Dark Horse Programmer--Simple OC Program

Knowledge points

1. #import的用途:

1>, like # include, copies the contents of a file

2> can automatically prevent the contents of a file from being copied repeatedly

2. #import <Foundation/NSObjCRuntime.h>

Declaration of nslog function in NSObjCRuntime.h

Path to 3.Foundation frame header file

1> Right-click Xcode.app-Show Package Contents

2> xcode.app/contents/developer/platforms/iphoneos.platform/developer/sdks/iphoneos6.0.sdk/system/library/ Frameworks/foundation.framework

4. main header file

1> main header file: The most important header file, the name is usually the same as the frame name, including all other header files in the frame

The primary header file name for the 2> Foundation framework is Foundation.h

3> only need to contain the foundation framework Master header file, you can use the whole framework of things

5. Operation Process

1> writing OC source files:. m,. C

2> compilation: Cc-c xxx.m xxx.c

3> Link: cc XXX.O xxx.o-framework Foundation

(Only the foundation framework is used to add the-framework Foundation)

4> run:./a.out

 1, OC introduction ? On the basis of the C language , a minimal object-oriented syntax is added. ? fully compatible with C language ? You can mix C code , even C + + code , in OC code ? applications that can use OC to develop Mac OS X platform and IOS platform

2. OC Syntax preview 1. Keywords? basically all keywords start with @ ? Here are some common keywords , take a look at the line , do not go through the data to find their meaning

@interface,@implementation,@end

@public,@protected,@private,@selector

@try,@catch,@throw,@finally

@protocol,@optional,@required,@class

@property,@synthesize,@dynamic

Self,super,ID,_cmd,__block,__strong,__weak,

2. string starts with @

For example @"Hello" is a string in OC , and "Hello" is a string in C language

3. Other Syntax

3, the development process of OC program

Similar to the C language :

4. The first 1 OC procedure 1. Code Writing

c language, oc The entrance of the program is still main function except to write a .m file such as here is a main.m file ( Span class= "S27" and file name can be Chinese )

1 #include <stdio.h>23//  OC Program entry: main function 4int Main () 5 {6     printf (" 1th oc program \ n"); 7     return 0 ; 8 }

2. Terminal Instructions ? compile cc –c main.m ? link cc main.o ? run ./a.out

5. The first 2 OC procedure 1. Code Writing

A bit different from C, using the NSLog function to output content

1 #import <Foundation/Foundation.h>23int  main ()4{  5     //  NSLog output will be automatically wrapped 6     NSLog (@ " 2nd OC Program!!! "); 7     8     return 0 ; 9 }

2. Terminal Instructions ? compile cc –c main.m ? link cc main.o –framework Foundation ? run ./a.out

3. The difference between NSLog and printf ? NSLog receives the OC string as a parameter,printf receives the C language string as a parameter ? NSLog after output, does not wrap automatically after printf output ? #import <Foundation/Foundation.h> required to use NSLog ? using printf requires #include <stdio.h>

4. The role of #import ? As with #include , to copy the contents of a file ? can automatically prevent the file content to be copied multiple times, it is not necessary to add the following preprocessing instructions in the header file

#ifndef ? _stdio_h_

#define? _stdio_h_

#endif

5. Role of the Foundation framework ? Develop The necessary framework for OC, IOS, MAC programs ? This framework contains a number of commonly used APIs(application programming interfaces) ? The framework contains a lot of header files, if you want to use the contents of the entire framework, including its main header file can be

#import <Foundation/Foundation.h>

6. use of BOOL ? The nature of the BOOL type

typedef signed char BOOL;

? There are 2 values for variables of type BOOL :YES,NO

#define YES (BOOL)1

#define NO (BOOL)0

? output of BOOL (as integer )

NSLog(@ "%d%d", YES, NO);

1#import <Foundation/Foundation.h>2 3 4 BOOL Test (bool Mybool)5 {6     returnNO;7 }8 9 intMain ()Ten { OneBOOL B =YES; A      -BOOL B2 =NO; -      theBOOL B3 =1;//YES -      -BOOL B4 =0;//NO -      +      -     //NSLog (@ "%i", b); +      ANSLog (@"%d", Test (YES)); at     return 0; -}

6. The first 3 OC procedure 1. Development of multiple. m files

is the same as the development of multiple. c Files in C language

1) write 3 files ? main.m

#import "One.h"

int Main ()

{

test();

return 0;

}

? one.h

void test ();

? ONE.M

#import <Foundation/Foundation.h>

void Test ()

{

NSLog(@ " call the test function ");

}

2) terminal Instructions ? compile:cc –c main.m test.m ? Link:cc main.o TEST.O –framework Foundation ? run:./a.out

2. . M file and . C File Mix development 1) write 3 files ? main.m

#import "One.h"

int Main ()

{

test();

return 0;

}

? one.h

void test ();

? one.c

#include <stdio.h>

void Test ()

{

printf(" call the test function \ n");

}

2) terminal Instructions ? compile:cc –c main.m test.m ? Link:cc main.o TEST.O ? run:./a.out

( no-framework Foundation is used without the foundation Framework )

Dark Horse Programmer--Simple OC Program