奇怪的錯誤 - 可以訪問NSURLConnection的＆NSMutableData的描述方法，但不是他們的ivars

Question

所以我得到了類：
DataFetcher.h

#import <Foundation/Foundation.h> 

@interface DataFetcher : NSObject 
{ 
    NSURLConnection *networkConnection; 
    NSMutableData *recievedData; 
    BOOL isFetchingFinished; 
} 

@property (nonatomic, retain) NSMutableData *recievedData; 
@property (nonatomic, retain) NSURLConnection *networkConnection; 

- (void)fetchDataWithRequest:(NSMutableURLRequest *)request; 

DataFetcher.m：

#import "DataFetcher.h" 

@implementation DataFetcher 

@synthesize recievedData; 
@synthesize networkConnection; 

- (id)init 
{ 
    self = [super init]; 
    if (self) { 
     NSMutableData *data = [[NSMutableData alloc] initWithLength:0]; 
     self.recievedData = data; 
     [data release]; 
    } 

    return self; 
} 

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{ 
    NSLog(@"Connection Error:%@\n Failure Reason:%@", [error localizedDescription], [error localizedFailureReason]); 
    [networkConnection release]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{ 
} 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{ 
    [self.recievedData appendData:data]; 
} 

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{ 
    [networkConnection release]; 
    NSLog(@"%@", self.recievedData.length); 
    [self processData]; 
} 

- (void)fetchDataWithRequest:(NSMutableURLRequest *)request 
{ 
    NSURLConnection *aConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO]; 
    self.networkConnection = aConnection; 
    [aConnection release]; 
    [self.networkConnection start]; 
    if(!self.networkConnection) 
    { 
     NSLog(@"Connection failed! recieved nil at alloc point"); 
    } 
} 

- (void)dealloc 
{ 
    [super dealloc]; 
    [recievedData release]; 
} 

@end 

正常情況下，它由於EXC_BAD_ACCESS（NSZombie不會檢測到任何東西）而崩潰。 我注意到，如果你打開connectionDidFinishLoadingself.recievedData.length只是self.recievedData，它不會崩潰，看起來像有一些數據在那裏。同樣的事情，我得到的self.networkConnection - 如果我只是打印self.networkConnection，它的確定，但如果我打印self.networkConnection.retainCount（例如，任何伊娃都會工作），它會崩潰與相同的信號。

我似乎無法把握問題的所在，我一直在尋找它安靜了一會兒，我會感謝一些幫助，這:)
TNX！

哦，我把它與此代碼：
DataFetcher *fetcher = [[DataFetcher alloc] init];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://www.google.com"]]; [fetcher fetchDataWithRequest:request]; [fetcher release]; [request release];

Answer 1

NSLog(@"%@", self.recievedData.length); 

這裏％@格式說明意味着你要登錄Objective-C的對象，而在實際工作你通過簡單的整數它 - 這會讓你的應用崩潰。將您的日誌更改爲

NSLog(@"%d", self.recievedData.length);