開源中國iOS客戶端學習——(八)網絡通信AFNetworking類庫

AFNetworking是一個輕量級的iOS網絡通信類庫，繼ASI類庫不在更新之后開發者們有一套不錯選擇；

AFNetworking類庫×××和使用教程: https://github.com/AFNetworking/AFNetworking

如果想深入研究有官方文檔介紹:http://afnetworking.github.com/AFNetworking/

在開源中國iOS客戶端中關于AFNetworking類庫的使用只用到了兩個實例方法

(1)getPath:parameters:success:failure:

(2)postPath:parameters:success:failure:

他們用法基本相同，只是請求數據方式不同，一種是Get請求和Post請求。Get是向服務器發索取數據的一種請求，也就相當于查詢信息功能，不會修改類容，Post是向服務器提交數據的一種請求，影響數據內容；兩種方法定義：

- (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:方法在程序中使用舉例:

NewsView.m

- (void)reload:(BOOL)noRefresh {     //如果有網絡連接     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];                                  //如果是第一頁 則緩存下來                 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(@"新聞列表獲取出錯");             //如果是刷新             [self doneLoadingTableViewData];                          if ([Config Instance].isNetworkRunning == NO) {                 return;             }             isLoading = NO;             if ([Config Instance].isNetworkRunning) {                 [Tool ToastNotification:@"錯誤 網絡無連接" andView:self.view andLoading:NO andIsBottom:NO];             }         }];         isLoading = YES;         [self.tableNews reloadData];     }     //如果沒有網絡連接     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];         }     } } 

分析一下這里面的代碼：

首先是做一個網絡連接判斷，在開源中國iOS客戶端學習——(六)網絡連接檢測一文中介紹了，作者并不是用這種方法來判斷，而是使用getPath:parameters:success:failure:來判斷網絡的連接，方法使用AFHTTPRequestOperation和“PATCH”請求HTTP客戶端操作隊列，使用到了block塊(iOS 4.0+特性)，URL請求成功執行success塊里操作，這里面block塊沒有返回值，接受兩個參數，創建請求操作和響應數據請求，URL請求失敗執行failure里面的方法，這個block塊里仍沒有返回值，接受兩個參數創建請求操作和NSError對象，描述網絡或解析錯誤狀況；

在 if()中的方法[Config Instance].isNetworkRunning==YES的,如果程序加載或者已經加載完畢什么也不返回，如果程序沒有加載數據，將數據列表數量顯示為0，接下來是在switch()中，根據使用者選擇設置不同API接口(下圖)，然后就是解析顯示數據信息，顯示在視圖中；

在AFNetwork 文件夾中，作者自己添加了一個AFOSCClient類，該類繼承AFHTTPClient，又設計了一個sharedClient的類方法，從返回的結果可以推測出它是通過API請求返回json類型的數據，具體什么作用還沒看出來；

[Tool getOSCNotice2:operation.responseString];是封裝在在Tool類中的解析獲取的XML的文件

URL請求成功，還做了一個程序異常處理，防止請求數據過成功程序異常崩潰

 關于@try @catch @finally異常處理的使用：

如果URL請求的數據出錯，則反應網絡不連通，數據不能加載，則彈出GCDiscreetNotificationView提示視圖  提示網絡錯誤；

postPath:parameters:success:failure:方法在程序中使用舉例:

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;                     //顯示                     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(@"好友列表獲取出錯");                                  [self doneLoadingTableViewData];                 isLoading = NO;                 if ([Config Instance].isNetworkRunning) {                     [Tool ToastNotification:@"錯誤 網絡無連接" andView:self.view andLoading:NO andIsBottom:NO];                 }                              }];          isLoading = YES;     [self.tableFriends reloadData]; }