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Anonymous User
Anonymous User 27 Feb 2015 Accepted Answer
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A protocol is a group of related properties and methods that can be implemented by any class.

 

Objective-C allows you to define protocols, which declare the methods expected to be used for a particular situation.

 

Lets understand this with the help of an example

 

// code of AddCountry.h file


#import <Foundation/Foundation.h>
 
// Protocol Name

@protocol AddCountryProtocolDelegate <NSObject>


// protocol method that called after country added in list

@required

- (void) CountryAddedToList;


@end
@interface AddCountry : NSObject


// hold country list.

@property (nonatomic, retain)NSMutableArray* CountryList;


// delegate object
@property (nonatomic,strong) id
<AddCountryProtocolDelegate>delegate;


// method that add country to list
-(void)addCountryToList:(NSString *)object;


@end

 



 
/// Code of AddCountry.m file
#import "AddCountry.h"


@implementation AddCountry
-(void)addCountryToList:(NSString *)object{


    if(_CountryList==nil){



     _CountryList=[[NSMutableArray alloc]init];
 
    }



    [_CountryList
addObject:object];



    [_delegate
CountryAddedToList];



}



@end


// code of view controller.h
#import <UIKit/UIKit.h>
#import "AddCountry.h"


@interface ViewController :
UIViewController<AddCountryProtocolDelegate>
- (IBAction)AddCountryButtonTap:(id)sender;
@property (strong, nonatomic) IBOutlet UITextField *TxtCountry;
@property(strong,nonatomic)AddCountry *CountryObj;
@end


// code of view controller.m
- (void)viewDidLoad {
    [super viewDidLoad];


// initialization of addcountry class  object and setting delegate.
_CountryObj=[[AddCountry alloc]init];



    _CountryObj.delegate=self;
}


- (IBAction)AddCountryButtonTap:(id)sender {
    [_CountryObj
addCountryToList:_TxtCountry.text];
}


 
#pragma mark  add country
class delegate method. this method is called after a country object added to
list.
-(void)CountryAddedToList{
    NSLog(@“Country
added to the list.");
    _TxtCountry.text=nil;
}
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