写在前面

分享此实例，希望能帮到一些像我一样的初学者。
代码有哪些不好的地方，还望各位读者多多指教。
源码请戳这

头文件 JDNetworkRequest.h

#import <Foundation/Foundation.h>

@protocol JDNetworkRequestDatasource <NSObject>

- (NSString *)jdNetworkRequestBaseURLString; //用于初始化的网址

@end

//网络请求类型
typedef NS_ENUM(NSUInteger,JDNetworkRequestType) {
    JDNetworkRequestTypePost,
    JDNetworkRequestTypeGet,
    JDNetworkRequestTypeHead,
    JDNetworkRequestTypePut,
    JDNetworkRequestTypeDelete
};

typedef void(^JDNetworkRequestResultBlock)(id responseObject,NSError *error);

@interface JDNetworkRequest : NSObject

@property (nonatomic, weak) id<JDNetworkRequestDatasource> datasource;

/**
 *  发送网络请求
 *
 *  @param urlString   网址字符串
 *  @param parameters  参数
 *  @param type        请求类型
 *  @param resultBlock 返回结果：responseObject,error
 */
- (void)jd_requestWithURLString:(NSString *)urlString
                     parameters:(NSDictionary *)parameters
                           type:(JDNetworkRequestType)type
                    resultBlock:(JDNetworkRequestResultBlock)resultBlock;
@end

实现文件 JDNetworkRequest.m

类扩展部分

@interface JDNetworkRequest ()
@property (nonatomic, strong) AFHTTPSessionManager *manager;
@property (nonatomic, assign, getter=isConnected) BOOL connected;     /**<网络是否连接*/
@end

介绍网络请求方法之前，先介绍几个会用到的方法

• 判断网络是否连接的方法

- (BOOL)isConnected {
    struct sockaddr zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sa_len = sizeof(zeroAddress);
    zeroAddress.sa_family = AF_INET;

    SCNetworkReachabilityRef defaultRouteReachability =
    SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
    SCNetworkReachabilityFlags flags;

    BOOL didRetrieveFlags =
    SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
    CFRelease(defaultRouteReachability);

    if (!didRetrieveFlags) {
        printf("Error. Count not recover network reachability flags\n");
        return NO;
    }
    
    BOOL isReachable = flags & kSCNetworkFlagsReachable;
    BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
    return (isReachable && !needsConnection) ? YES : NO;
}

• self.manager懒加载

   - (AFHTTPSessionManager *)manager {
      if (!_manager) {
          NSString *baseUrlString = [self.datasource jdNetworkRequestBaseURLString];
          _manager = [[AFHTTPSessionManager alloc]
                      initWithBaseURL:[NSURL URLWithString:baseUrlString]];
       }
       return _manager;
   }
  

• 统一处理返回参数的方法

  - (void)handleRequestResultWithDataTask:(NSURLSessionDataTask *)task
                           responseObject:(id)responseObject
                                    error:(NSError *)error
                              resultBlock:(JDNetworkRequestResultBlock)resultBlock {
                                //do something here...
                                JD_EXECUTE_BLOCK(resultBlock,responseObject,error);
                                }

网络请求方法的具体实现如下：

@implementation JDNetworkRequest

- (void)jd_requestWithURLString:(NSString *)urlString
                     parameters:(NSDictionary *)parameters
                           type:(JDNetworkRequestType)type
                    resultBlock:(JDNetworkRequestResultBlock)resultBlock {
    if (!self.isConnected) {
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"温馨提示"
                                                           message:@"没有网络,建议在手机设置中打开网络"
                                                          delegate:self
                                                 cancelButtonTitle:nil
                                                 otherButtonTitles:@"退出", nil];
        [alertView show];
        return;
    }
    if (![self.datasource respondsToSelector:@selector(jdNetworkRequestBaseURLString)]) {   //未实现datasource
        JDLog(@"error:未实现JDNetworkRequestDatasource");
        return;
    }

    NSSet *acceptableContentTypes = [NSSet setWithObjects:@"application/json",
                                     @"text/html",
                                     @"text/json",
                                     @"text/javascript",
                                     @"text/plain", nil];

    self.manager.operationQueue.maxConcurrentOperationCount = 5;
    self.manager.requestSerializer.timeoutInterval = 3;
    self.manager.responseSerializer.acceptableContentTypes = acceptableContentTypes;

    switch (type) {
        case JDNetworkRequestTypePost: {
            [self.manager POST:urlString
                    parameters:parameters
                       success:^(NSURLSessionDataTask * _Nonnull task, id  _Nonnull responseObject) {
                           [self handleRequestResultWithDataTask:task
                                                  responseObject:responseObject
                                                           error:nil
                                                     resultBlock:resultBlock];
            } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
                [self handleRequestResultWithDataTask:task
                                       responseObject:nil
                                                error:error
                                          resultBlock:resultBlock];
            }];
            break;
     }        
        ...

其他JDNetworkRequestType限于篇幅，就不一一列出，
有兴趣的可以看源码

如何使用？

1. 实现JDNetworkRequestDatasource
   #pragma mark - JDNetworkRequestDatasource

    - (NSString *)jdNetworkRequestBaseURLString {
        //TODO: 网址是无效的，请自行更换
        return @"http://www.example.com";
    }
   

2. 调用网络请求方法
   JDNetworkRequest *networkRequest = [[JDNetworkRequest alloc]init];
   networkRequest.datasource = self;
   //TODO: 以下网址及参数是无效的，请自行更换
   NSString *urlString = @"http://www.example.com/?_c=thread&_a=threadInfo";
   NSDictionary *parameters = @{ @"msg_id" : @0,
   @"sign" : @"149f7fd34ba2a961ab52ac0225da7f6c",
   @"time" : @"1447414060",
   @"token" : @"FMXa++Q0Lwkue+Mdirr6lw==",
   @"thread_id" : @"198"
   };
   [networkRequest jd_requestWithURLString:urlString
   parameters:parameters
   type:JDNetworkRequestTypePost
   resultBlock:^(id responseObject, NSError *error) {
   NSLog(@"%@",responseObject);
   }];

写在最后

欢迎各位读者指教不足之处。