oc中的blocks的功能,一种比代理简洁的方式

blocks方式:

谁要东西谁就要写blocks,通过blocks(返回值)获取想要的,提供东西的人要通过实现函数指针把东西给想要的人.当然也可以传值,传值需要通过形参.

block的功能:

block功能就是通过一个方法的返回值来获取其他类中的内容,或者设置其他类中的值, 总的来说就是操作其他类,其他类调用block时,可以具有一些灵活性,但是必须符合方法规范(即block定义的方法的形式).

上面是个人对blocks的理解;接下来是自己写的一个简单的例子模拟,卖方-快递-买方,之间的交互,大体结构是:卖方通过blocks将货物交给快递,快递将货物送到客户手中客户将钱给快递员.

/**********************************************************************************************/

/**********************************************************************************************/

首先是main.m文件

//买方向卖方提交商品信息

Buyer *buyer1=[[Buyer alloc] init];

[buyer1 setGoods:@"apple1"];

[buyer1 setName:@"buyer1"];

Buyer *buyer2=[[Buyer alloc] init];

[buyer2 setGoods:@"apple2"];

[buyer2 setName:@"buyer2"];

Buyer *buyer3=[[Buyer alloc] init];

[buyer3 setGoods:@"apple3"];

[buyer3 setName:@"buyer3"];

Buyer *buyer4=[[Buyer alloc] init];

[buyer4 setGoods:@"apple4"];

[buyer4 setName:@"buyer4"];

NSArray *arrGoods=@[[buyer1 goods],[buyer2 goods],[buyer3 goods],[buyer4 goods]];

//买方规定价钱

Seller *seller=[[Seller alloc] init];

[seller setGoods:[buyer1 goods]];

[seller setBuyerName:[buyer1 name]];

[seller setMoney:@"12"];

[seller setGoods:[buyer2 goods]];

[seller setBuyerName:[buyer2 name]];

[seller setMoney:@"34"];

[seller setGoods:[buyer3 goods]];

[seller setBuyerName:[buyer3 name]];

[seller setMoney:@"135"];

[seller setGoods:[buyer4 goods]];

[seller setBuyerName:[buyer4 name]];

[seller setMoney:@"543"];

//将价格和商品存入数组发送给快递

NSArray *arrBuyer=[[NSArray alloc] initWithArray:[seller buyerName]];

NSArray *arrMoney=[[NSArray alloc] initWithArray:[seller money]];

Poster *poster=[[Poster alloc] init];

[poster setBuyerList:arrBuyer];

[poster setGoodsList:arrGoods];

[poster setGoodsMoney:arrMoney];

[seller setSeller:poster];

//快递把商品交给买方

[poster setPoster:buyer1];

sleep(1);

[poster setPoster:buyer2];

sleep(1);

[poster setPoster:buyer3];

sleep(1);

[poster setPoster:buyer4];

sleep(1);

接下来是各个类的具体实现:

/**********************************************************************************************/

Seller.h

/**********************************************************************************************/

#import <Foundation/Foundation.h>

#import "Poster.h"

@interface Seller : NSObject

{

Poster *_poster;

NSMutableArray *_buyername;    //保存买方的姓名

NSMutableArray *_goods;           //保存买方的商品

NSMutableArray *_money;          //保存买方的商品价格

}

-(void)setBuyerName:(NSString *)name;

-(NSMutableArray *)buyerName;

-(void)setGoods:(NSString *)goods1;

-(NSMutableArray *)goods;

-(void)setMoney:(NSString *)money1;

-(NSMutableArray *)money;

-(void)setSeller:(Poster *)poster;      //回调方法,将送货单(姓名,商品,价格)传给快递

@end

/**********************************************************************************************/

Seller.m

/**********************************************************************************************/

#import "Seller.h"

@implementation Seller

-(id)init

{

if(self=[super init])

{

_buyername = [[NSMutableArray alloc] init];

_goods=[[NSMutableArray alloc] init];

_money=[[NSMutableArray alloc] init];

}

return self;

}

-(void)setBuyerName:(NSString *)name

{

[_buyername addObject:name];

}

-(NSMutableArray *)buyerName

{

return _buyername;

}

-(void)setGoods:(NSString *)goods1

{

[_goods addObject:goods1];

}

-(NSMutableArray *)goods

{

return _goods;

}

-(void)setMoney:(NSString *)money1

{

[_money addObject:money1];

}

-(NSMutableArray *)money

{

return _money;

}

//调用Poster中的方法,让poster回调Seller获取要送的东西(包含价格和商品,还有顾客信息)

-(void)setSeller:(Poster *)poster

{

[poster sendGoods:^NSMutableArray *(void) {

NSMutableArray *dic=[[NSMutableArray alloc] init];

[dic addObject:_buyername];

[dic addObject:_goods];

[dic addObject:_money];

NSLog(@"\n卖家把货单给了快递\n货单如下:");

NSMutableString *ms=[[NSMutableString alloc] init];

for(int i=0;i<[[dic objectAtIndex:0] count];i++)

{

[ms appendFormat:@"\n"];

for(int j=0;j<[dic count];j++)

{

[ms appendFormat:@"%@ ",[[dic objectAtIndex:j] objectAtIndex:i]];

}

}

NSLog(@"%@",ms);

return dic;

}];

}

@end

/**********************************************************************************************/

Poster.h

/**********************************************************************************************/

#import <Foundation/Foundation.h>

#import "Buyer.h"

@interface Poster : NSObject

{

Buyer *_buyer;

NSMutableArray *_buyerList;    //保存买方的姓名

NSMutableArray *_goodsList;    //保存买方的商品

NSMutableArray *_goodsMoney;   //保存买方的商品价格

}

-(void)setBuyerList:(NSArray *)buyerList;

-(NSMutableArray *)buyList;

-(void)setGoodsList:(NSArray *)goods;

-(NSMutableArray *)goodsList;

-(void)setGoodsMoney:(NSArray *)money;

-(NSMutableArray *)goodsMoney;

-(void)sendGoods:(NSMutableArray *(^)(void))eachSend;    //建立blocks,供外界访问

-(void)setPoster:(Buyer *)buyer;    //回调方法,传送商品和价格信息

@end

/**********************************************************************************************/

Poster.m

/**********************************************************************************************/

#import "Poster.h"

@implementation Poster

-(id)init

{

if(self =[super init])

{

_goodsList=[[NSMutableArray alloc] init];

_goodsMoney=[[NSMutableArray alloc] init];

}

return self;

}

-(void)setBuyerList:(NSMutableArray *)buyerList

{

_buyerList=buyerList;

}

-(NSMutableArray *)buyList

{

return _buyerList;

}

-(void)setGoodsList:(NSMutableArray *)goods

{

_goodsList = goods;

}

-(NSMutableArray *)goodsList

{

return _goodsList;

}

-(void)setGoodsMoney:(NSMutableArray *)money

{

_goodsMoney = money;

}

-(NSMutableArray *)goodsMoney

{

return _goodsMoney;

}

//调用buyer中的方法,让buyer回调poster获取要给的钱数

-(void)setPoster:(Buyer *)buyer

{

static int i=-1;

_buyer = buyer;

[buyer reciveGoods:^NSString *(void) {

i++;

return [[NSString alloc]initWithFormat:@"%@ %@",[_goodsMoney objectAtIndex:i],[_goodsList objectAtIndex:i]];

}];

}

//回调Seller类中获取货物发送给顾客

-(void)sendGoods:(NSMutableArray *(^)(void))eachSend

{

NSMutableArray *mArr=[[NSMutableArray alloc]initWithArray:eachSend()];

NSArray *buyerArray=[mArr objectAtIndex:0];

NSArray *goodsArray=[mArr objectAtIndex:1];

NSArray *moneyArray=[mArr objectAtIndex:2];

_buyerList=[[NSMutableArray alloc] initWithArray: buyerArray];

_goodsMoney=[[NSMutableArray alloc] initWithArray: moneyArray];

_goodsList=[[NSMutableArray alloc] initWithArray:goodsArray];

//    //postBlocks=[afterEachSend copy];

for(int i=0;i<[[mArr objectAtIndex:1] count];i++)

{

NSLog(@"货物%@已经发出.",[goodsArray objectAtIndex:i]);  //快递发送完商品后返回商品名给商家

sleep(1);

}

}

@end

Buyer.h

#import <Foundation/Foundation.h>

@interface Buyer : NSObject

@property (nonatomic,copy) NSString *name;                     //保存用户姓名

@property (nonatomic,copy) NSString *goods;                     //保存购买的商品

-(void)reciveGoods:(NSString *(^)(void))afterEachRecive;    //建立blocks,供外界访问

@end

/**********************************************************************************************/

Buyer.m

/**********************************************************************************************/

#import "Buyer.h"

@implementation Buyer

-(id)init

{

if(self=[super init])

{

_name=@"";

_goods=@"";

}

return self;

}

//Buyer回调Poster获取要给的钱数

-(void)reciveGoods:(NSString *(^)(void))afterEachRecive

{

NSArray *arr=[afterEachRecive() componentsSeparatedByString:@" "];

NSLog(@"%@收到商品后,为%@支付了%@",[self name], arr[1], arr[0]);//买家接收商品后返回钱

}

@end

/**********************************************************************************************/

代码运行结果

/**********************************************************************************************/

2015-08-16 21:19:46.276 Asignment_1[758:24272]

卖家把货单给了快递

货单如下:

2015-08-16 21:19:46.316 Asignment_1[758:24272]

buyer1 apple1 12

buyer2 apple2 34

buyer3 apple3 135

buyer4 apple4 543

2015-08-16 21:19:46.316 Asignment_1[758:24272] 货物apple1已经发出.

2015-08-16 21:19:47.321 Asignment_1[758:24272] 货物apple2已经发出.

2015-08-16 21:19:48.324 Asignment_1[758:24272] 货物apple3已经发出.

2015-08-16 21:19:49.327 Asignment_1[758:24272] 货物apple4已经发出.

2015-08-16 21:19:50.333 Asignment_1[758:24272] buyer1收到商品后,为apple1支付了12

2015-08-16 21:19:51.334 Asignment_1[758:24272] buyer2收到商品后,为apple2支付了34

2015-08-16 21:19:52.340 Asignment_1[758:24272] buyer3收到商品后,为apple3支付了135

2015-08-16 21:19:53.341 Asignment_1[758:24272] buyer4收到商品后,为apple4支付了543