EXC_BAD_ACCESS錯誤

我試圖讀取的圖像的EXIF數據，由用戶選擇。我正在使用ALAssetLibrary。到目前爲止，我已經成功地得到所需assetForURL:resultBlock:failureBlock:方法參考URL，但是當我試圖與參考URL做任何事情，我收到了EXC_BAD_ACCESS錯誤。EXC_BAD_ACCESS錯誤

的URL的NSLog，就在（正確的，因爲據我所知）字符串中使用它，結果前：

assets-library://asset/asset.JPG?id=1000000003&ext=JPG

我一直在試圖找出這但是，我似乎每次都會陷入死衚衕。我必須承認我是新來的Objective-C，所以請隨時批評我的代碼。

代碼（遠離完整的類，但我認爲它應該是足夠了）：

//Class_X.m 

-(void)readExifDataFromSelectedImage:(NSURL *)imageRefURL  
{ 
    void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *) = ^(ALAsset *asset) 
    { 
     NSLog(@"Test:Succes"); 
    }; 

    ALAssetsLibrary *myAssetLib; 
    NSLog(@"%@",imageRefURL); 
    [myAssetLib assetForURL:imageRefURL 
       resultBlock:ALAssetsLibraryAssetForURLResultBlock 
       failureBlock:^(NSError *error){NSLog(@"test:Fail");}]; 
} 

//Class_Y.m 
//This also conforms to the UIImagePickerControllerDelegate And the NavigationControllerDelegate protocols: 

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info 
{ 
    self.referenceURL = [info valueForKey:@"UIImagePickerControllerReferenceURL"]; 
    NSString *mediaType = [info 
         objectForKey:UIImagePickerControllerMediaType]; 
    [self dismissModalViewControllerAnimated:YES]; 
    if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) { 
     UIImage *selectedImage = [info objectForKey:UIImagePickerControllerOriginalImage]; 
     imageView.image = selectedImage; 
     btnNoPicture.hidden = YES; 
     btnSelectPicture.hidden = YES; 
     btnTakePicture.hidden = YES; 
     imageView.hidden = NO; 
     UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Use this image?" 
                 message:@"Are you sure you want to use this image?" 
                 delegate:self 
               cancelButtonTitle:@"No" 
               otherButtonTitles:@"Yes", nil]; 
     [alert show]; 
     [alert release]; 
    } 

} 


-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex 
{ 
    if (buttonIndex == 0) 
    { 
     //Do not use the selected image. 
     imageView.image = nil; 
     imageView.hidden = YES; 
     //Restart picking process 
    } 
    else 
    { 

     // I have an instance variable of type Class_X which i use 
     // throughout this class; let's call this variable "report". 
     // I also have the referenceURL stored as an instance variable. 
     [self.report readExifDataFromSelectedImage:self.referenceURL]; 
    } 

}

來源

2011-05-16 Uxxish

EXC_BAD_ACCESS是最常見的過度釋放的對象的（懸擺指針）的結果。由於庫異步操作，該方法readExifDataFromSelectedImage:返回之後執行的塊，所以imageRefURL可能已經在這一點上釋放。嘗試retain請求資產前的URL和release它在成功和失敗塊。

來源

2011-05-16 15:09:32 omz

乾杯，即清理我最初的錯誤。然而，這並創建調用readExifFromSelectedImage方法（當我無論怎麼解析的網址相同（EXC_BAD_ACCES）錯誤，甚至沒有一個硬編碼[NSURL URLWithString：@「資產庫：//asset/asset.JPG ID = 1000000003＆EXT = JPG「] 有關任何建議嗎？[self.report]對象是好的，不同的方法正常工作沒有錯誤。在此先感謝:) – Uxxish 2011-05-16 15:28:39

嗯，它看起來像myAssetLib是不確定的。你聲明變量，但不要給它賦值... – omz 2011-05-16 15:46:26

令人難以置信的是我如何忽略這一點。謝謝一堆！現在完美的工作！ – Uxxish 2011-05-16 15:48:37

EXC_BAD_ACCESS錯誤

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