下面是一个创建委托的简单方法

在.h文件中创建协议。确保它是在协议之前定义的，使用@class后面跟着UIViewController的名字，因为我要使用的协议是UIViewController类>。

步骤:1:创建一个名为“YourViewController”的新类Protocol，它将是UIViewController类的子类，并将这个类分配给第二个ViewController。

步骤2:转到“YourViewController”文件，并如下所示修改它:

#import <UIKit/UIkit.h>
@class YourViewController;

@protocol YourViewController Delegate <NSObject>

 @optional
-(void)defineDelegateMethodName: (YourViewController *) controller;

@required
-(BOOL)delegateMethodReturningBool: (YourViewController *) controller;

  @end
  @interface YourViewController : UIViewController

  //Since the property for the protocol could be of any class, then it will be marked as a type of id.

  @property (nonatomic, weak) id< YourViewController Delegate> delegate;

@end

协议行为中定义的方法可以用@optional和@required作为协议定义的一部分进行控制。

步骤3: 委托的实现

    #import "delegate.h"

   @interface YourDelegateUser ()
     <YourViewControllerDelegate>
   @end

   @implementation YourDelegateUser

   - (void) variousFoo {
      YourViewController *controller = [[YourViewController alloc] init];
      controller.delegate = self;
   }

   -(void)defineDelegateMethodName: (YourViewController *) controller {
      // handle the delegate being called here
   }

   -(BOOL)delegateMethodReturningBool: (YourViewController *) controller {
      // handle the delegate being called here
      return YES;
   }

   @end

//在调用该方法之前测试该方法是否已经定义

 - (void) someMethodToCallDelegate {
     if ([[self delegate] respondsToSelector:@selector(defineDelegateMethodName:)]) {
           [self.delegate delegateMethodName:self]; 
     }
  }

ViewController。h

@protocol NameDelegate <NSObject>

-(void)delegateMEthod: (ArgType) arg;

@end

@property id <NameDelegate> delegate;

ViewController。m

[self.delegate delegateMEthod: argument];

MainViewController.m

ViewController viewController = [ViewController new];
viewController.delegate = self;

方法:

-(void)delegateMEthod: (ArgType) arg{
}

认可的答案很好，但如果你想要一个1分钟的答案，试试这个:

MyClass.h文件应该如下所示(添加带有注释的委托行!)

#import <BlaClass/BlaClass.h>

@class MyClass;             //define class, so protocol can see MyClass
@protocol MyClassDelegate <NSObject>   //define delegate protocol
    - (void) myClassDelegateMethod: (MyClass *) sender;  //define delegate method to be implemented within another class
@end //end protocol

@interface MyClass : NSObject {
}
@property (nonatomic, weak) id <MyClassDelegate> delegate; //define MyClassDelegate as delegate

@end

MyClass。M文件应该是这样的

#import "MyClass.h"
@implementation MyClass 
@synthesize delegate; //synthesise  MyClassDelegate delegate

- (void) myMethodToDoStuff {
    [self.delegate myClassDelegateMethod:self]; //this will call the method implemented in your other class    
}

@end

要在另一个类中使用你的委托(UIViewController在这种情况下称为MyVC) MyVC.h:

#import "MyClass.h"
@interface MyVC:UIViewController <MyClassDelegate> { //make it a delegate for MyClassDelegate
}

MyVC.m:

myClass.delegate = self;          //set its delegate to self somewhere

实现委托方法

- (void) myClassDelegateMethod: (MyClass *) sender {
    NSLog(@"Delegates are great!");
}

我认为一旦你理解了委托，所有这些答案都很有意义。就我个人而言，我来自C/ c++的土地，在此之前，像Fortran等过程语言，所以这里是我在c++范式中寻找类似类似物的2分钟。

如果我要向c++ /Java程序员解释委托，我会说

什么是委托? 这些是指向另一个类中的类的静态指针。一旦你分配了一个指针，你就可以调用该类中的函数/方法。因此，类的一些函数被“委托”(在c++中，由类对象指针指向的指针)给另一个类。

什么是协议? 从概念上讲，它的作用与你作为委托类分配的类的头文件类似。协议是一种显式的方式，用于定义在类中需要实现哪些方法，而该类的指针被设置为类中的委托。

How can I do something similar in C++? If you tried to do this in C++, you would by defining pointers to classes (objects) in the class definition and then wiring them up to other classes that will provide additional functions as delegates to your base class. But this wiring needs to be maitained within the code and will be clumsy and error prone. Objective C just assumes that programmers are not best at maintaining this decipline and provides compiler restrictions to enforce a clean implementation.

要创建自己的委托，首先需要创建一个协议并声明必要的方法，而不需要实现。然后在你的头类中实现这个协议在你想要实现委托或委托方法的地方。

协议必须声明如下:

@protocol ServiceResponceDelegate <NSObject>

- (void) serviceDidFailWithRequestType:(NSString*)error;
- (void) serviceDidFinishedSucessfully:(NSString*)success;

@end

这是应该在其中执行某些任务的服务类。它展示了如何定义委托以及如何设置委托。在任务完成后的实现类中，调用委托的方法。

@interface ServiceClass : NSObject
{
id <ServiceResponceDelegate> _delegate;
}

- (void) setDelegate:(id)delegate;
- (void) someTask;

@end

@implementation ServiceClass

- (void) setDelegate:(id)delegate
{
_delegate = delegate;
}

- (void) someTask
{
/*

   perform task

*/
if (!success)
{
[_delegate serviceDidFailWithRequestType:@”task failed”];
}
else
{
[_delegate serviceDidFinishedSucessfully:@”task success”];
}
}
@end

这是通过将委托设置为自身来调用服务类的主视图类。协议也是在头类中实现的。

@interface viewController: UIViewController <ServiceResponceDelegate>
{
ServiceClass* _service;
}

- (void) go;

@end

@implementation viewController

//
//some methods
//

- (void) go
{
_service = [[ServiceClass alloc] init];
[_service setDelegate:self];
[_service someTask];
}

就是这样，通过在这个类中实现委托方法，一旦操作/任务完成，控制就会回来。

委托:-创建

@protocol addToCartDelegate <NSObject>

-(void)addToCartAction:(ItemsModel *)itemsModel isAdded:(BOOL)added;

@end

发送并请指定代表查看您正在发送的数据

[self.delegate addToCartAction:itemsModel isAdded:YES];