iOS httprequest数据恢复

Question

我在从iOS上的http客户端获取数据时遇到了问题。这是我的client类的代码

@synthesize receivedData;

- (void) HTTPRequest1 :(NSURL *) url {
        NSURLRequest *req = [NSURLRequest requestWithURL: url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];

    NSURLConnection *connect = [[NSURLConnection alloc] initWithRequest:req delegate:self];


    if (connect) {
        receivedData =[NSMutableData data];

    }
    else {

    }


}

-(void) connection:(NSURLConnection*) connection didReceiveResponse:(NSURLResponse *)response{
    [self.receivedData setLength:0];


}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{

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

}

- (void)connection:(NSURLConnection *)connection
  didFailWithError:(NSError *)error
{

    NSLog(@"Connection failed! Error - %@ %@",
          [error localizedDescription],
          [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{

    NSLog(@"Succeeded! Received %d bytes of data",[receivedData length]);



}

但是当我试图从这个客户端获取数据时：

NSURL *url = [NSURL URLWithString:@"http://ya.ru"];
MAHTTPClient *client = [MAHTTPClient alloc];
[client HTTPRequest1:url];
 NSMutableData *data = client.receivedData;

数据变量为空，但收到了数据(NSLog显示下载了一些字节的数据)。问题是，我的应用程序在还没有从服务器上下载数据的时候就试图检索数据(有200ms的差异)，有没有办法让主线程一直等到connectionDidFinishLoading被调用？

Answer 1

您在此处分配的NSMutableData：

if (connect) {
    receivedData =[NSMutableData data];

}
else {

}

可能是自动释放的，因为您正在使用一个返回自动释放对象的方法。

你可以这样做：

self.receivedData = [NSMutableData data]; 

如果receivedData是strong/retain属性或

receivedData = [[NSMutableData alloc] init]; 

//但是您需要了解内存管理规则，以确保您不会在这里泄漏内存。