对iOS网络请求的简单封装，并且使用block回调函数方式

// 废话不多说直接上代码

// RequestHttpClass.h文件

/*封装简单的异步请求*/

#import <Foundation/Foundation.h>

// 相当于定义一个函数指针

typedef void(^FinishLoadBlock)(NSData *);

@interface RequestHttpClass : NSMutableURLRequest <NSURLConnectionDataDele

// 存储异步请求的数据

@property (nonatomic, retain) NSMutableData *data;

@property (nonatomic, retain) NSURLConnection *connection;

@property (nonatomic, copy)FinishLoadBlock block;

- (void)startAsync;

- (void)cancel;

@end

// RequestHttpClass.m 文件

#import "RequestHttpClass.h"

@implementation RequestHttpClass

-(void)startAsync {

self.data = [[NSMutableData alloc] init];

// 发起异步请求

self.connection = [NSURLConnection connectionWithRequest:self delegate:self];

}

- (void)cancel {

[self.connection cancel];

}

// 异步请求每次返回的数据

- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

[self.data appendData:data];

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {

NSLog(@"请求网络出错:%@", error);

}

-(void) dealloc {

[_data release];

[super dealloc];

}

@end

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// RequestData.h 文件

#import <Foundation/Foundation.h>

typedef void(^Completion)(id);

@interface RequestData : NSObject

// 访问天气预报接口

+ (void)getWeatherData:(NSDictionary *)params block: (Completion) block;

@end

// RequestData.m 文件

#import "RequestData.h"

#import "RequestHttpClass.h"

#define BASE_URL @"http://www.weather.com.cn/data/sk/"

@implementation RequestData

+ (void)getWeatherData:(NSDictionary *)params block:(Completion )block {

NSString *cityCode = [params objectForKey:@"code"];

NSString *urlstring = [BASE_URLstringByAppendingFormat:@"%@.html",cityCode];

RequestHttpClass *request = [RequestHttpClass requestWithURL:[NSURL URLWithString:urlstring]];

[request setHTTPMethod:@"GET"];

[request setTimeoutInterval:60];

request.block = ^(NSData *data) {

id ret = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

block(ret);

};

[request startAsync];

}

@end