IOS开发之在服务器端获取数据，保存网页的Demo学习

新建一个SingleViewApplication应用, 在storyboard中拖2个label，然后创建他们的弱链接，得到如下的代码：

@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UILabel *labelResult;

.m文件的整体变量申明代码如下：

#import "ViewController.h"

@interface ViewController ()

@property (retain, nonatomic) NSURLConnection * connection;
@property (retain, nonatomic) NSMutableData * data;
@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UILabel *labelResult;

@end

在viewDidLoad中添加以下代码：

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

self.label.text = @"正在请求数据";

//访问服务器获取json数据
NSString *urlSring = @"http://www.weather.com.cn/data/cityinfo/101020100.html";
NSURL *url = [NSURL URLWithString:urlSring];

//step2:实例化一个request
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0];

//创建链接
self.connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (self.connection) {
NSLog(@"创建成功");

}else{
NSLog(@"创建失败");//(@"创建失败“);
}

}

添加如下函数：

-(void) connection:(NSURLConnection *) connection didReceiveResponse:(NSURLResponse *)response{
//接受一个服务端回话，再次一般初始化接受数据的对象
NSMutableData *data = [NSMutableData alloc];
self.data = data;
NSLog(@"接受服务端回话");
}

-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
//接受返回数据，这个方法可能会被调用多次，因此将多次返回数据加起来
NSInteger datalength = [data length];
NSLog(@"返回数据量: %ld", (long)datalength);
[self.data appendData:data];
}

-(NSString *)dataFilePath:(NSString *)fileName{
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
NSString *document = [path objectAtIndex:0];
NSLog(@"path:   %@",path);
return [document stringByAppendingPathComponent:fileName];
}

-(void) connectionDidFinishLoading:(NSURLConnection *)connection{
//NSLog(@"%d", [self.datalength]);
self.label.text = @"请求结束";

NSString *mystr = [[NSString alloc]initWithData:self.data encoding:NSUTF8StringEncoding];
[mystr writeToFile:[self dataFilePath:@"百度图片－全球最大中文图片库.html"] atomically:YES encoding:NSUTF8StringEncoding error:nil];
NSLog(@"最后的结果%@", mystr);
self.label.text = @"最后的结果";
self.labelResult.text = mystr;

//    NSDictionary *weather = [NSJSONSerialization JSONObjectWithData:self.data options:NSJSONReadingMutableContainers  error:nil];
//    NSLog(@"%@",weather);
//    [weather writeToFile:[self dataFilePath:@"weather.plist"] atomically:YES];
//    NSLog(@"%@",weather);

}

-(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
self.label.text = @"链接失败";
}

注意：在第二个label显示获取信息的时候，将显示行数修改，并将label拉高拉宽，否则显示不全，如图：右边属性中的Line改为5；
v

好了，现在运行即可。结果：