@interface MyView : UIView

@property (strong, nonatomic) UIButton *myBtn;

@end

#import "MyView.h" 

@implementation MyView
//view的初始化方法
- (id)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self)
  {  //初始化按鈕
    _myBtn = [[UIButton alloc] initWithFrame:CGRectMake(140, 100, 100, 50)];
    _myBtn.backgroundColor = [UIColor redColor];
    //將按鈕添加到自身
    [self addSubview:_myBtn];
  }
  return self;
}

@end

#import <UIKit/UIKit.h>

@interface MyViewController : UIViewController

@end

#import "MyViewController.h"
#import "MyView.h"

@interface MyViewController ()

@property (strong, nonatomic) MyView *myview;

@end

@implementation MyViewController

- (void)loadView
{
  MyView *myView = [[MyView alloc] initWithFrame: [[UIScreen mainScreen] bounds] ];
  self.view = myView;
  self.myview = myView;
  
  //在controller中設(shè)置按鈕的目標-動作，其中目標是self，也就是控制器自身，動作是用目標提供的BtnClick:方法，
  [self.myview.myBtn addTarget:self
             action:@selector(BtnClick:)
        forControlEvents:UIControlEventTouchUpInside];
}

//MyView中的按鈕的事件
- (void)BtnClick:(UIButton *)btn
{
  NSLog(@"Method in controller.");
  NSLog(@"Button clicked.");
}

 #import "AppDelegate.h"
#import "MyViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  
  self.window = [ [UIWindow alloc] initWithFrame: [[UIScreen mainScreen] bounds ] ];
  
  MyViewController *myVC = [[MyViewController alloc] init];
  self.window.rootViewController = myVC;
  
  self.window.backgroundColor = [UIColor whiteColor];
  [self.window makeKeyAndVisible];
          
  return YES;
}

#import <UIKit/UIKit.h>

//自定義的按鈕協(xié)議，該協(xié)議實現(xiàn)了<NSObject>協(xié)議，協(xié)議的名稱自定，不過不要和Apple的協(xié)議重名
@protocol myBtnDelegate <NSObject>

//協(xié)議中的方法，遵循該協(xié)議的類提供其具體的實現(xiàn)，協(xié)議有@optional和@required兩個修飾符，默認情況下是@required
- (void) BtnClick:(UIButton *)btn;

@end

//MyView的接口
@interface MyView : UIView

//聲明一個屬性，這個屬性用于指定誰來成為本類的代理，由于不能確定什么類型的對象會成為本類的代理，因此聲明為id類型
@property (weak, nonatomic) id<myBtnDelegate> delegate;

@end

#import "MyView.h"

@interface MyView ()
//聲明在.m中的按鈕對外部不可見
@property (strong, nonatomic) UIButton *myBtn;

@end

@implementation MyView
//初始化
- (id)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self)
  {
    _myBtn = [[UIButton alloc] initWithFrame:CGRectMake(140, 100, 100, 50)];
    _myBtn.backgroundColor = [UIColor redColor];
    //為按鈕設(shè)置目標-動作，其中目標是self即包含該按鈕的view自身，動作是有目標（view）提供的myBtnClick：方法
    [_myBtn addTarget:self
          action:@selector(myBtnClick:) forControlEvents:UIControlEventTouchUpInside];
    [self addSubview:_myBtn];
  }
  
  return self;
}
//view中按鈕的事件
- (void)myBtnClick:(UIButton *)btn
{
  NSLog(@"Method in view");
  //在回調(diào)代理方法時，首先判斷自身的代理是否實現(xiàn)了代理方法，否則會導致崩潰
  //如果自身代理實現(xiàn)了代理方法，在該方法中回調(diào)代理實現(xiàn)的具體的代理方法
  if ( [self.delegate respondsToSelector:@selector(BtnClick:)] )
  {
    [self.delegate BtnClick: btn];
  }
  else
  {
    NSLog(@"BtnClick: haven't found in delegate.");
  }
  
}

@end

#import "MyViewController.h"
#import "MyView.h"
//聲明該controller遵循 <myBtnDelegate>協(xié)議，因此需要實現(xiàn)協(xié)議中的方法
@interface MyViewController () <myBtnDelegate>
@end

@implementation MyViewController

- (void)loadView
{  //創(chuàng)建MyView類型的myView
  MyView *myView = [[MyView alloc] initWithFrame: [[UIScreen mainScreen] bounds] ];
  //將myView的代理設(shè)置為self，即當前controller自身
  myView.delegate = self;
  //將controller的view指向myView
  self.view = myView;
}

//該方法是代理中的方法，在controller中決定點擊myBtn按鈕后具體要做的事情，但controller并不能直接獲取到myBtn
- (void)BtnClick:(UIButton *)btn
{
  NSLog(@"Method in controller.");
  NSLog(@"Button clicked.");
}