set of simple or animated images used in the new iMessage. It does not require coding to create it.
• iMessage Application is a new type of application that appeared in iOS 10 and Xcode 8. Allows you to create add-ons for iMessage, for example to purchase and download your sticker pack. You can also use the iMessage API to create your own analogue this application, including playing audio, video, using stickers and more.

Creating the first project

As a template for our application, we will select Single View Application. Since we won't develop big program, the funds provided by this provision will be enough for us. Click Next. On next page The wizard must enter the name of the project, for example ShowLab. In the Language drop-down list, leave the default language selected - Objective-C. Next, in the Devices drop-down list, leave the Universal selection. Here you determine for which device (iPhone or iPad) the application is being created. The Universal clause means for both. Let's uncheck the Include Unit Tests and Include UI Tests boxes; we don't need any tests. Next. Select a folder to save the project. Now click the Create button.

As a result, a window will open with a list of all parameters applied to the project. In this window, you can change the parameters previously set in the wizard: orientation, target device, etc.

First we need to create the application interface. To do this, select the Main.storyboard file in the list on the left with one click (if this file is not visible, expand the contents of the ShowLab folder). To the right of the list, the entire window will be occupied by Interface Builder. The device layout will be displayed in the center. In the lower right corner of the window there is a component panel. Drag the Label and Button components from there onto the layout. Above the component panel is a list of properties. If you don’t have it, click the Show the Attributes Inspector button, located under the window title on the right side of the interface.

Select the Label component in the layout and configure its Text property: leave the Plain selection in the drop-down list, enter the desired inscription in the line below, in our case “Hello, World”. If the text does not fit within the borders of the label, change them by dragging the handles on the edges of the component. To centralize it horizontally, go to the Size Inspector page by clicking on the Show the Size Inspector button (to the right of Show the Attributes Inspector). On this page, from the Arrange drop-down list, select Center Horizontally in Container.

Now select the Button component, change its Text property to the desired label - Switch. You can center it in the same way as described above.

Creating a connection between graphic elements and code

IN Visual Studio(or Delphi) object in the code is created automatically the moment you place a visual component on the form. This doesn't happen in Xcode, but it doesn't cause problems.

Open the contents of the ViewController.h header file in separate window by double-clicking on it. This file contains a declaration of an extension of the UIViewController class, marked with the @interface keyword. This feature was added to the second version of Objective-C. Now do this trick: move the mouse cursor to a component - a text label, hold down Ctrl key And left button mice. Move the cursor to the window with the code (file ViewController.h), a blue line will follow the cursor. Release the mouse and key inside the ViewController interface description.

The Outlet creation window will appear.

This is a property of an object that refers to another object (in this case, a visual component). You need to enter the name of the Outlet object, by which you will access the visual component, let it be lab. Next, the object type is selected, it is selected correctly: UILabel.

Even lower in the Storage list, select the type of object reference: weak or strong. If you choose strong, then the object pointed to by the property will exist as long as the property points to it, in which case it will not be automatically deleted when it is no longer used. On the other hand, when a weak reference is in effect, the object can self-destruct. So, select the weak link type and click the Connect button. As a result, the following line will be added to the code:

@property (weak, nonatomic) IBOutlet UILabel *lab;

Let's make sure that Outlet is a property.

Now let's create an Outlet for the button. The algorithm remains the same. Only for the Name property you need to enter a different name, for example but. The line will be added to the code:

@property (weak, nonatomic) IBOutlet UIButton *but;

As a result, we have two pointers to visual components: lab and but - respectively, an inscription and a button. Now, using pointers, we can manipulate components in code.

Then you need to create a button click event handler. To do this, open the implementation file ViewController.m in a separate window. In exactly the same way as you dragged the line into the header file to create the outlet, from the button, drag the line into the implementation file and drop it to the closing command bracket - @end. A window for creating an event will appear, similar to the window for creating an outlet. You see the difference: a link to an object is created in the header file, a method is created in the implementation file.

Fill in the Name field, its value represents the name of the property - method. Let it be onClick. Leave the Type field value as default - id. In Objective-C this type is the ancestor of everyone else. In the Event drop-down list, the Touch Up Inside event is selected by default, which occurs when the pointer (mouse, finger...) is released over the button, that is, the final stage of pressing the button. That's what we need. In the Arguments list, we will leave the default value: Sender is the object that sent this signal, in our case it will always be a button. Click the Connect button. As a result, the following code will be added:

- (IBAction)onClick:(id)sender ( )

A minus at the beginning means private method(private). Keyword IBAction tags the events (methods) of visual components from Interface Builder.

Between the command brackets we will write the code that is executed when the button is pressed:

Lab.hidden = !_lab.hidden;

In this line of code we invert the value properties hidden. It is of type BOOL, which has two values: YES - true and NO - false (somewhat unusual for Windows programmers, where true and false).

Pay attention to the underscore character before the name of the object - the label (_lab). Without it, compilation will fail with an error. The underscore is added automatically for objects contained within other objects; that is, in this case, the lab object is contained in the ViewController object. Previously, this was a convention used to distinguish between objects declared as members of a class and local objects. And now this is a strict rule implemented in the language compiler.

Now you can compile the application and run it on the simulator. We chose the simulator for iPhone 7, included in Xcode 8. The compile and run button is a black rectangle and is located in the bar at the top of the interface.

After compiling the application, launching the simulator and loading our application, its interface will be displayed on the simulator screen: the inscription “Hello, World” and the Switch button. If you press the last one, the inscription will disappear; if you press it again, it will appear again.

We have made a very simple application to understand the essence of iOS development. You can learn more detailed information about creating iOS applications in Objective-C from the course by our friends from GeekBrains “”. The course devotes two months to learning this language. During the first month - introductory topics, and in the second - real coding of professional applications.

Swift language

IN 2014 year Apple introduced a new programming language - Swift. It quickly became the most talked about and fastest growing language in the world. It's reliable, safe, intuitive clear language for developing applications for the operating systems macOS, iOS, tvOS and watchOS for the entire fleet of Apple devices. Swift- effective language programming. It's easier to learn than its predecessor, Objective-C, and Swift borrows some of its best ideas. At the same time, the developers have made the languages ​​compatible, that is, one program can contain code in both Swift and Objective-C. There are billions of lines of code and hundreds of thousands of legacy programs written in Objective-C in the world, so its support will definitely not be abandoned.

At Swift development The goal was to create the most convenient system programming language - fast, safe and expressive.

The algorithm in Swift is 2.6 times faster than the same algorithm in Objective-C, and 8.4 times faster than in Python. Using Swift makes the program development process more flexible and convenient.

Thanks to its exponential development, December 3, 2015 Swift language has been contributed to the open source community. At the same time, Apple strictly monitors its development, organizing a committee for its development. Now Swift is available not only in Apple systems, but also on Linux. All additional tools for working with the language, including a debugger, standard library, manager package, also free and open.

This language is the future. You can find out more detailed information about it from the mentioned course from GeekBrains “”, in which a whole month is devoted to studying of this language programming.

App Store

Simply put, the App Store is a content store for the entire range of Apple devices. Here you can buy games and applications from both large companies and independent developers. Every developer, no matter what country he lives in, can sell or distribute his programs for free on this digital distribution platform. To start doing this, you need to register as a developer and buy a license to sell your applications. This is a fee for the service provided and development App store Store.

Results

We have developed a simple application for the iOS mobile operating system using the Xcode programming system along with the Objective-C language. Tested ready application on the iPhone 7 simulator. We learned how to build a user interface using Interface Builder, how to associate graphic elements with application code, and how to create event handlers. We got acquainted with the basics of Objective-C. In addition, we drew attention to promising language Swift, used to develop powerful and secure applications for the Apple ecosystem.

However, the material studied is only the beginning. In order to intensively upgrade yourself in the direction of mobile coding and the development of actually selling applications, we recommend taking the “” course on our friends’ website.

This is a worthy course: if you take it, you definitely won’t waste your time. It starts with two detailed courses on Java language, followed by learning basic programming for the Android mobile operating system. Next is a course on databases in general and the SQL language in particular. Then an in-depth course on developing professional Android applications. After this, the vector of study will move towards Apple systems: two detailed courses on the Objective-C language and a useful course on Swift.

The course lectures are taught by professional teachers with extensive experience in software development. If something is unclear, you can ask a question without delay. In general, learning on GeekBrains is a live process, you can communicate, ask questions, and help with answers. To test the acquired knowledge, teachers issue homework, which is then checked. After completing the training, you will have a guaranteed internship in an IT company. And then everything depends on you, if you show yourself as a competent specialist, you will be invited to work.

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