Mac App Development Tutorial Objective C

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Mac App Development Tutorial Objective C 5,7/10 5866 votes

Mac App Development Tutorial Objective Chart
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Apple’s Xcode development system is superb for developing applications, but sometimes you just want to write C or C++ code for research or school. Composing a serious chunk of code with vi is no longer acceptable,* so users in this frame of mind are now using Eclipse, a modern IDE, that’s also free. Here’s how to get gcc without installing Apple’s Xcode and then install Eclipse for C/C++ programming.

May 21, 2019 I’ve also created an objective-c function that is called every time the. Make sure to follow the Apple tutorial on creating MacOS apps with. These are the basics for Mac Development. Apr 18, 2017 The OpenGL ES app should build and run successfully and you will see a colored 3D spinning cube. Build and run the app on iOS. The iOS project created in the solution can be edited in Visual Studio, but because of licensing restrictions, it must be built and deployed from a Mac. Xamarin is a cross-platform mobile development framework that now ships with Visual Studio 2019 for Windows and Visual Studio for Mac. It is a thin wrapper around the native APIs and tooling, so anything you can do in Java/Kotlin for Android, or Objective-C/Swift for iOS, you can do in Xamarin using the C# goodness we know and love. It starts with Objective-C, the base language on which the native iOS software development kit (SDK) and the OS X are based. Learn Objective-C on the Mac: For OS X and iOS, Second Edition updates a best selling book and is an extensive, newly updated guide to Objective-C. Sep 17, 2014 About Objective-C. Objective-C is the primary programming language you use when writing software for OS X and iOS. It’s a superset of the C programming language and provides object-oriented capabilities and a dynamic runtime. Objective-C inherits the syntax, primitive types, and flow control statements of C and adds syntax for defining.

What’s the Motivation?

At work recently, my wife was chatting with a colleague who was taking his first C++ class. She taught him how to use Eclipse on a Mac, even though he resisted at first. However, later, he came back and commented that the other students were trying to manage ever increasingly complex projects with the vi editor. It was taking them four, six, or even 20 hours in some cases to complete their homework each week. He finished his, typically, in 30 minutes. That’s the power of an IDE with a modern debugger. That last item, the debugger, can’t be emphasized enough. Print statements in your code are oh, so yesteryear with a tool like this. Time is money, and efficiency reflects on you as a programmer.

So if you’re a scientist, researcher or engineer who wants to write some research code, not intended as a GUI app, in Java, C, C++ or Fortran, you need to dump vi as an editor* (or Emacs or Nedit or whatever) immediately and get with this kind of IDE. Things are moving far too fast nowadays not to make this important move. (Clearly, I’m speaking to an older crowd here.**)

To be perfectly clear, Apple’s Xcode is a fabulous development system for C, C++, Objective-C and even Fortran 77***. You can build native OS X and iOS apps. But many researchers and scientists aren’t interested in Xcode. They’ve come from a Linux or other UNIX platform, like IBM’s AIX, and they just want to carry on their research in Eclipse on a Mac. This how-to is primarily for them. But, as I mentioned above, students who are taking their first programming class and own a Mac will also find this discussion useful — indeed mandatory. Remember, this is an introduction to whet your appetite and get you launched, not a complete Eclipse tutorial.

Also, this how-to for the sake of simplicity focuses on C/C++, but Eclipse can handle a myriad of languages, including, but not limited to, Java and Fortran. Let’s start with C/C++.

Getting the gcc Compiler

As an aside, when you install Apple’s Xcode (free from the Mac App Store only in Lion), gcc is automatically installed in /usr/bin. But if you have a mind to work with just Eclipse and gcc, you’ll need a way to install gcc without, if it pleases you, installing Apple’s Xcode first. (For reference, here’s a how-to on installing Xcode and gcc.)

There are at least two places I know of where you can get a gcc installer package for OS X:

The OS X High Performance Computing page at Sourceforge managed by Dr. Gaurav Khanna at the University of Mass.

If you find other sources, let us know.

Installing Eclipse

Here’s a handy reference on where to get Eclipse for the Mac. Version 3.7 (“Indigo”) installs nicely in Lion and seems to work okay, but our household hasn’t put it to a grueling acid test with OS X 10.7.1.

Eclipse Download for CC++, 64-bit

The download is a …tar.gz file, so move it where you want the Eclipse directory to be because when you double click it, the package will be unzipped and untared right there. After Eclipse is installed, you’ll see it as an app, just like any other, with this icon.

It’s easy to create an alias to eclipse.app, if you wish, and place it in your /Application directory. Because the Eclipse IDE itself is written in Java, if you’re running a clean copy of Lion, you’ll need to download the Java runtime before the Eclipse app will launch. Just double-click on Eclipse, and it’ll trigger the required Java runtime download. Nothing else to do. If you’re in Snow Leopard, the Java runtime is already there.

Java runtime download

This first thing you’ll see when you run Eclipse is that it asks for the location of your workspace. I typically create a directory in /Users/john called Programming where I do any code development. (Which is not much these days.)

Workspace Selection

After you select your workspace, you’ll be confronted with an Eclipse peculiarity. A welcome page will be launched that brings a real feeling of WTF to many users. Here it is.

Welcome screen

The trick is to realize that the icon on the far right, circled in red above, takes you into the workbench. For that named workspace, this one time is the only time you’ll see that screen.

Once the IDE is launched, there are just a few details before you can build a project. Again, for simplicity, lets stay with C/C++. From the Eclipse File menu, select “New” and then C++ Project.

Eclipse - New Project

Experienced Eclipse users know the drill. Name the project, make sure you’ve identified the location of your compiler in the Toolchain, and so on. (It may be different than the default install by Apple’s Xcode. The screen shot below shows Apple’s install of gcc, marked as MacOSX GCC, because I’d previously installed Xcode on that Mac.)

Configuration

Compile macos app as library. Newbies may want to select the Hello World project just to see how things get set up. Make sure you work your way through the setup with Next > at the bottom and don’t click the Finish button too soon. A more detailed examination of this set up and the ins-and-outs of Eclipse are beyond the scope of this getting started article. The goal here is simply an introduction for Mac users. And you’re not alone. There’s a huge body of knowledge on the Internet about Eclipse. Here’s a start.

If all went well, you’ll be in the Eclipse IDE with the Hello World program in the editor and a Make file already created. This environment is called the Eclipse workbench.

Eclipse Workbench w/ default “Hello World” code

It may take you some start-up time to learn Eclipse, but trust me, coding the old way will soon bog you down. The Xcode and Eclipse developers learn from each other, so if you ever decide to get into OS X or iOS development, having earned your wings in Eclipse will pay huge dividends later.

__________________

* I’m qualified to say this because I’ve lived and breathed vi for a living in the past.

** Remember, a lot of people are going back to school, learning or refreshing their programming skills.

*** You can write and compile Fortran 77 in Xcode with standard output, but you can’t access the Cocoa APIs and build native apps in F77.

Objective-C is the primary programming language you use when writing software for OS X and iOS. It’s a superset of the C programming language and provides object-oriented capabilities and a dynamic runtime. Objective-C inherits the syntax, primitive types, and flow control statements of C and adds syntax for defining classes and methods. It also adds language-level support for object graph management and object literals while providing dynamic typing and binding, deferring many responsibilities until runtime.

At a Glance

This document introduces the Objective-C language and offers extensive examples of its use. You’ll learn how to create your own classes describing custom objects and see how to work with some of the framework classes provided by Cocoa and Cocoa Touch. Although the framework classes are separate from the language, their use is tightly wound into coding with Objective-C and many language-level features rely on behavior offered by these classes.

An App Is Built from a Network of Objects

When building apps for OS X or iOS, you’ll spend most of your time working with objects. Those objects are instances of Objective-C classes, some of which are provided for you by Cocoa or Cocoa Touch and some of which you’ll write yourself.

If you’re writing your own class, start by providing a description of the class that details the intended public interface to instances of the class. This interface includes the public properties to encapsulate relevant data, along with a list of methods. Method declarations indicate the messages that an object can receive, and include information about the parameters required whenever the method is called. You’ll also provide a class implementation, which includes the executable code for each method declared in the interface.

Relevant Chapters:Defining Classes, Working with Objects, Encapsulating Data

Categories Extend Existing Classes

Rather than creating an entirely new class to provide minor additional capabilities over an existing class, it’s possible to define a category to add custom behavior to an existing class. You can use a category to add methods to any class, including classes for which you don’t have the original implementation source code, such as framework classes like NSString.

If you do have the original source code for a class, you can use a class extension to add new properties, or modify the attributes of existing properties. Class extensions are commonly used to hide private behavior for use either within a single source code file, or within the private implementation of a custom framework.

Protocols Define Messaging Contracts

The majority of work in an Objective-C app occurs as a result of objects sending messages to each other. Often, these messages are defined by the methods declared explicitly in a class interface. Sometimes, however, it is useful to be able to define a set of related methods that aren’t tied directly to a specific class.

Objective-C uses protocols to define a group of related methods, such as the methods an object might call on its delegate, which are either optional or required. Any class can indicate that it adopts a protocol, which means that it must also provide implementations for all of the required methods in the protocol.

Relevant Chapters:Working with Protocols

Values and Collections Are Often Represented as Objective-C Objects

It’s common in Objective-C to use Cocoa or Cocoa Touch classes to represent values. The NSString class is used for strings of characters, the NSNumber class for different types of numbers such as integer or floating point, and the NSValue class for other values such as C structures. You can also use any of the primitive types defined by the C language, such as int, float or char.

Collections are usually represented as instances of one of the collection classes, such as NSArray, NSSet, or NSDictionary, which are each used to collect other Objective-C objects.

Blocks Simplify Common Tasks

Blocks are a language feature introduced to C, Objective-C and C++ to represent a unit of work; they encapsulate a block of code along with captured state, which makes them similar to closures in other programming languages. Blocks are often used to simplify common tasks such as collection enumeration, sorting and testing. They also make it easy to schedule tasks for concurrent or asynchronous execution using technologies like Grand Central Dispatch (GCD).

Relevant Chapters:Working with Blocks

Error Objects Are Used for Runtime Problems

Although Objective-C includes syntax for exception handling, Cocoa and Cocoa Touch use exceptions only for programming errors (such as out of bounds array access), which should be fixed before an app is shipped.

All other errors—including runtime problems such as running out of disk space or not being able to access a web service—are represented by instances of the NSError class. Your app should plan for errors and decide how best to handle them in order to present the best possible user experience when something goes wrong.

Objective-C Code Follows Established Conventions

When writing Objective-C code, you should keep in mind a number of established coding conventions. Method names, for example, start with a lowercase letter and use camel case for multiple words; for example, doSomething or doSomethingElse. It’s not just the capitalization that’s important, though; you should also make sure that your code is as readable as possible, which means that method names should be expressive, but not too verbose.

In addition, there are a few conventions that are required if you wish to take advantage of language or framework features. Property accessor methods, for example, must follow strict naming conventions in order to work with technologies like Key-Value Coding (KVC) or Key-Value Observing (KVO).

Relevant Chapters:Conventions

Prerequisites

If you are new to OS X or iOS development, you should read through Start Developing iOS Apps Today (Retired) or Start Developing Mac Apps Today before reading this document, to get a general overview of the application development process for iOS and OS X. Additionally, you should become familiar with Xcode before trying to follow the exercises at the end of most chapters in this document. Xcode is the IDE used to build apps for iOS and OS X; you’ll use it to write your code, design your app's user interface, test your application, and debug any problems.

Although it’s preferable to have some familiarity with C or one of the C-based languages such as Java or C#, this document does include inline examples of basic C language features such as flow control statements. If you have knowledge of another higher-level programming language, such as Ruby or Python, you should be able to follow the content.

Reasonable coverage is given to general object-oriented programming principles, particularly as they apply in the context of Objective-C, but it is assumed that you have at least a minimal familiarity with basic object-oriented concepts. If you’re not familiar with these concepts, you should read the relevant chapters in Concepts in Objective-C Programming.