////  HttpRequest.h//  UseBlockCallBack////  Created by Michael on 2/13/14.//  Copyright (c) 2014 EIMS. All rights reserved.//#import <Foundation/Foundation.h>typedef void (^FinishBlock)(NSString *dataString);@interface HttpRequest : NSObject<NSURLConnectionDataDelegate>@property (strong, nonatomic) NSMutableData *resultData;@property (strong, nonatomic) FinishBlock finishBlock;+ (void)postRequestWithURL:(NSString *)urlStr                 paramters:(NSString *)paramters              finshedBlock:(FinishBlock)block;@end

////  HttpRequest.m//  UseBlockCallBack////  Created by Michael on 2/13/14.//  Copyright (c) 2014 EIMS. All rights reserved.//#import "HttpRequest.h"@implementation HttpRequest+ (void)postRequestWithURL:(NSString *)urlStr                 paramters:(NSString *)paramters              finshedBlock:(FinishBlock)block{    HttpRequest *httpRequest = [[HttpRequest alloc]init];    httpRequest.finishBlock = block;        NSURL *url = [NSURL URLWithString:urlStr];    NSMutableURLRequest *requset = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30];    [requset setHTTPBody:[paramters dataUsingEncoding:NSUTF8StringEncoding]];        NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:requset delegate:httpRequest];    NSLog(connection ? @"连接创建成功" : @"连接创建失败");}/** *  接收到服务器回应的时回调 */- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;    if (!self.resultData) {        self.resultData = http://www.mamicode.com/[[NSMutableData alloc]init];"[network]allHeaderFields:%@",[dic description]);    }}/** *  接收到服务器传输数据的时候调用，此方法根据数据大小执行若干次 */- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{    [self.resultData appendData:data];}/** *  数据传完之后调用此方法 */- (void)connectionDidFinishLoading:(NSURLConnection *)connection{    NSString *resultStr = [[NSString alloc]initWithData:self.resultData                                               encoding:NSUTF8StringEncoding];    if (self.finishBlock) {        self.finishBlock(resultStr);    }}/** *  网络请求过程中，出现任何错误（断网，连接超时等）会进入此方法 */- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{    NSLog(@"network error : %@", [error localizedDescription]);        if (self.finishBlock) {        self.finishBlock(nil);    }}@end

[HttpRequest postRequestWithURL:@"http://www.baidu.com"                          paramters:@""                       finshedBlock:^(NSString *dataString) {                           NSLog(@"finish callback block, result: %@", dataString);}];