An extension of Objective-c: Extension

The following is a little bit of knowledge I learned during my learning process. Although it is superficial, I want to share it with you! I hope to give more advice.

First look at the code structure
Test
Main. m
SceneManager. h
SceneManager. m

SubSceneManager. h

SubSceneManager. m

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The following is code implementation:

SceneManager. h

# Import <Foundation/Foundation. h>

@ Interface
SceneManager: NSObject

-(Void)
Go;
@ End

SceneManager. m

# Import
"SceneManager. h"

// Extend the Class-A method of hiding the wrap method (unforced)
@ Interface
SceneManager ()
+ (Void) wrap;
@ End

@ Implementation
SceneManager

-(Id) init
{
Self = [super init];
If (self ){
// Initialization code here.
}

Return self;
}

-(Void) go {
NSLog (@ "method of go ");
}

+ (Void) wrap {
NSLog (@ "method of wrap ");
}

@ End

SubSceneManager. h

# Import
"SceneManager. h"

@ Interface SubSceneManager:
SceneManager

@ End

SubSceneManager. m

# Import
"SubSceneManager. h"

@ Implementation SubSceneManager

-(Id) init
{
Self = [super init];
If (self ){
// Initialization code here.
}

Return self;
}

@ End

Main. m
# Import
<Foundation/Foundation. h>
# Import "scenemanager. H"
# Import
"Subscenemanager. H"
Int main (INT argc, const char * argv [])
{

NSAID utoreleasepool * Pool = [[NSAID utoreleasepool alloc] init];

Scenemanager * Sm = [[subscenemanager alloc] init];
[Sm go];

// This sentence should be commented out
/*
[Scenemanager wrap]; // a warning is reported: Class Method of "+ wrap" not found.
// Although it is a warning, it is normal to run, but it is not well written in self-standardization. Even if the compiler does not impose any restrictions, we have to limit ourselves.
// Otherwise, the extension method is meaningless.
*/
[Pool drain];
Return 0;
}

Certificate -----------------------------------------------------------------------------------------------------------------------------------------------------------
Although the call cannot be forcibly restricted, is it a good coding habit? I understand this.