第八讲：Obj-C 协议 Delegate 代理设计模式

第八讲：Obj-C 协议 Delegate 代理设计模式

//  Dog.h
#import <Foundation/Foundation.h>
@protocol DogBark; // 这里声明后边的 DogBark 协议
// @protocol 表示协议前向声明
// @class Dog;  也可以，把后面的 DogBark 协议放到前边，声明 Dog
// @class 表示前向声明一个类
@interface Dog : NSObject
{
int _ID;
NSTimer *timer;  // 定时器
int barkCount; // 叫的次数
id <DogBark> delegate; //ownner 存狗的主人
}
@property int ID;
@property (assign) id <DogBark> delegate;

@end

// 定义一个人和狗通讯的方式 protocol
@protocol DogBark <NSObject>

- (void) bark:(Dog *)thisDog count:(int)count;

@end

//  Dog.m
#import "Dog.h"
#import "Person.h"

@implementation Dog
@synthesize ID = _ID;
@synthesize delegate;
- (id) init
{
self = [super init];
if (self)
{
timer = [NSTimer scheduledTimerWithTimeInterval:1.0f
target:self
selector:@selector(updateTimer:)
userInfo:nil
repeats:YES];
// 创建一个定时器 每隔 1.0s 就调用 ［self updateTimer:nil］;
}
return self;
}

- (void) updateTimer:(id)arg
{
barkCount++;
NSLog(@"dog bark %d", barkCount);
// 通知狗的主人  就是 delegate
[delegate bark:self count:barkCount];
// 调用 delegate 主人里面的 bark:count: 方法
// 向主人回报
}
@end

//  Person.h
#import <Foundation/Foundation.h>
#import "Dog.h"

@interface Person : NSObject <DogBark>
{
Dog *_dog;
}
@property (retain) Dog *dog;
@end

//  Person.m
#import "Person.h"
@implementation Person
@synthesize dog = _dog;

- (void) setDog:(Dog *)dog
{
if (_dog != dog) {
[_dog release];
_dog = [dog retain];
// 通知 _dog 的主人是 self
[_dog setDelegate:self];
}
}
- (Dog *) dog
{
return _dog;
}
- (void) bark:(Dog *)thisDog count:(int)count
{
// 当狗叫的时候来调用 xiaoLi 人的这个方法
NSLog(@"Person this dog %d bark %d", [thisDog ID], count);
}
- (void) dealloc
{
self.dog = nil;
[super dealloc];
}
@end

//  main.m
#import <Foundation/Foundation.h>
#import "Dog.h"
#import "Person.h"

int main (int argc, const char * argv[])
{
@autoreleasepool
{
NSLog(@"Hello, World!");
Person *xiaoLi = [[Person alloc] init];
Dog *dog = [[Dog alloc] init];
[dog setID:10];

[xiaoLi setDog:dog];
[dog release];

while (1)
{
[[NSRunLoop currentRunLoop] run];
}

[xiaoLi release];
}
return 0;
}
/* 输出结果
2012-12-17 21:45:18.909  Hello, World!
2012-12-17 21:45:19.913  dog bark 1
2012-12-17 21:45:19.914  Person this dog 10 bark 1
2012-12-17 21:45:20.920  dog bark 2
2012-12-17 21:45:20.923  Person this dog 10 bark 2
2012-12-17 21:45:21.912  dog bark 3
2012-12-17 21:45:21.913  Person this dog 10 bark 3
2012-12-17 21:45:22.912  dog bark 4
2012-12-17 21:45:22.913  Person this dog 10 bark 4
2012-12-17 21:45:23.913  dog bark 5
2012-12-17 21:45:23.914  Person this dog 10 bark 5
2012-12-17 21:45:24.913  dog bark 6
2012-12-17 21:45:24.914  Person this dog 10 bark 6
2012-12-17 21:45:25.913  dog bark 7
2012-12-17 21:45:25.914  Person this dog 10 bark 7
...........................................
.......................
...............
*/