代码语言：javascript复制
//网络访问获取数据
//定义一个UIWebView属性，用来展示数据
@property (strong, nonatomic) IBOutlet UIWebView *myWebView;
//.......
//使用NSURLConnection发送异步请求获取数据
- (void)getData:(id)sender{
//访问的网站地址
NSString *str = @"http://www.apple.com/";
//实例化NSURL对象
NSURL *url = [NSURL URLWithString:str];
//实例化NSURLRequest对象
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//实例化操作队列
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
//发送异步请求
[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:
^(NSURLResponse *response, NSData *data, NSError *error) {
//获得网络抓取的数据
if ([data length] > 0 && error == nil){
//将NSData转换为NSString
NSString *html = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
//使用UIWebView显示网页
[self.myWebView loadHTMLString:html baseURL:nil];
NSLog(@"html = %@", html);
}
}];
}
/*使用NSUrlConnection发送同步请求获得数据
使用同步请求的时候，最好在单独的一个线程中进行，
这样可以避免程序阻塞
*/
- (void)getDataTwo:(id)sender{
//全局队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//异步并行队列，开辟一个新线程
dispatch_async(queue, ^{
NSURL *url = [NSURL URLWithString:@"http://www.apple.com"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSURLResponse *response;
NSError *error;
//NSURLConnection发送同步请求，获得数据
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
//判断结果
if ([data length] > 0 && error == nil){
NSString *html = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"html = %@", html);
}
});
}/**
* 使用NSMutableURLRequest向服务器发送POST请求获取数据
*/
- (void)getDataThree:(id)sender{
//创建一个线程
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//执行异步任务
dispatch_async(queue, ^{
//获取新浪的天气预报信息网址
//http://php.weather.sina.com.cn/xml.php?city=����&password=DJOYnieT8234jlsK&day=0
//在block中从网络获取数据
NSString *str = @"http://php.weather.sina.com.cn/xml.php";
//创建NSURL对象
NSURL *url = [NSURL URLWithString:str];
//可变URL请求
NSMutableURLRequest *mRequest = [[NSMutableURLRequest alloc] init];
//为请求设置URL
[mRequest setURL:url];
//设置请求超时时间
[mRequest setTimeoutInterval:10];
//设置请求方法为post
[mRequest setHTTPMethod:@"POST"];
//body内容
NSString *body = @"city=����&password=DJOYnieT8234jlsK&day=0";
//设置body
[mRequest setHTTPBody:[body dataUsingEncoding:NSUTF8StringEncoding]];
//获得响应
NSURLResponse *response;
NSError *error;
//获得返回数据
NSData *data = [NSURLConnection sendSynchronousRequest:mRequest returningResponse:&response error:&error];
//将NSData转换成字符串
NSString *content = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
//使用UIWebView加载数据
[self.myWebView loadHTMLString:content baseURL:nil];
//输出结果
NSLog(@"content = %@", content);
});
}数据解析
在网络编程中，从服务器获取的数据格式大致分为两种：JSON和XML。其中JSON作为一种轻量级的数据交换格式，正在逐步取代XML, 成为网络数据的通用格式。
测试列子：调用一个天气预报的API, 地址是：http://m.weather.com.cn/data/101010100.html
代码语言：javascript复制/**
* 使用系统自带库NSJSONSerialization解析json数据
访问http://m.weather.com.cn/data/101010100.html ，返回结果为：
{"weatherinfo":{"city":"北京","city_en":"beijing","date_y":"2014年3月4日","date":"","week":"星期二","fchh":"11","cityid":"101010100","temp1":"8℃~-3℃","temp2":"8℃~-3℃","temp3":"7℃~-3℃","temp4":"8℃~-1℃","temp5":"10℃~1℃","temp6":"10℃~2℃","tempF1":"46.4℉~26.6℉","tempF2":"46.4℉~26.6℉","tempF3":"44.6℉~26.6℉","tempF4":"46.4℉~30.2℉","tempF5":"50℉~33.8℉","tempF6":"50℉~35.6℉","weather1":"晴","weather2":"晴","weather3":"晴","weather4":"晴转多云","weather5":"多云","weather6":"多云","img1":"0","img2":"99","img3":"0","img4":"99","img5":"0","img6":"99","img7":"0","img8":"1","img9":"1","img10":"99","img11":"1","img12":"99","img_single":"0","img_title1":"晴","img_title2":"晴","img_title3":"晴","img_title4":"晴","img_title5":"晴","img_title6":"晴","img_title7":"晴","img_title8":"多云","img_title9":"多云","img_title10":"多云","img_title11":"多云","img_title12":"多云","img_title_single":"晴","wind1":"北风4-5级转微风","wind2":"微风","wind3":"微风","wind4":"微风","wind5":"微风","wind6":"微风","fx1":"北风","fx2":"微风","fl1":"4-5级转小于3级","fl2":"小于3级","fl3":"小于3级","fl4":"小于3级","fl5":"小于3级","fl6":"小于3级","index":"寒冷","index_d":"天气寒冷，建议着厚羽绒服、毛皮大衣加厚毛衣等隆冬服装。年老体弱者尤其要注意保暖防冻。","index48":"冷","index48_d":"天气冷，建议着棉服、羽绒服、皮夹克加羊毛衫等冬季服装。年老体弱者宜着厚棉衣、冬大衣或厚羽绒服。","index_uv":"中等","index48_uv":"中等","index_xc":"较适宜","index_tr":"一般","index_co":"较舒适","st1":"7","st2":"-3","st3":"8","st4":"0","st5":"7","st6":"-1","index_cl":"较不宜","index_ls":"基本适宜","index_ag":"易发"}}
*/
- (void)getWeatherData:(id)sender{
NSURL *url = [NSURL URLWithString:@"http://m.weather.com.cn/data/101010100.html"];
NSURLRequest *requst = [NSURLRequest requestWithURL:url];
//发送异步请求
[NSURLConnection sendAsynchronousRequest:requst queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if ([data length] > 0 && error == nil){
//将NSData转换成NSDictionary
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil];
//结果为字典中有字典，获得key为weatherinfo的字典
NSDictionary *dic2 = [dic objectForKey:@"weatherinfo"];
//遍历字典
for (NSString *key in dic2) {
NSLog(@"%@:%@", key, [dic2 objectForKey:key]);
}
}
}];
}XML解析可以通过苹果自带的API -> NSXMLParser和其代理类NSXMLParserDelegate。
NSXMLParseDelegate代理类中有一组方法用来检测文档的读取状态，例如，文档开始、文档结束、元素开始、元素结束、内容开始等；
解析XML数据的基本思路是，在元素开始时创建一个空对象，找到内容时，读取内容并为对象的属性赋值，元素结束时将对象添加到集合中。
示例代码：
代码语言：javascript复制//创建一个Customer类
@interface Customer : NSObject
@property (nonatomic, assign) int cid; //客户id
@property (nonatomic, retain) NSString *name;//客户姓名
@property (nonatomic, assign) int age; //客户年龄
@end//先定义4个属性
@property (nonatomic, retain) Customer *customer; //客户实例
@property (nonatomic, retain) NSXMLParser *parser; //xml解析器
@property (nonatomic, retain) NSMutableArray *array; //可变数组
@property (nonatomic, strong) NSString *currrentElement; //当前元素
//初始化方法
- (void)initParser{
//初始化数组，用来容纳客户对象
self.array = [NSMutableArray arrayWithCapacity:10];
//获得客户XML文件的URL路径
NSString *str = [[NSBundle mainBundle] pathForResource:@"customers" ofType:@"xml"];
//将客户XML转换成NSData
NSData *data = [[NSData alloc] initWithContentsOfFile:str];
//实例化XML解析器
self.parser = [[NSXMLParser alloc] initWithData:data];
//设置代理
self.parser.delegate = self;
}
/**
* 实现协议代理方法
*/
//读文档开始
- (void)parserDidStartDocument:(NSXMLParser *)parser{
NSLog(@"parserDidStartDocument...");
}
//读文档结束
- (void)parserDidEndDocument:(NSXMLParser *)parser{
NSLog(@"parserDidEndDocument....");
}
//读元素开始
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
NSLog(@"didStartElement...");
self.currrentElement = elementName;
if ([self.currrentElement isEqualToString:@"customer"]){
self.customer = [[Customer alloc] init];
}
}
//找到内容
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
NSLog(@"foundCharacters....");
if ([self.currrentElement isEqualToString:@"id"]){
int cid = [string integerValue];
[self.customer setCid:cid];
}
else if ([self.currrentElement isEqualToString:@"name"]){
[self.customer setName:string];
}
else if ([self.currrentElement isEqualToString:@"age"]){
[self.customer setAge:[string integerValue]];
}
}
//读元素结束
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
NSLog(@"didEndElement...");
if ([elementName isEqualToString:@"customer"]){
[self.array addObject:self.customer];
}
self.currrentElement = nil;
}
//开始解析方法
- (void)parse:(id)sender{
//删除数组中的所有数据
[self.array removeAllObjects];
//开始解析
[self.parser parse];
//获得数组大小
NSInteger count = [self.array count];
}
