iOS开发之网络连接方式

连接方式有两种：同步和异步。

同步连接：1. 使用sendSynchronousRequest:requestreturningResponse:&response error:&error方法。2.同步连接会出现出现卡死的现象，用户交互不好，影响用户体验。

宏定义一个网址#define kURL@"http://ipad-bjwb.bjd.com.cn/DigitalPublication/publish/Handler/APINewsList.ashx？date=20131129&startRecord=1&len=5&udid=1234567890&terminalType=Iphone&cid=213"

下面的是一个同步的GET请求

NSURL * url= [NSURL URLWithString:kURL];

NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:(NSURLRequestUseProtocolCachePolicy) timeoutInterval:100
];

NSURLResponse* response = nil;

NSError* error = nil;

NSData* data = [NSURLConnection sendSynchronousRequest:requestreturningResponse:&response error:&error
];

NSDictionary* dic = [NSJSONSerialization JSONObjectWithData:dataoptions:(NSJSONReadingMutableContainers)error:nil];

NSLog(@"%@",dic);

异步连接：1.异步连接可以分为两种。

Block 和delegate。

带Block的方法是 [ NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueuecurrentQueue] completionHandler:^(NSURLResponse *response, NSData*data, NSError *connectionError) {}];

该方法需要三个参数，分别表示如下含义：

request：请求；

queue：队列。一般情况下是CurrentQueue。

该方法将响应、数据、错误封装到了Blcok.

注意：Block中华的代码不会立即执行，只有当服务器请求完数据之后才会执行Block里面的代码。

面临问题：由于Block里面的代码不会立即执行，界面展示要比数据获取早，那当获取完数据之后如何通知界面呢。

NSURL * url= [NSURL URLWithString:kURL];

NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:(NSURLRequestUseProtocolCachePolicy) timeoutInterval:10];

[ NSURLConnection sendAsynchronousRequest:requestqueue:[NSOperationQueuecurrentQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError*connectionError)
{

NSDictionary * dic =[NSJSONSerialization JSONObjectWithData:dataoptions:(NSJSONReadingMutableContainers)error:&connectionError];

NSLog(@"%@",dic);

//当数据使用完成之后，在Block里面重新导入数据

[self.tableView reloadData];

}];

带Delegate的异步连接

1.将数据下载进度封装到了协议中，所以一般情况下如果要显示下载进度会使用带Delegate的连接。

2.带Delegate的连接也是异步连接。界面要先显示出来之后才能获取到数据，所以面临的问题和Block面临的问题一致；

注意事项：代理中有一个方法名为

didReceiveData:该方法参数Data，不是已经下载的总Data，需要自己拼接Data数据

宏定义一个网址

#define mURL @"http://fdfs.xmcdn.com/group6/M03/3B/73/wKgDg1UxBYyCWoFZAHYGKdSPN90325.mp3"

网址内容是一段音频内容

#import "RootViewController.h"

#import

#define kURL @"http://ipad-bjwb.bjd.com.cn/DigitalPublication/publish/Handler/APINewsList.ashx?date=20131129&startRecord=1&len=5&udid=1234567890&terminalType=Iphone&cid=213"

#define mURL @"http://fdfs.xmcdn.com/group6/M03/3B/73/wKgDg1UxBYyCWoFZAHYGKdSPN90325.mp3"

@interface RootViewController ()<</span>NSURLConnectionDataDelegate>

{

long long _totalLength;//总长度}

}

@property(nonatomic,retain)NSMutableData *
receivedData;//已经接收到的数据

@property(nonatomic,retain)UIProgressView *
progressView;//进度条

@end

@implementation RootViewController

-(void)dealloc

{

[_receivedDatarelease];

[_progressViewrelease];

[superdealloc];

}

-(NSMutableData *)receivedData

{

if (_receivedData == nil ){

self.receivedData =
[NSMutableData dataWithCapacity:0];

}

return_receivedData;

}

-(UIProgressView *)progressView

{

if (_progressView == nil ){

self.progressView =
[[[UIProgressView alloc]initWithProgressViewStyle:(UIProgressViewStyleDefault)]autorelease];

_progressView.frame = CGRectMake(30,300, 300, 30);

[self.view addSubview:_progressView];

}

return_progressView;

}

NSURL * url= [NSURL URLWithString:mURL];

NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:(NSURLRequestUseProtocolCachePolicy) timeoutInterval:15];

[[[NSURLConnection alloc]initWithRequest:requestdelegate:self]autorelease];//自带一个初始化方法，接收协议接收的是<</span>NSURLConnectionDataDelegate>这个协议

实现协议中的方法

//接收到服务器 响应

-(void)connection:(NSURLConnection *)connectiondidReceiveResponse:(NSURLResponse*)response

{

_totalLength= response.expectedContentLength;//总长度

NSLog(@"%lld",_totalLength);

}

//从服务器接收到数据

-(void)connection:(NSURLConnection *)connectiondidReceiveData:(NSData *)data

{

[self.receivedData appendData:data];//拼接Data

self.progressView.progress = 1.0 * self.receivedData.length / _totalLength;//读取进度

}

//数据获取完毕

-(void)connectionDidFinishLoading:(NSURLConnection *)connection

{

NSError* error = nil;

AVAudioPlayer* player = [[AVAudioPlayer alloc]initWithData:self.receivedDataerror:&error];

if (error == nil )
{

[player prepareToPlay];

[player play];

}

else{

NSLog(@"%@",error);

}

}

//出现错误

-(void)connection:(NSURLConnection *)connectiondidFailWithError:(NSError*)error

{

NSLog(@"%@",[error localizedDescription]);

}