For a string object (in Objective-C, this is an instance of the class NSString), the class offers various ways to examine and convert the internal characters that it represents. Classes Are Blueprints for ObjectsĪ class describes the behavior and properties common to any particular type of object. This interface includes the list of messages that the class can receive, so you also need to provide the class implementation, which contains the code to be executed in response to each message.
#CLASS PREFIX XCODE 6 HOW TO#
This chapter demonstrates how to define classes in Objective-C by declaring an interface, which describes the way you intend the class and its instances to be used.
In object-oriented programming terms, an object is an instance of a class. The app development process involves deciding how best to customize and combine the objects provided by the underlying frameworks with your own objects to give your app its unique set of features and functionality. Some are designed for you to customize with your own code to behave in the way you require. Some of these objects are immediately usable, such as basic data types like strings and numbers, or user interface elements like buttons and table views.
For OS X or iOS development, you don’t need to create objects from scratch to solve every conceivable problem instead you have a large library of existing objects available for your use, provided by Cocoa (for OS X) and Cocoa Touch (for iOS). Objects in Objective-C are just like objects in other object-oriented programming languages: they package data with related behavior.Īn app is built as a large ecosystem of interconnected objects that communicate with each other to solve specific problems, such as displaying a visual interface, responding to user input, or storing information. When you write software for OS X or iOS, most of your time is spent working with objects.
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