MyDownloader 实现中 super dealloc 上的 exc_bad_access答案

【问题标题】：exc_bad_access on super dealloc in MyDownloader implementationMyDownloader 实现中 super dealloc 上的 exc_bad_access
【发布时间】：2011-09-13 14:56:33
【问题描述】：

我已经实现了在 Nueburg 的 Programming ios 4 中定义的 MyDownloader 类。当我运行代码时，我在 super dealloc 上获得了一个 exc_bad_access。这本书没有提供关于头文件的描述，所以也许我在那里做错了什么。有人可以帮我看看是什么导致了错误吗？

这是我的头文件：

#import <Foundation/Foundation.h>


@interface MyDownloader : NSURLConnection {
    NSURLConnection *connection;
    NSURLRequest    *request;
    NSMutableData   *receivedData;
}

-(id) initWithRequest: (NSURLRequest*) req;

@property (nonatomic, retain) NSURLConnection   *connection;
@property (nonatomic, retain) NSURLRequest      *request;
@property (nonatomic, retain) NSMutableData     *receivedData;

@end

这是我的实现（减去 didReceiveResponse、didReceiveData、didFailWithError 和 connectionDidFinishLoading 的实现，这些都是直接从书中取出的）：

#import "MyDownloader.h"


@implementation MyDownloader

@synthesize connection;
@synthesize request;
@synthesize receivedData;

-(id) initWithRequest: (NSURLRequest*) req {
    self = [super init];
    if (self) {
        self->request = [req copy];

        // Create a connection, but don't start it yet. The connection will be started with a start message.
        self->connection = [[NSURLConnection alloc] initWithRequest:req delegate:self startImmediately:NO];
        self->receivedData = [[NSMutableData alloc] init];  // initialize where the incoming data will be stored
    }
    return self;
}

- (void)dealloc
{
    [receivedData release];
    [request release];
    [connection release];
    [super dealloc];
}
...
@end

最后，这是我对类的使用：

{
     ...
     if (!self.connections) {
     self.connections = [NSMutableArray array];
     }
     NSString *s = @"https://www.myserver.com/myfile.txt";
     NSURL *url = [NSURL URLWithString:s];
     NSURLRequest *req = [NSURLRequest requestWithURL:url];
     MyDownloader *d = [[MyDownloader alloc] initWithRequest:req];
     [self.connections addObject:d];
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(downloadFinished:) name:@"connectionFinished" object:d];
     [d.connection start];
     [d release];
    ...
}

-(void) downloadFinished: (NSNotification *) n 
{
    MyDownloader *d = [n object];
    NSData *data = nil;
    if ([n userInfo]) {
        NSLog(@"MyDownloader returned an error");
    }
    else {
        data = [d receivedData];
        NSLog(@"MyDownloader returned the requested data");
    }
    [self.connections removeObject:d];
}

【问题讨论】：

您是否需要将MyDownloader 子类化为NSURLConnection？首先尝试使其成为NSObject 的子类
乔，对不起，我没有意识到我应该做些什么来接受答案。我回去接受了所有已回答的答案。向所有之前帮助过我的人道歉，我让你们失望了。
巴迪迪，谢谢。这解决了它。就像我说的，这本书没有给出头文件，我错误地认为它需要是 NSURLConnection 的子类，因为该类需要实现： - (void) connection:(NSURLConnection *)connection didReceiveResponse:, - (void ）连接：（NSURLConnection *）连接didReceiveData：和-（void）connectionDidFinishLoading：。我想我只是不明白这些方法是如何被“连接”知道的，而不是 NSURLConnection 的子类。

标签： objective-c ios memory-management dealloc

【解决方案1】：

Baddidi 给出的解决方案是我应该将我的类子类化为 NSObject，而不是 NSURLConnection。

【讨论】：