AFNetworking是一个轻量级的iOS网络通信类库，继ASI类库不在更新之后开发者们有一套不错选择；
AFNetworking类库源码下载和使用教程: https://github.com/AFNetworking/AFNetworking
如果想深入研究有官方文档介绍:http://afnetworking.github.com/AFNetworking/
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在开源中国iOS客户端中关于AFNetworking类库的使用只用到了两个实例方法
(1)getPath:parameters:success:failure:
(2)postPath:parameters:success:failure:
他们用法基本相同，只是请求数据方式不同，一种是Get请求和Post请求。Get是向服务器发索取数据的一种请求，也就相当于查询信息功能，不会修改类容，Post是向服务器提交数据的一种请求，影响数据内容；两种方法定义：
- (void)getPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure { NSURLRequest *request = [self requestWithMethod:@"GET" path:path parameters:parameters]; AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure]; [self enqueueHTTPRequestOperation:operation]; }
- (void)postPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure { NSURLRequest *request = [self requestWithMethod:@"POST" path:path parameters:parameters]; AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure]; [self enqueueHTTPRequestOperation:operation]; }
getPath:parameters:success:failure:方法在程序中使用举例:
NewsView.m
- (void)reload:(BOOL)noRefresh { //如果有网络连接 if ([Config Instance].isNetworkRunning) { if (isLoading || isLoadOver) { return; } if (!noRefresh) { allCount = 0; } int pageIndex = allCount/20; NSString *url; switch (self.catalog) { case 1: url = [NSString stringWithFormat:@"%@?catalog=%d&pageIndex=%d&pageSize=%d", api_news_list, 1, pageIndex, 20]; break; case 2: url = [NSString stringWithFormat:@"%@?type=latest&pageIndex=%d&pageSize=%d", api_blog_list, pageIndex, 20]; break; case 3: url = [NSString stringWithFormat:@"%@?type=recommend&pageIndex=%d&pageSize=%d", api_blog_list, pageIndex, 20]; break; } [[AFOSCClient sharedClient]getPath:url parameters:Nil success:^(AFHTTPRequestOperation *operation, id responseObject) { [Tool getOSCNotice2:operation.responseString]; isLoading = NO; if (!noRefresh) { [self clear]; } @try { NSMutableArray *newNews = self.catalog <= 1 ? [Tool readStrNewsArray:operation.responseString andOld: news]: [Tool readStrUserBlogsArray:operation.responseString andOld: news]; int count = [Tool isListOver2:operation.responseString]; allCount += count; if (count < 20) { isLoadOver = YES; } [news addObjectsFromArray:newNews]; [self.tableNews reloadData]; [self doneLoadingTableViewData]; //如果是第一页 则缓存下来 if (news.count <= 20) { [Tool saveCache:5 andID:self.catalog andString:operation.responseString]; } } @catch (NSException *exception) { [NdUncaughtExceptionHandler TakeException:exception]; } @finally { [self doneLoadingTableViewData]; } } failure:^(AFHTTPRequestOperation *operation, NSError *error) { NSLog(@"新闻列表获取出错"); //如果是刷新 [self doneLoadingTableViewData]; if ([Config Instance].isNetworkRunning == NO) { return; } isLoading = NO; if ([Config Instance].isNetworkRunning) { [Tool ToastNotification:@"错误 网络无连接" andView:self.view andLoading:NO andIsBottom:NO]; } }]; isLoading = YES; [self.tableNews reloadData]; } //如果没有网络连接 else { NSString *value = [Tool getCache:5 andID:self.catalog]; if (value) { NSMutableArray *newNews = [Tool readStrNewsArray:value andOld:news]; [self.tableNews reloadData]; isLoadOver = YES; [news addObjectsFromArray:newNews]; [self.tableNews reloadData]; [self doneLoadingTableViewData]; } } }
分析一下这里面的代码：
首先是做一个网络连接判断，在开源中国iOS客户端学习——(六)网络连接检测一文中介绍了，作者并不是用这种方法来判断，而是使用getPath:parameters:success:failure:来判断网络的连接，方法使用AFHTTPRequestOperation和“PATCH”请求HTTP客户端操作队列，使用到了block块(iOS 4.0+特性)，URL请求成功执行success块里操作，这里面block块没有返回值，接受两个参数，创建请求操作和响应数据请求，URL请求失败执行failure里面的方法，这个block块里仍没有返回值，接受两个参数创建请求操作和NSError对象，描述网络或解析错误状况；
在 if()中的方法[Config Instance].isNetworkRunning==YES的,如果程序加载或者已经加载完毕什么也不返回，如果程序没有加载数据，将数据列表数量显示为0，接下来是在switch()中，根据使用者选择设置不同API接口(下图)，然后就是解析显示数据信息，显示在视图中；
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在AFNetwork 文件夹中，作者自己添加了一个AFOSCClient类，该类继承AFHTTPClient，又设计了一个sharedClient的类方法，从返回的结果可以推测出它是通过API请求返回json类型的数据，具体什么作用还没看出来；
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[Tool getOSCNotice2:operation.responseString];是封装在在Tool类中的解析获取的XML的文件
URL请求成功，还做了一个程序异常处理，防止请求数据过成功程序异常崩溃
关于@try @catch @finally异常处理的使用：
@try
{
//执行的代码，其中可能有异常。一旦发现异常，则立即跳到catch执行。否则不会执行catch里面的内容
}
@catch
{
//除非try里面执行代码发生了异常，否则这里的代码不会执行
}
@finally
{
//不管什么情况都会执行，包括try catch 里面用了return ,可以理解为只要执行了try或者catch，就一定会执行 finally
}
如果URL请求的数据出错，则反应网络不连通，数据不能加载，则弹出GCDiscreetNotificationView提示视图 提示网络错误；
postPath:parameters:success:failure:方法在程序中使用举例:
FriendsView.m
-(void)reload:(BOOL)noRefresh { if (isLoadOver) { [self doneLoadingTableViewData]; return; } [[AFOSCClient sharedClient] postPath:api_friends_list parameters:[NSDictionary dictionaryWithObjectsAndKeys:segement.selectedSegmentIndex == 0 ? @"1" : @"0",@"relation", [NSString stringWithFormat:@"%d", friends.count/20],@"pageIndex", @"20",@"pageSize", [NSString stringWithFormat:@"%d", [Config Instance].getUID],@"uid",nil] success:^(AFHTTPRequestOperation *operation, id responseObject) { if (!noRefresh) { [self clear]; } [self doneLoadingTableViewData]; isLoading = NO; NSString *response = operation.responseString; [Tool getOSCNotice2:response]; @try { TBXML *xml = [[TBXML alloc] initWithXMLString:response error:nil]; TBXMLElement *root = xml.rootXMLElement; //显示 TBXMLElement *_friends = [TBXML childElementNamed:@"friends" parentElement:root]; if (!_friends) { isLoadOver = YES; [self.tableFriends reloadData]; return; } TBXMLElement *first = [TBXML childElementNamed:@"friend" parentElement:_friends]; if (first == nil) { [self.tableFriends reloadData]; isLoadOver = YES; return; } NSMutableArray *newFriends = [[NSMutableArray alloc] initWithCapacity:20]; TBXMLElement *name = [TBXML childElementNamed:@"name" parentElement:first]; TBXMLElement *userid = [TBXML childElementNamed:@"userid" parentElement:first]; TBXMLElement *portrait = [TBXML childElementNamed:@"portrait" parentElement:first]; TBXMLElement *expertise = [TBXML childElementNamed:@"expertise" parentElement:first]; TBXMLElement *gender = [TBXML childElementNamed:@"gender" parentElement:first]; Friend *f = [[Friend alloc] initWithParameters:[TBXML textForElement:name] andUID:[[TBXML textForElement:userid] intValue] andPortrait:[TBXML textForElement:portrait] andExpertise:[TBXML textForElement:expertise] andMale:[[TBXML textForElement:gender] intValue] == 1]; if (![Tool isRepeatFriend: friends andFriend:f]) { [newFriends addObject:f]; } while (first) { first = [TBXML nextSiblingNamed:@"friend" searchFromElement:first]; if (first) { name = [TBXML childElementNamed:@"name" parentElement:first]; userid = [TBXML childElementNamed:@"userid" parentElement:first]; portrait = [TBXML childElementNamed:@"portrait" parentElement:first]; expertise = [TBXML childElementNamed:@"expertise" parentElement:first]; gender = [TBXML childElementNamed:@"gender" parentElement:first]; f = [[Friend alloc] initWithParameters:[TBXML textForElement:name] andUID:[[TBXML textForElement:userid] intValue] andPortrait:[TBXML textForElement:portrait] andExpertise:[TBXML textForElement:expertise] andMale:[[TBXML textForElement:gender] intValue] == 1]; if (![Tool isRepeatFriend:friends andFriend:f]) { [newFriends addObject:f]; } } else break; } if (newFriends.count < 20) { isLoadOver = YES; } [friends addObjectsFromArray:newFriends]; [self.tableFriends reloadData]; } @catch (NSException *exception) { [NdUncaughtExceptionHandler TakeException:exception]; } @finally { [self doneLoadingTableViewData]; } } failure:^(AFHTTPRequestOperation *operation, NSError *error) { NSLog(@"好友列表获取出错"); [self doneLoadingTableViewData]; isLoading = NO; if ([Config Instance].isNetworkRunning) { [Tool ToastNotification:@"错误 网络无连接" andView:self.view andLoading:NO andIsBottom:NO]; } }]; isLoading = YES; [self.tableFriends reloadData]; }
这个方法和getPath:parameters:success:failure:不同的在于请求方式是POST请求，可以向服务器里提交数据；
本文转自新风作浪 51CTO博客，原文链接：http://blog.51cto.com/duxinfeng/1208682
，如需转载请自行联系原作者
