Learning Objective-C and Xcode

Objective-C is a combination of C and Small Talks

The trick is to understand the symbols and keywords

Understanding the Language Symbols

at the heart of Objective-C is C.

It's not important to know which are pure

{   his is the begin brace    Blocks are used to defin and surround a section of code and define its scope.

- (void)methodName It represents what type of information the method represents. 

* pointer 

[] Thease are called brackets and are used when sending a message to an Objective-C object 

@identify an Objective-C directive 

#import

- (void)logMesage

{

　　NSString *hell =  @"Hello World!";

　　NSLog(hello); 

}

@ is an Objective-C directive and is a quick way of defining a constant string object

MSLog method

Objective   is basis in Smalltalk

Pretty much everything is an object.

Objec

 

The @interface compiler directive

The identical object-oriented notion of inheritance works in Objective-C and many Cocoa touch classes.

remember the initial capital letter convention.

@interface NewSubclass : SuperClass

@symbol are called compiler directives.

tells the compiler that this section contains declarations of the variables and methods that will be fleshed out in the companion @implementation section .

a custom class needs far more infrastructure than what you'll be defining in the class files.

NSObject  the most fundamental classs in the Foundation framework.

Foundation, UIKit and other frameworks inherit from NSObject

Using Xcode to Create DGCar Class Files

choose Cocoa Touch Class in the left column, then Objective-C class in the top right group

specify hat this will be a subclass of NSObject.

 

#import <Foundation/Foundation.h>

@intarface DGCar : NSObject {

 

}

@end

 

转载于:https://www.cnblogs.com/yushunwu/archive/2012/07/23/2604362.html