第二個異步NSURLConnection不調用委託方法

Question

從我的ApplicationDelegate中，我通過網絡進行NSURLConnection獲取（它被包裝在一個類中，如下所示）。這一個似乎正常工作：我得到了didReceiveData中的所有數據，並得到了完成調用connectionDidFinishLoading。在connectionDidFinishLoading的結尾處，我實例化了一個或多個稍微不同類型的包裝類，但它們本質上是相同的。問題是第二個NSURLConnection的委託永遠不會調用它的方法。

我看了看manydifferentanswers，但都無濟於事。我沒有產生任何新線程，並且所有[NSThread isMainThread]檢查我在整個代碼中散佈的信息都返回true。

我很難過。誰能幫我嗎？下面是相關的代碼：

應用代表：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { 

    ConnectionWrapper* w = [[ConnectionWrapper alloc] initWithParams:self 
    url:[NSURL URLWithString:<url>]]; 
[w beginFetch]; 

    return YES; 
} 

... 

-(void)fetchCompleted:(NSURL*)url directory:(NSString*)directory 
{ 
NSLog(@"fetch completed"); 
} 

-(void)fetchFailed:(NSURL*)url 
{ 
NSLog(@"fetch failed"); 
} 

... 

ConnectionWrapper：

-(id)initWithParams:(id<ConnectionWrapperDelegate>)d url:(NSURL*)url 
{ 
    delegate = d; 

    connURL = url; 

    return [self init]; 
} 

-(void)beginFetch 
{ 
    NSURLRequest* request = [[NSURLRequest alloc] initWithURL:connURL]; 
    NSURLConnection* conn = [[NSURLConnection alloc] initWithRequest:request delegate:self]; 

    [conn release]; 
    [request release]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{ 
    NSLog(@"append"); 
    [responseData appendData:data]; 
} 

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

    DifferentConnectionWrapper* w = [[DifferentConnectionWrapper alloc] initWithParams:self 
     url:[NSURL URLWithString:<different url>]]; 
    [w beginFetch]; 
} 

-(void)fetchCompleted:(NSURL*)URL 
{ 
    NSLog(@"completed: %@", URL); 
} 

-(void)fetchFailed:(NSURL*)URL 
{ 
    NSLog(@"failed"); 
} 

DifferentConnectionWrapper：

- （ID）initWithParams：（ID）d網址：（NSURL *） url { delegate = d;

connURL = url; 

    return [self init]; 
} 

-(void)beginFetch 
{ 
    NSURLRequest* request = [[NSURLRequest alloc] initWithURL:connURL]; 
    NSURLConnection* conn = [[NSURLConnection alloc] initWithRequest:request delegate:self]; 

    [conn release]; 
    [request release]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{ 
    NSLog(@"append"); 
    [responseData appendData:data]; 
} 

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

    DifferentConnectionWrapper* w = [[DifferentConnectionWrapper alloc] initWithParams:self 
     url:[NSURL URLWithString:<different url>]]; 
    [w beginFetch]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{ 
    NSLog(@"got response"); 
    [responseData setLength:0]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{ 
    NSLog(@"got data"); 
    [responseData appendData:data]; 
} 

- (void) connectionDidFinishLoading: (NSURLConnection*) connection 
{ 
    NSLog(@"image saver completed: %@", connURL); 
} 

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{ 
    NSLog(@"error"); 
} 

ConnectionWrapper和DifferentConnectionWrapper具有類似的功能，但爲簡潔起見，我省略了其他邏輯。

感謝您的幫助。我很感激。

Answer 1

確定。事實證明，這個錯誤是由我錯過的東西造成的。在第二次請求之後，我正在進入一個艱難的環境，這可能會造成任何事情。一旦我解決了這個問題，一切都很順利。

感謝您的幫助。

Answer 2

我相信問題是，你在釋放的-beginFetch URL連接：

-(void)beginFetch 
{ 
    NSURLRequest* request = [[NSURLRequest alloc] initWithURL:connURL]; 
    NSURLConnection* conn = [[NSURLConnection alloc] initWithRequest:request delegate:self]; 

    [conn release]; 
    [request release]; 
} 

的URL連接對象應保持活力和釋放時的連接完成加載：

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

    // *** Release the connection and whatever data you’ve kept related to 
    // this particular connection 
    [connection release]; 
    [responseData release]; 
    // *** or [responseData setLenght:0]; depending on how you’re 
    // managing responseData 

    DifferentConnectionWrapper* w = [[DifferentConnectionWrapper alloc] initWithParams:self 
     url:[NSURL URLWithString:<different url>]]; 
    [w beginFetch]; 
} 

或出現錯誤時：

- (void)connection:(NSURLConnection *)connection 
    didFailWithError:(NSError *)error 
{ 
    // *** Release the connection and whatever data you’ve kept related to 
    // this particular connection 
    [connection release]; 
    [responseData release]; 
    // *** or [responseData setLenght:0]; depending on how you’re 
    // managing responseData 

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

---

編輯：你的初始化器是怪異一點點：

-(id)initWithParams:(id<ConnectionWrapperDelegate>)d url:(NSURL*)url 
{ 
    delegate = d;  
    connURL = url; 
    return [self init]; 
} 

有沒有辦法知道會發生什麼，除非我們看到代碼爲-init和，無論如何，這應該是指定的初始化器，所以它無論如何不應該發送-init到self。此外，您應該保留傳遞給初始程序的url對象。

下更有意義：

-(id)initWithParams:(id<ConnectionWrapperDelegate>)d url:(NSURL*)url 
{ 
    self = [super init]; 
    if (self) { 
     delegate = d;  
     connURL = [url retain]; 
    } 
    return self; 
} 

不要忘了釋放-dealloc的url對象或當你指定其它值connURL。

Answer 3

一些事情：我沒有看到didFailWithError：在你的第一個包裝類中，並且（有點偏離主題）是你用你的DifferentConnectionWrapper * w泄漏了內存嗎？

無論如何，我會嘗試的是：看看你是否可以直接從appDelegate而不是ConnectionWrapper調用DifferentConnectionWrapper。 而且我會嘗試在任何情況下解耦這兩個呼叫。當第一個完成並調用appDelegate時，你不能從那裏啓動你的DifferentConnectionWrapper嗎？

我知道這並不能說明你的問題，但你可能會得到它的工作（以及其中這兩件事情是更重要的，是一個完全不同的討論。）