IOS review notes: Objective-C syntax Basics

IOS review notes: Objective-C syntax Basics

I. Syntax Basics

1 keyword

The keywords basically start with @. Common keywords are as follows:

@ Interface, @ implement, @ end, @ public, @ private, @ selector, @ required, @ encode, etc.

Other IDs, self, super, etc.

 

2. the string starts @.

@ "Hello world! "

 

3 Boolean Yes/No

 

4. null type nil (value: 0)

 

5 other C language syntax

 

2 OC HelloWorld Program

 

// Helloworld. m # import
 
  
# Include
  
   
Int main () {printf ("OC fully compatible with C \ n"); NSLog (@ "Hello World"); // automatically wrap return 0 ;}
  
 

 

 

In Mac, cc is compiled using clang.

Compile:

 

cc -c helloworld.m

 

A hellowold. o will be generated under the current folder.

Link:

 

cc hellowork.o -framework Foundataion

A. out will be generated under the current folder.

 

Run:

 

./a.out

It will be printed on the screen:

 

Fully compatible with C
19:10:49. 451 a. out [503: 507] HelloWorld

 

3-plus files

 

// main.m#import "helloworld.h"int main(){    show();    return 0;}

# Import
 
  
# Include
  
   
// Helloworld. hvoid show () {printf ("OC fully compatible with C \ n"); NSLog (@ "HelloWorld ");}
  
 

Compile and generate the. o file:

 

 

cc -c main.m

Link generation a. out

cc main.o

The running mode and result are the same as above.