Question

作为免责声明，我想说明我对Objective-C和Cocoa相当新。目前我正在尝试编写一个可以将XML数据发送到特定端点的基本应用程序。为此，我创建了一个ServiceRouter类，它使用NSURLConnection将XML数据发布到特定的URL。

ServiceRouter类旨在作为包含特定于Web服务的XML查询的子类的基础。在下面的示例中，我将ServiceRouter子类化为创建ServiceImplementation类。

当生成和发布XML时，我创建了一个ServiceImplementation类的实例，如下所示：

[[ServiceImplementation alloc] createServiceSpecificXML];

这一切似乎都很好。问题是Leaks报告了一些问题。由于缺乏经验，我不确定从哪里开始。在大多数情况下，NSURLConnection代码取自Apple的文档。

遵循基本的内存管理规则，我想我必须在某个时候发布我的ServiceImplementation实例。令我困惑的是，考虑到NSURLConnection的异步特性，应如何处理这个问题。这是自动释放的候选人吗？

我希望有更多Objective-C / Cocoa经验的人可以看一看并告诉我，我是否朝着正确的方向前进。

这是ServiceRouter类：

@interface ServiceRouter : NSObject {
    NSMutableData *receivedData;
}

-(void)postXMLToURL:(NSString *)url xml:(NSString *)xmlData;
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data;
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error;
-(void)connectionDidFinishingLoading:(NSURLConnection *)connection;
@end

@implementation ServiceRouter

- (void)postXMLToURL:(NSString *)url xml:(NSString *)xmlData
{
    NSLog(@"Posting XML to URL: %@", url);

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
    [request setHTTPMethod:@"POST"];
    [request setValue:@"application/xml" forHTTPHeaderField:@"Content-type"];
    [request setValue:@"application/xml" forHTTPHeaderField:@"Accept"]; 

    [request setValue:[NSString stringWithFormat:@"%d", [xmlData length]] forHTTPHeaderField:@"Content-length"];
    [request setHTTPBody:[xmlData dataUsingEncoding: NSUTF8StringEncoding]];

    NSURLConnection *connection = [[[NSURLConnection alloc] initWithRequest:request delegate:self] autorelease];
    if(connection) {
        NSLog(@"Connection created");
        receivedData = [[NSMutableData data] retain];
    } else {
        NSLog(@"Issue with connection!");
    }
}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    if([response respondsToSelector:@selector(statusCode)])
    {
        int statusCode = [((NSHTTPURLResponse *)response) statusCode];
        NSLog(@"HTTP Response code: %i", statusCode);
    }
    NSLog(@"Received response");
    [receivedData setLength:0];
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"Received data: %@", data);
    [receivedData appendData:data];
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    [connection release];
    [receivedData release];

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

-(void)connectionDidFinishingLoading:(NSURLConnection *)connection
{
    NSLog(@"Succeeded! Received %d bytes of data", [receivedData length]);

    [connection release];
    [receivedData release];
}
@end

这是我的ServiceImplementation类：

@interface ServiceImplementation : ServiceRouter {
}
-(void) createServiceSpecificXML;
@end

@implementation ServiceImplementation

-(void) createServiceSpecificXML
{
    NSString *xmlData = @"<example><ignore/></example>";
    [super postXMLToURL:@"http://site.com/endpoint.xml" xml:xmlData];
}

@end

Answer 1

您永远不会初始化实例。仅仅分配是不够的。您必须致电init或其他初始值设定项 - 最好与alloc在同一行。

从[[NSMutableData data] retain]的（工作但奇怪的）构造中，我猜你还没有读过很多Apple的基本引物。我建议至少The Objective-C Programming Language和memory management guide。两者都不长，在这两者之间，我认为你会清除很多不确定因素。

NSURLConnection泄漏问题

1 个答案: