Creating A Delegate Callback

Often you need a class to call back a method of its owner. In this example MainClass is the class that needs to be called back and SubClass is the class that will need to call back a method in the MainClass. 


//You can copy the entire block below and then use find and replace on the following to make it ready for use in your application:
//MySubClassName            Sub class name within the main class
//mySubClass1               Sub class object within the main class
//MethodNameToCallBack      Main class method to be called back
//SubClassDelegate          Delegate name
In MainClass.h

//Include the sub class header:
#import "MySubClassName.h"

//Add the delegate as an input to the class
@interface MainClassViewController : UIViewController
	<SubClassDelegate>
{
	MySubClassName *mySubClass1;
In MainClass.m

//When the create the sub class:
	mySubClass1 = [[MySubClassName alloc] init];
	[mySubClass1 setDelegate:self];

//The method that will be called back:
- (void)MethodNameToCallBack:(NSString *)s
{
	NSLog(s);
}

//********** DEALLOC **********
- (void)dealloc
{
	[mySubClass1 release];
In SubClass.h

#import <Foundation/Foundation.h>

//Define the protocol for the delegate
@protocol SubClassDelegate
- (void)MethodNameToCallBack:(NSString *)s;
@end

@interface MySubClassName : NSObject
{
}
@property (nonatomic, assign) id  <SubClassDelegate> delegate;  

@end
In SubClass.m

@implementation MySubClassName
//Synthesize the delegate property:
@synthesize delegate;

//When you want to callback the MainClass method:
	[[self delegate] MethodNameToCallBack:@"Hello World"];

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