Objective C: App getting Memory Warning Level 2 and exits shortly after

zaikshev88 · 06-11-2011, 04:35 AM

My app grabs photo images from a server and stores them in an array which will eventually be displayed in a UITableView Controller.

I am displaying 2 images in a single cell (768 by 768 pixels and 100 X 100 pixels).

At launch, the app will load 10 cells with images and the user can choose to load the next 10 photos using a "load more" button. Usually after 15-20 'load more' clicks, I will receive a memory warning level = 2 message and my app will just terminate.

Is this due to the fact that there are too many images displayed? How can I resolve this issue?

Domele · 06-11-2011, 04:38 AM

I don't have experience just from what I've read. Large images will consume a lot of memory. Unless the user is on an iPad there is not reason to have images that big. You also need to learn to lazy load more. Only load when you have to. Maybe someone who has displayed big images can talk to you more in depth about your situation.

zaikshev88 · 06-11-2011, 04:45 AM

Hi Domele, interesting thing is that I have already implemented lazy loading of my images. It still gives me a memory warning level 2 message

refreshe · 06-11-2011, 06:00 AM

Is your array of images always in memory? If it is, then you will eventually crash as it grows too large. When dealing with large images, you might want to save them to disk and load them as needed (when cells become visible) instead of having them all in memory at once. At the least, handle the memory warning by remove non-visible images from memory when it's triggered.

Duncan C · 06-11-2011, 09:43 AM

Quote:

Originally Posted by zaikshev88

My app grabs photo images from a server and stores them in an array which will eventually be displayed in a UITableView Controller.

I am displaying 2 images in a single cell (768 by 768 pixels and 100 X 100 pixels).

At launch, the app will load 10 cells with images and the user can choose to load the next 10 photos using a "load more" button. Usually after 15-20 'load more' clicks, I will receive a memory warning level = 2 message and my app will just terminate.

Is this due to the fact that there are too many images displayed? How can I resolve this issue?

When you click your "load more" button, how are you releasing the old images before loading new ones? You should probably post the relevant code.

Either you're keeping them in an array and not releasing them at all, or you have an extra retain (explicit or implicit) somewhere, and you are leaking the images. Try running your app with the leaks and memory allocation instruments. I bet you'll find that every time you click the more button, your memory usage grows, until you run out.

zaikshev88 · 06-11-2011, 10:36 AM

Hi basically I am using the code below to retrieve and store my photos. Every time I click 'load more', the array basically grows (with 10 photo objects more each time). Is there a way to control memory usage for this case? In fact I am only storing the profile image and not the actual sized photos (only URL stored)

Code:

- (void)preloadPhotoData
{   
    self.returnCount = 0;
    UIDevice *myDevice = [UIDevice currentDevice];
	NSString *deviceUDID = [myDevice uniqueIdentifier];
    
    self.urlString = [NSString stringWithFormat:@"http://myURL.com/photos.json?device_id=%@&page=%i&per_page=%i&type=%@",deviceUDID,self.pageNum,kPhotosPerPage,self.type];
    
    NSString *loadingString = [NSString stringWithFormat:@"Loading data from Instahotness....."];
    self.loadingPage.loadingTextLabel.text = loadingString;
    [self fetchJSONFile];
}

-(void)fetchJSONFile
{    
    NSURL *url = [NSURL URLWithString:self.urlString];
    
    __block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
    [request setCompletionBlock:^{
        
        // Use when fetching text data
        NSString *responseString = [request responseString];
        
        NSError *error;
        SBJsonParser *json = [[SBJsonParser new]autorelease];
        self.jsonArray = [json objectWithString:responseString error:&error];
        
        if (self.jsonArray == nil) 
        {
            NSString *errorString = [NSString stringWithFormat:@"JSON parsing failed: %@", [error localizedDescription]];
            NSLog(@"%@",errorString);
            [self errorHanding];        
        }
        else
        {
            NSString *createPhotoString = [NSString stringWithFormat:@"Loading Profile Pictures....."];
            self.loadingPage.loadingTextLabel.text = createPhotoString;
            [self createPhotoArray];
        }
        
        
    }];
    [request setFailedBlock:^{
        NSError *error = [request error];
        NSString *connectionErrString = [NSString stringWithFormat:@"Error Loading Profile Pic: %@", [error description]];
        NSLog(@"%@",connectionErrString);
        
        [self errorHanding];

    }];
    [request startAsynchronous];

}

-(void)createPhotoArray
{
    
    for (int i =0; i<[self.jsonArray count]; i++) 
    {
        NSDictionary *aPhoto = [self.jsonArray objectAtIndex:i];
        NSString *pid = [aPhoto valueForKey:@"pid"];
        NSString *userName = [aPhoto valueForKey:@"user_username"];
        NSString *userFullName = [aPhoto valueForKey:@"user_full_name"];
        NSString *userBio = [aPhoto valueForKey:@"user_bio"];
        NSString *caption = [aPhoto valueForKey:@"caption"];
        NSString *profileImageURL = [aPhoto valueForKey:@"user_profile_picture"];
        NSString *standardPhotoURL = [aPhoto valueForKey:@"standard_resolution"];
        NSString *isStarred = [aPhoto valueForKey:@"photoIsStarred"];
        NSString *thisStarCount = [aPhoto valueForKey:@"star_count"];
        
        BOOL photoIsStarred = [isStarred boolValue];
        NSUInteger starCount = [thisStarCount intValue];

        
        Photo *newPhoto = [[[Photo alloc]initWithPid:pid
                                            UserName:userName 
                                             userBio:userBio 
                                        userFullName:userFullName 
                                             caption:caption 
                                     profileImageURL:profileImageURL 
                                        profileImage:nil
                                      profilePicSize:CGSizeZero 
                                               image:standardPhotoURL 
                                           imageSize:CGSizeZero
                                      photoIsStarred:photoIsStarred
                                           starCount:starCount]autorelease];
        
        [self.photoArray addObject:newPhoto];  
    }
    
    [self fetchPhotoImage];

}

Domele · 06-11-2011, 10:47 AM

Use code tags please. [code] [/1CODE] Without the one.

Duncan C · 06-11-2011, 10:53 AM

Quote:

Originally Posted by zaikshev88

Hi basically I am using the code below to retrieve and store my photos. Every time I click 'load more', the array basically grows (with 10 photo objects more each time). Is there a way to control memory usage for this case? In fact I am only storing the profile image and not the actual sized photos (only URL stored)

- (void)preloadPhotoData
{
self.returnCount = 0;
UIDevice *myDevice = [UIDevice currentDevice];
NSString *deviceUDID = [myDevice uniqueIdentifier];

self.urlString = [NSString stringWithFormat:@"http://myURL.com/photos.json?device_id=%@&page=%i&per_page=%i&type= %@",deviceUDID,self.pageNum,kPhotosPerPage,self.ty pe];

NSString *loadingString = [NSString stringWithFormat:@"Loading data from Instahotness....."];
self.loadingPage.loadingTextLabel.text = loadingString;
[self fetchJSONFile];
}

-(void)fetchJSONFile
{
NSURL *url = [NSURL URLWithString:self.urlString];

__block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setCompletionBlock:^{

// Use when fetching text data
NSString *responseString = [request responseString];

NSError *error;
SBJsonParser *json = [[SBJsonParser new]autorelease];
self.jsonArray = [json objectWithString:responseString error:&error];

if (self.jsonArray == nil)
{
NSString *errorString = [NSString stringWithFormat:@"JSON parsing failed: %@", [error localizedDescription]];
NSLog(@"%@",errorString);
[self errorHanding];
}
else
{
NSString *createPhotoString = [NSString stringWithFormat:@"Loading Profile Pictures....."];
self.loadingPage.loadingTextLabel.text = createPhotoString;
[self createPhotoArray];
}

}];
[request setFailedBlock:^{
NSError *error = [request error];
NSString *connectionErrString = [NSString stringWithFormat:@"Error Loading Profile Pic: %@", [error description]];
NSLog(@"%@",connectionErrString);

[self errorHanding];

}];
[request startAsynchronous];

}

-(void)createPhotoArray
{

for (int i =0; i<[self.jsonArray count]; i++)
{
NSDictionary *aPhoto = [self.jsonArray objectAtIndex:i];
NSString *pid = [aPhoto valueForKey:@"pid"];
NSString *userName = [aPhoto valueForKey:@"user_username"];
NSString *userFullName = [aPhoto valueForKey:@"user_full_name"];
NSString *userBio = [aPhoto valueForKey:@"user_bio"];
NSString *caption = [aPhoto valueForKey:@"caption"];
NSString *profileImageURL = [aPhoto valueForKey:@"user_profile_picture"];
NSString *standardPhotoURL = [aPhoto valueForKey:@"standard_resolution"];
NSString *isStarred = [aPhoto valueForKey:@"photoIsStarred"];
NSString *thisStarCount = [aPhoto valueForKey:@"star_count"];

BOOL photoIsStarred = [isStarred boolValue];
NSUInteger starCount = [thisStarCount intValue];

Photo *newPhoto = [[[Photo alloc]initWithPid

id
UserName:userName
userBio:userBio
userFullName:userFullName
caption:caption
profileImageURL

rofileImageURL
profileImage:nil
profilePicSize:CGSizeZero
image:standardPhotoURL
imageSize:CGSizeZero
photoIsStarred

hotoIsStarred
starCount:starCount]autorelease];

[self.photoArray addObject:newPhoto];
}

[self fetchPhotoImage];

}

Your method createPhotoArray creates an array of Photo objects and saves it in self.photoArray. Presumably photoArray is a retained property, so that array is being retained. What does a Photo object contain?

You then call a method fetchPhotoImage. What does that method do? The name suggests that it loads photo images.

Where is the code that is actually loading the images from the server and installing them into your UIImageViews? That's where your memory problems are going to originate.

zaikshev88 · 06-11-2011, 10:57 AM

Hi Duncan, yes the code below basically retrieves the profile images from the server and stores them in the photo object. This is the only image I am storing. This array will then be used by the tableview controller for display. Can you advise me how I can store the profile images such that I do not cause memory issues?

Code:

-(void)fetchPhotoImage
{
    for (int i=0; i<[self.photoArray count]; i++) 
    {
        Photo *thisPhoto = [self.photoArray objectAtIndex:i];
        NSString *profileImageURL = thisPhoto.profileImageURL;
        
        NSURL *url = [NSURL URLWithString:profileImageURL];
        __block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
        [request setCompletionBlock:^{
            
            // Use when fetching binary data
            NSData *responseData = [request responseData];
            UIImage *profilePhotoImage = [UIImage imageWithData:responseData];
            thisPhoto.profileImage = profilePhotoImage;
            
            self.returnCount++;
            NSLog(@"Profile image %@", thisPhoto.profileImage);
            
            [self arrayIsComplete];
            
        }];
        [request setFailedBlock:^{
            NSError *error = [request error];
            NSString *connectionErrString = [NSString stringWithFormat:@"Connection failed: %@", [error description]];
            NSLog(@"%@",connectionErrString);
        }];
        [request startAsynchronous];
    }
}

Duncan C · 06-11-2011, 01:58 PM

Quote:

Originally Posted by zaikshev88

Hi Duncan, yes the code below basically retrieves the profile images from the server and stores them in the photo object. This is the only image I am storing. This array will then be used by the tableview controller for display. Can you advise me how I can store the profile images such that I do not cause memory issues?

Code:

-(void)fetchPhotoImage
{
    for (int i=0; i<[self.photoArray count]; i++) 
    {
        Photo *thisPhoto = [self.photoArray objectAtIndex:i];
        NSString *profileImageURL = thisPhoto.profileImageURL;
        
        NSURL *url = [NSURL URLWithString:profileImageURL];
        __block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
        [request setCompletionBlock:^{
            
            // Use when fetching binary data
            NSData *responseData = [request responseData];
            UIImage *profilePhotoImage = [UIImage imageWithData:responseData];
            thisPhoto.profileImage = profilePhotoImage;
            
            self.returnCount++;
            NSLog(@"Profile image %@", thisPhoto.profileImage);
            
            [self arrayIsComplete];
            
        }];
        [request setFailedBlock:^{
            NSError *error = [request error];
            NSString *connectionErrString = [NSString stringWithFormat:@"Connection failed: %@", [error description]];
            NSLog(@"%@",connectionErrString);
        }];
        [request startAsynchronous];
    }
}

I haven't used ASIHTTPRequest before. Can you set it up to download your images directly to files?

I would suggest reworking your code so you download each image and save it to a file in your documents directory. Save the filename in your Photo object.

Then make your table view load the image from a file and install the image in a table view cell after dequeuing/creating a cell (in your cellForRowAtIndexPath method) Set it up so only the table view cell's UIImageView retains the image. Then, when the cell scrolls offscreen and is reused, the old image will be released.