下載大量圖像時發生內存泄漏問題

我試圖在屏幕頂部向用戶下載多於600張圖像，並在屏幕上方顯示進度表。我使用淡入淡出層來屏蔽我的屏幕，以顯示活動和進度。下載大量圖像時發生內存泄漏問題

我收到之間的內存警告消息和應用程序崩潰。

我的步驟，以達到循環是：

在應用程序委託，我檢查第一核心數據錶針對其具有isImageAvailable布爾字段「0」值的所有行。
如果顯示我一些計數（比如說600），並且我用YES和NO選項顯示並提醒。
在是：[self performSelector：@selector（myDownload :) withObject：nil afterDelay：0.2];

在myDownload

NSOperationQueue *queue = [NSOperationQueue new]; 
// Create our NSInvocationOperation to call loadDataWithOperation, passing in nil 
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self 
                   selector:@selector(startUpdatingRecords:) object:nil]; 

// Add the operation to the queue 
[queue addOperation:operation]; 
[operation release]; 
[queue release];

在startUpdatingRecords：

-(void)startUpdatingRecords:(id)sender 
{  
[self performSelectorInBackground:@selector(updateProgressMeter:) withObject: [NSString stringWithFormat:@"%d",self.loopStartIndex]]; 

// Variable declarations    
CGSize newSizeLarge ; 
NSPredicate *predicate; 
NSMutableArray *MatchingID; 
Image_DB *data; 

// Cache Directory path 
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); 

NSData *responseData; // = [[NSData alloc]init] ; 

NSURL *url = [[[NSURL alloc]init] autorelease]; 
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc]init] autorelease]; 
UIImage *imgSelected_Large = [[[UIImage alloc]init] autorelease]; 

// Loop through all IDs 
for (int i = 0; i < [self.arrayOfID count]; i++) //for (int i = loopStart; i < loopEnd; i++) 
{ 
if (self.abortDownload) 
{   
    break; 
} 

NSString *documentsDirectory = [[[NSString alloc] initWithFormat:@"%@",[paths objectAtIndex:0]] autorelease]; 
documentsDirectory = [paths objectAtIndex:0]; 
documentsDirectory = [documentsDirectory stringByAppendingFormat:@"/ImageFolder"]; // Image folder path 

myClass *classObj = [self.arrayOfID objectAtIndex:i]; 

NSString *strURl = [[[NSString alloc] initWithFormat:@"%@%@", self.MyURL,recipeObj.recipeImageStr] autorelease]; 
//NSLog(@"URL = %@",strURl);   

url = [NSURL URLWithString:strURl]; 
request = [NSMutableURLRequest requestWithURL:url]; 
responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:NULL error:NULL]; // Get Image Data into NSData 

//imgSelected_Large = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:strURl]]]; 

NSLog(@"Download Count = %d",i+1); 

if (responseData != nil) 
{ 
    imgSelected_Large = [UIImage imageWithData:responseData]; 

    // Resizining image 
    newSizeLarge.width = 320;  
    newSizeLarge.height = 180;  

    imgSelected_Large = [self imageWithImage:imgSelected_Large scaledToSize:newSizeLarge]; // New sized image 
    NSData *dataPhoto; // no need to release it because UIImageJPEGRepresentation gives autoreleased NSData obj. 
    dataPhoto = UIImageJPEGRepresentation(imgSelected_Large, 0.6); // Set new image representation and its Compression Quality 

    documentsDirectory = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"Image_%d", classObj.nodeID]];    
    [dataPhoto writeToFile:documentsDirectory atomically:YES]; //Write file to local folder at default path 

    predicate = [NSPredicate predicateWithFormat: @"(image_ID = %d)",recipeObj.nodeID]; 
    MatchingID = [CoreDataAPIMethods searchObjectsInContext:@"Image_DB" :predicate :@"image_ID" :YES :self.managedObjectContext]; 

    // Setting flag variable for available image 
    for (int j = 0; j< [MatchingID count]; j++) 
    { 
     //Assign the Authors Records in Class Object and save to Database 
     data = (Image_DB*) [MatchingID objectAtIndex:j];     
     // data.image_large = dataPhoto; // Code for storing BLOB object to DB 
     data.extra_1 = @"1"; 
     //NSLog(@"Flag updated"); 
    } 
} 
// Exit out code 
if (i == [self.arrayOfID count] - 1 || i == [self.arrayOfID count]) // Its the last record to be stored 
{  
    NSError *error;    
    if (![self.managedObjectContext save:&error]) 
    { 
     // Handle the error... 
     NSLog(@"Error in updating %@",error); 
    } 

    self.isUpdateImageCalled = NO; 
    [self performSelectorOnMainThread:@selector(removeProgressMeter) withObject:nil waitUntilDone:NO]; 

} 
// Update UI screen while in downloading process 
[self performSelectorInBackground:@selector(updateProgressMeter:) withObject:[NSString stringWithFormat:@"%d",self.loopStartIndex+i+1]]; 
} 
}

如果我沒有釋放responseData然後我的應用程序顯示我記憶警告，並得到了墜毀。如果我發佈了，那麼[NSConcreteMutableData release]：發送消息發送到解除分配的實例0x1e931de0錯誤發生。

如何優化我的代碼。任何人都可以在我的代碼中建議我並重寫並製作精緻的代碼。

請幫我一把。

來源

2012-04-06 Lalit Paliwal

願這個鏈接可以幫助你！ http://stackoverflow.com/questions/3703734/downloading-large-amount-of-images-ipad-memory-leak – NSException 2012-04-06 07:42:32

您的responseData返回sendSynchronousRequest是autoreleased因此你不應該自己釋放它。對於第一眼，我沒有看到代碼中的內存泄漏。有可能您的應用程序實際上使用太多內存，而不會泄漏它。嘗試把一個自動釋放池的內部進行循環：

for (...) { 
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

    // your original code with a lot of autoreleased objects 

    [pool release]; 
}

如果一個自動釋放池內包裝你的代碼，所有發送包裹內autorelease消息的所有對象將被真正發佈的時候池本身是發佈：這種方式可以在每個循環中清除內存。

另請參閱文檔中的Using Autorelease Pools，它特別提到您應該在「如果您編寫創建許多臨時對象的循環」的情況下使用它們。

來源

2012-04-06 07:48:59 MrTJ

非常感謝，它爲我工作。再次感謝。 :) – 2012-04-06 08:33:42

下載大量圖像時發生內存泄漏問題

回答

相關問題