Objective-c the Protocol

Objective-c the Protocol

Protocol

In a nutshell, a list of methods that are declared can be implemented by whatever class, usually called (delegation) mode.

In iOS and OS X, Apple uses a number of proxy modes to implement view (UI controls) and controller (controllers) in MVC

Here's a sample example

Declares a button class and a Buttonlisterner class

In the Button.h file

#import <foundation/foundation.h>//class declaration @class button;//<> represents the implementation of a protocol, nsobject to make a fundamental agreement// Buttondelegate is the name of the protocol @protocol buttondelegate<nsobject>-(void) OnClick: (button*) but; @end @interface Button: Nsobject//nonatomic does not require multi-threading management, delegate is a button listener @property (nonatomic,retain) id<buttondelegate> delegate;-( void) Click; @end

In the button.m file

#import "Button.h" @implementation button//-(void) dealloc{//    [Super dealloc];//}-(void) click{    NSLog (@ " Clickbutton was clicked ...
");        Suppose there is an OnClick: The method calls this method    if ([_delegate respondstoselector: @selector (OnClick:)]) {        //and tells the Listener which button was clicked        [_delegate onclick:self];    }    } @end

In the Buttonlisterner.h file

#import <Foundation/Foundation.h> #import "Button.h"//advance notice of the agreement. The role of @class is the same as the @protocol buttondelegate; @interface buttonlisterner:nsobject<buttondelegate> @end

In the buttonlisterner.m file

#import "Buttonlisterner.h" #import "Button.h" @implementation buttonlisterner-(void) OnClick: (Button *) but{    NSLog (@ "OnClick ..."); @end

in the main.m

int main (int argc, const char * argv[]) {    @autoreleasepool {        button* button = [[button alloc]init];        buttonlisterner* listenter = [[Buttonlisterner alloc]init];        Button.delegate=listenter;        [Button Click];                }    return 0;}

Objective-c the Protocol