下载大量图像时发生内存泄漏问题

我试图在屏幕顶部向用户下载多于600张图像，并在屏幕上方显示进度表。我使用淡入淡出层来屏蔽我的屏幕，以显示活动和进度。下载大量图像时发生内存泄漏问题

我收到之间的内存警告消息和应用程序崩溃。

我的步骤，以达到循环是：

在应用程序委托，我检查第一核心数据表针对其具有isImageAvailable布尔字段“0”值的所有行。
如果显示我一些计数（比如说600），并且我用YES和NO选项显示并提醒。
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]]; 
} 
}

如果我没有释放responseData然后我的应用程序显示我记忆警告，并得到了坠毁。如果我发布了，那么[NSConcreteMutableData release]：发送消息发送到解除分配的实例0x1e931de0错误发生。

如何优化我的代码。任何人都可以在我的代码中建议我并重写并制作精致的代码。

请帮我一把。

来源

2012-04-06 Lalit Paliwal

愿这个链接可以帮助你！ 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因此你不应该自己释放它。对于第一眼，我没有看到代码中的内存泄漏。有可能您的应用程序实际上使用太多内存，而不会泄漏它。尝试把一个自动释放池的内部进行循环：

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

    // your original code with a lot of autoreleased objects 

    [pool release]; 
}

如果一个自动释放池内包装你的代码，所有发送包裹内autorelease消息的所有对象将被真正发布的时候池本身是发布：这种方式可以在每个循环中清除内存。

另请参阅文档中的Using Autorelease Pools，它特别提到您应该在“如果您编写创建许多临时对象的循环”的情况下使用它们。

来源

2012-04-06 07:48:59 MrTJ

非常感谢，它为我工作。再次感谢。 :) – 2012-04-06 08:33:42

下载大量图像时发生内存泄漏问题

回答

相关问题