NSURLRequest 簡單的網絡請求

NSURLRequest 簡單的網絡請求

- (void)viewDidLoad
{
    [super viewDidLoad];


NSURL* url = [NSURL URLWithString:@"http://img21.mtime.cn/mg/2012/03/25/112544.76654880.jpg"];
_imageData = [[NSMutableData alloc] init];

//進度條
_pv = [[UIProgressView alloc] initWithFrame:CGRectMake(50, 50, 220, 20)];
[self.view addSubview:_pv];
[_pv release];


//創建一個請求

//NSURLRequest request = [NSURLRequest requestWithURL:url];
    NSURLRequest request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:30];
    //發送請求
    [NSURLConnection connectionWithRequest:request delegate:self];
}
//接收響應頭

(void)connection:(NSURLConnection )connection didReceiveResponse:(NSURLResponse )response{
  NSLog(@"接收到響應頭");
  [_imageData setLength:0];
  //拿到響應體長度
  NSHTTPURLResponse res = (NSHTTPURLResponse)response;
  _length = [[res.allHeaderFields objectForKey:@"Content-Length"] floatValue];
  NSLog(@"length:%f",_length);
  //是否 開啟 網絡開關 狀態欄的
  [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
}

//接收響應體,下載數據
/
 0 1 2 3 4 5 6 7 8 9
 0 1
     2 3 4 
           5 6 7
                 8 9
 0 1 2 3 4 5 6 7 8 9
 /

(void)connection:(NSURLConnection )connection didReceiveData:(NSData )data{
  NSLog(@"接收響應體");
  //把每次下載的數據添加到一起
  [_imageData appendData:data];
//刷新進度條
  [_pv setProgress:_imageData.length / _length animated:YES];
}


//成功

(void)connectionDidFinishLoading:(NSURLConnection )connection{
  NSLog(@"成功");
  UIImage image = [UIImage imageWithData:_imageData];
  self.view.backgroundColor = [UIColor colorWithPatternImage:image];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}


//失敗

(void)connection:(NSURLConnection )connection didFailWithError:(NSError )error{
  NSLog(@"失敗");
  [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}</pre>