Use of IOS. pch files

What is the. pch file
Precompiled header file (general extension. PCH) is a project in which the more stable code is pre-compiled and placed in a file (. PCH). These pre-compiled code can be any C/s code--or even an inline function--that is more stable throughout the project, i.e. code that is not often modified during engineering development.

My own understanding is  this. pch file is   defined as something that can be used in a. pch in any file within the entire project.
What is defined in the file and does not import any header files

My approach:
1. First, I'll add an. h file to write a macro definition

After the successful creation  , you can add some of the macro definitions you need in this file.  
For example: my

  header.h//  my9xiushow////  Created by Taoli on 16/12/15.//  Copyright 2016 LSS. All rights reserved.//#ifndef header_h#define header_h//Font Color # define RGBACOLOR (r,g,b,a) [Uicolor colorwithred: (r)/ 255.0 Green: (g)/255.0 Blue: (b)/255.0 alpha:a] #endif/* header_h */

I just added a macro to this side.

2. Create a. pch File New file-select PCH file

This allows you to create a. pch file   Sprefixheader

3. Connect the Header.h with the. pch file

Open a. pch file    Add import "Header.h"

#import <UIKit/UIKit.h> #import <Foundation/Foundation.h> #import "Header.h"

The code is as follows:

#ifndef sprefixheader_pch#define sprefixheader_pch//Include Any system framework and library headers this should be Included in all compilation units.//you'll also need to set the Prefix Header build setting of one or more of your Targ ETS To reference the this file. #import <UIKit/UIKit.h> #import <Foundation/Foundation.h> #import "Header.h" # endif/* SPREFIXHEADER_PCH */

4. Associating a. pch file with a project

buildsetting-Search Prefix header-Find prefix header

1 set the precompile prefix header  to Yes  so that the file is cached after compilation so that it   can speed up the compilation again
2 Prefix the Header  and then double-click and drag the newly created. pch file into it (try it a few times at a time and then just do it) drag it in and then change the directory to only the name of your   project./.pch filename  Just like I did  . My9xiushow/spreficheader.pch


5. This will be done: after  the commend+b compiled the project    and then you can use the

If for water  why not abandon the stormy sea

Use of IOS. pch files