PCH file for iOS development

The project's supporting files folder has a "project name-prefix.pch" file, which is also a header file

The contents of the PCH header file can be shared and accessed by all other source files in the project

In general, some global macros are defined in the PCH file

Add the following preprocessing directives in the PCH file, and then use the log (...) in your project. To output the log information, the NSLog statement can be removed at once when the application is published (debug mode is defined)

#ifdef DEBUG

#define LOG (...) NSLog (__va_args__)

#else

#define LOG (...)/* */

#endif

Detailed usage:

#import <Availability.h>

#ifndef __IPHONE_5_0

#warning "This project uses features only available in IOS SDK 5.0 and later."

#endif

/************__objc__begin************/

All content in the. m file or. mm

#ifdef __objc__

#import <UIKit/UIKit.h>

#import <Foundation/Foundation.h>

#import "MJPerson.h"

#ifdef DEBUG/debug phase

#define MJLOG (...) NSLog (__va_args__)

#else//Release phase

#define MJLOG (...)

#endif

#define ABC 10

#endif

/************__objc__end************/

/**

* Outside of everything, the whole project is shared

*/

#define NAME 10

/**

PCH file is useful:

1. Store some global macros (macros that are used throughout the project)

2. Used to include all header files (header files that are used throughout the project)

3. Can automatically turn on or off the log output function

*/

PCH file for iOS development