让我们从一个例子开始，如果我们在网上购买一件产品，它会经过不同团队处理的运输/交付等流程。因此，如果运输完成，运输团队应该通知交付团队，并且应该是一对一的沟通，因为广播这个信息对其他人来说是一种开销/供应商可能只希望将这个信息传递给需要的人。

所以如果我们从应用的角度考虑，一个事件可以是一个在线订单，不同的团队可以是多个视图。

下面是代码，将ShippingView作为发货团队，将DeliveryView作为交付团队:

//Declare the protocol with functions having info which needs to be communicated
protocol ShippingDelegate : class {
    func productShipped(productID : String)
}
//shippingView which shows shipping status of products
class ShippingView : UIView
{

    weak var delegate:ShippingDelegate?
    var productID : String

    @IBAction func checkShippingStatus(sender: UIButton)
    {
        // if product is shipped
        delegate?.productShipped(productID: productID)
    }
}
//Delivery view which shows delivery status & tracking info
class DeliveryView: UIView,ShippingDelegate
{
    func productShipped(productID : String)
    {
        // update status on view & perform delivery
    }
}

//Main page on app which has both views & shows updated info on product whole status
class ProductViewController : UIViewController
{
    var shippingView : ShippingView
    var deliveryView : DeliveryView

    override func viewDidLoad() {
        super.viewDidLoad()
        // as we want to update shipping info on delivery view, so assign delegate to delivery object
        // whenever shipping status gets updated it will call productShipped method in DeliveryView & update UI.
        shippingView.delegate = deliveryView
        //
    }
}

拜托!查看下面的简单一步一步的教程，了解委托如何在iOS中工作。

iOS中的委托

我已经创建了两个viewcontroller(用于从一个视图控制器发送数据到另一个视图控制器)

FirstViewController实现委托(提供数据)。 SecondViewController声明委托(它将接收数据)。

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!");
}

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{
}

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];

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.