iOS: a promising http connection framework - MKNetworkKit

ref links:

http://blog.mugunthkumar.com/products/ios-framework-introducing-mknetworkkit/

http://www.cocoachina.com/bbs/simple/?t93181.html

它包含了检测网络的代码 "Reachability" (http://developer.apple.com/library/ios/#samplecode/Reachability/Introduction/Intro.html)，用来检测网络是否reachable，以及网络是3g还是wifi。

它支持ARC feature

它是ASIHTTPRequest and AFNetworking的混合体，另外还提供一些其他features。

With MKNetworkKit, it’s hard to write ugly networking code. 即使用MKNetworkKit写出的代码会很优雅

Download

http://github.com/mugunthkumar/mknetworkkit

Installation

1. 把MKNetworkKit lib添加到你的project。解压之后，把整个"MKNetworkKit“目录拖到Xcode里你的project的root node上，在弹出的窗口里tick "copy items into destination group's folder" option, select "create groups for any added folders" option, tick your project in "Add to targets" option, click "Finish".
2. 添加4个framework: CFNetwork.Framework, SystemConfiguration.framework, Security.framework and ImageIO.framework: select project root node, 在旁边的panel选择"Targets"的node，select "Build Phases" tab, expand "Link binary with Libraries", click "+" button to add these 4 frameworks。添加之后，这3个frameworks会添加在project root node下，建议把它们move to "Frameworks" folder
3. 在"Supporting Files"目录下的xxx-Prefix.pch file里添加下列代码   

   #import"MKNetworkKit.h"

   
   
4. Delete MKNetworkKit/Categories/NSAlert+MKNetworkKitAdditions.h and .m fileif you are building for iOS.
5. Delete MKNetworkKit/Categories/UIAlertView+MKNetworkKitAdditions.h and .m fileif you are building for Mac.

6. build your project

* MKNetworkKit好像使用Reachability不当，apple建议是在第一次连接失败后才check reachability，而MkNetworkKit是在初始化MKNetworkEngine时，初次连接之前就check reachability。(ref link: https://github.com/MugunthKumar/MKNetworkKit/issues/19)

最简单的使用MKNetworkKit的代码 （把下面代码复制到ViewController的viewDidLoad method里）

    MKNetworkEngine *engine=[[MKNetworkEngine alloc] initWithHostName:@"download.finance.yahoo.com" customHeaderFields:nil];

    MKNetworkOperation *op = [engine operationWithPath:@"d/quotes.csv?e=.csv&f=sl1d1t1&s=SGDUSD=X" 
                                              params:nil 
                                          httpMethod:@"GET"];
    
    [op onCompletion:^(MKNetworkOperation *completedOperation)
     {
         DLog(@"Data from server %@", [completedOperation responseString]);
     }onError:^(NSError* error) {
         DLog("error: %@",error.description);
     }];
    
    [engine enqueueOperation:op];

注意：其实MKNetworkKit不建议直接在viewcontroller里直接使用MKNetworkEngine and MKNetworkOperation这2个classes，而应该创建一个MKNetworkEngine的子类，并把http operation都写在该子类里，viewcontroler则通过调用该子类来进行http操作（viewcontroller传递给子类的是一个回调block，这样当http operation complete时就通过这个block来通知view controller。相见MKNetworkKit examples里的viewcontroller.m and YahooEngine.m files)

下面是一个比较完整的例子。它是通过2个open source lib: MKNetworkKit and MBProgressHud来获取web page content。它包括以下几个features:

1. 异步

2. check internet connection reachability

3. show loading progress

如果要查看MKNetworkKit如何处理response format为json的例子，参看http://blog.csdn.net/totogogo/article/details/7402870

前提：add MKNetworkKit and MBProgressHud to your project

1. 在view controller .h file里实现<MBProgressHUDDelegate>

#import"MBProgressHUD.h"

@interface ViewController :UIViewController <MBProgressHUDDelegate>

2. 在view controller .m file里添加下列代码

- (IBAction)getCapHomePageContent:(id)sender {
	MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
	[self.view addSubview:hud];	
	// Regiser for HUD callbacks so we can remove it from the window at the right time
	hud.delegate = self;
    
    //show pregress hud
	[hud show:YES];
    
    [[CAPHttpService alloc] getCapHomePageContent:^(NSMutableArray *newsTitleList) {
        //hide pregress hud
        [hud hide:YES];
        
        //todo: handle var newsTitleList
        
    } onError:^(NSError* error) {
        //hide pregress hud
        [hud hide:YES];

        //show alert window for error
        if(error.code==-1009) //means no internet connection
        {
            [[[UIAlertView alloc] initWithTitle:@"Cannot Get Data"                              
                                        message:@"Cannot get data because it could not connect to the server"  
                                       delegate:nil
                              cancelButtonTitle:@"OK"
                              otherButtonTitles:nil] show];
            
        } else {
            [[[UIAlertView alloc] initWithTitle:@"Error"                              
                                        message:[NSString stringWithFormat:@"Error code: %@", error.code]  
                                       delegate:nil
                              cancelButtonTitle:@"OK"
                              otherButtonTitles:nil] show];
        }
    }];

}

既然实现"<MBProgressHUDDelegate>" 接口，就要添加"hudWasHidden" method，该方法是一个回调方法，当你执行"[hud hide:YES];"时，就会回调它

- (void)hudWasHidden:(MBProgressHUD *)hud {
	// Remove HUD from screen when the HUD was hidded
	[hud removeFromSuperview];
	hud = nil;
}

3. 创建一个objective c class (假设为CAPHttpService)，用于处理http request and response

CAPHttpService.h

#import <Foundation/Foundation.h>

@interface CAPHttpService : NSObject
typedef void (^NewsTitleListResponseBlock)(NSMutableArray *newsTitleList);

-(void) getCapHomePageContent:(NewsTitleListResponseBlock) completion
                      onError:(MKNKErrorBlock) error;

@end

CAPHttpService.m

#import "CAPHttpService.h"

@implementation CAPHttpService

-(void) getCapHomePageContent:(NewsTitleListResponseBlock) completion
                      onError:(MKNKErrorBlock) handleError{
    MKNetworkEngine *engine=[[MKNetworkEngine alloc] initWithHostName:@"cap.cityu.edu.hk" customHeaderFields:nil];

    MKNetworkOperation *op=[engine operationWithPath:@"studentlan/"
                                            params:nil
                                        httpMethod:@"GET"
                                               ssl:1];
    
    [op onCompletion:^(MKNetworkOperation *operation) { 
        
        DLog(@"%@", [operation responseStringWithEncoding:NSUTF8StringEncoding]);
        //todo: parse var "operation" to news title list
        NSMutableArray *newsTitleList=nil;
        completion(newsTitleList);
        } 
        onError:handleError
     ];
    
    [engine enqueueOperation:op];
    
}

@end

注意认真理解CAPHttpService.m里getCapHomePageContent的定义和在viewcontroller里对其的调用，可以看到使用block，使得代码变得优雅!