In my app, I have a bunch of different image packs to download. The images are downloaded from my website one by one. The packs contain anywhere from 100-1500 images and each image is about 100KB-200KB.
When downloading the images, I have a method that selects the images to download, then I have a second method that does the actual downloading based on parameters sent from the main method. Here is the code for the download method:
-(BOOL) downloadImageName:(NSString *)imageName ImageGroup:(NSString *)imageGroup AndRow:(int)row {
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *docsPath = [paths objectAtIndex:0];
NSURL *downloadURL = [NSURL URLWithString:[NSString stringWithFormat:#"http://www.website.com/%#_0001.jpg",imageName]];
NSData *data = [NSData dataWithContentsOfURL:downloadURL];
NSString *savePath = [NSString stringWithFormat:#"%#/%#^%#_%#.jpg",docsPath,currentServerCycle,imageGroup,imageName];
BOOL downloaded = [data writeToFile:savePath atomically:YES];
if (downloaded)
return YES;
}
else {
return NO;
}
}
The problem I am having is this:
When I run this with performance tools looking at allocations I'm seeing that the app is keeping mallocs (NSConcreteData) each time an image is downloaded and only releasing them when the main method (the one calling this download method) completes. Thats fine for the smaller image packs, but the larger ones are obviously crashing after my total allocations hit something like 300+MB (the normal amount of allocations in my app is about 3mb).
They arent leaking, because once the image pack is downloaded and the method ends, all the mallocs are gone.
I have tried manually allocing and releasing the NSData *data but it has no effect.
Perhaps the autorelease pool the objects are in is not being drained until the main method returns. You might try adding NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; at the beginning of your download method, then [pool drain]; right before you return from the download method. You need to make sure you release the pool before you return no matter where you return otherwise you'll leak the pool.
Also, just as a point of standard Objective-C style, your method should be named:
(BOOL)downloadImageName:(NSString *)imageName imageGroup:(NSString *)imageGroup andRow:(int)row
with lowercase letters to start the "imageGroup:" and "andRow:" argument names.
Related
I have an application which donwloads several images and stores them on the phone. In total it will probably required around 20 images tops. I need to be able to retrieve any of these images at will depending on what screen the user is on. These images will be stored indefinitely, so I don't want to use temp directory.
At present I have a class named Images with these methods
- (void) cacheImage: (NSString *) ImageURLString : (NSString *)imageName
{
NSURL *ImageURL = [NSURL URLWithString: ImageURLString];
// Generate a unique path to a resource representing the image you want
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex: 0];
NSString *docFile = [docDir stringByAppendingPathComponent: imageName];
// Check for file existence
if(![[NSFileManager defaultManager] fileExistsAtPath: docFile])
{
// The file doesn't exist, we should get a copy of it
// Fetch image
NSData *data = [[NSData alloc] initWithContentsOfURL: ImageURL];
UIImage *image = [[UIImage alloc] initWithData: data];
// Is it PNG or JPG/JPEG?
// Running the image representation function writes the data from the image to a file
if([ImageURLString rangeOfString: #".png" options: NSCaseInsensitiveSearch].location != NSNotFound)
{
[UIImagePNGRepresentation(image) writeToFile: docFile atomically: YES];
}
else if([ImageURLString rangeOfString: #".jpg" options: NSCaseInsensitiveSearch].location != NSNotFound ||
[ImageURLString rangeOfString: #".jpeg" options: NSCaseInsensitiveSearch].location != NSNotFound)
{
[UIImageJPEGRepresentation(image, 100) writeToFile: docFile atomically: YES];
}
}
}
- (UIImage *) getCachedImage : (NSString *)imageName
{
NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* cachedPath = [documentsDirectory stringByAppendingPathComponent:imageName];
UIImage *image;
// Check for a cached version
if([[NSFileManager defaultManager] fileExistsAtPath: cachedPath])
{
image = [UIImage imageWithContentsOfFile: cachedPath]; // this is the cached image
}
else
{
NSLog(#"Error getting image %#", imageName);
}
return image;
}
-(void)getImages
{
//example
NSString *image1URL = #"http://test/image1.png";
NSString *image2URL = #"http://test/image2.png";
NSString *image3URL = #"http://test/image3.png";
[self cacheImage:sLogo: #"Image1"];
[self cacheImage:sBlankNav: #"Image2"];
[self cacheImage:buttonLarge :#"Image3"];
}
-(void) storeImages
{
image1 = [self getCachedImage:#"Image1"];
image2 = [self getCachedImage:#"Image2"];
image3 = [self getCachedImage:#"Image3"];
}
So I use the code like this
Images *cache = [[Images alloc]init];
[cache storeImages];
The get images method is called once when the app first starts to get the images, it isn't called again after that, unless the images on the server are updated and I need to retrieve the updated ones.
The code works, but the problem is when I navigate to a screen that uses it, there is a very slight delay before the screen loads as it is loading the images.
My application is a tabbed application, so it begins on tab 1, I click tab 2 which implements the code, there will be a slight pause the first time it loads. It doesn't last very long, but it is noticeable and is very annoying. After that it is fine, as it is already loaded. However with navigation controller, every time you move from the first VC to the second VC, the method will be called again, so each time you navigate the delay will be there.
The images are not very big, biggest one is 68kb, others are much smaller than that. At present I am just testing with 5 images. Is there a more efficient way of storing and retrieving images, or am I doing something wrong with my code? I need to be able to retrieve these images without any noticeable delay in order for my application to remain fluid and not jerky or clunky.
Thanks in advance!!
You have two options to do the image loading work on a background thread - use Grand Central Dispatch or NSInvocationOperation. GCD might be considered the cleaner of the two:
dispatch_queue_t q = dispatch_get_global_queue(0, 0);
dispatch_queue_t main = dispatch_get_main_queue();
dispatch_async(q, ^{
//load images here
dispatch_async(main, ^{
// show on main thread here
});
});
you have delay because you're downloading data synchronously
// NSData *data = [[NSData alloc] initWithContentsOfURL: ImageURL];
Try some smart library like SDWebImage:
it lets you download image asynchronously while you still can display a local image (a proxy image). By the way, you still get cache image for free. So even if u are on local, you can still catch previously downloaded images
https://github.com/rs/SDWebImage
A must have
I want to be able to refresh a view from another class, but nothing I have tried is working. My application is a tabbed application with several tabs set up. I have a method called refresh in my ViewController1 class that looks like this
-(void)TestMe{
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"widgjson" ofType:#"json"];
NSData *myData = [NSData dataWithContentsOfFile:filePath];
NSString *responseString = [[NSString alloc] initWithData:myData encoding:NSUTF8StringEncoding];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex: 0];
NSString *docFile = [docDir stringByAppendingPathComponent: #"json.txt"];
[responseString writeToFile:docFile atomically:NO encoding:NSUTF8StringEncoding error:Nil];
[self loadView];
[self viewDidLoad];
}
This works fine. When the application first loads up, it loads a different json, then when I click this button it loads a new JSON and then updates the view. This is just temporary to test out refreshing. However if I try to call this method from another class, or from the AppDelegates ApplicationDidEnterForeground methods, nothing happens. I tried calling it like this
-(void)TestMe{
ViewController1 *vc = [[ViewController1 alloc] init];
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"widgjson" ofType:#"json"];
NSData *myData = [NSData dataWithContentsOfFile:filePath];
NSString *responseString = [[NSString alloc] initWithData:myData encoding:NSUTF8StringEncoding];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex: 0];
NSString *docFile = [docDir stringByAppendingPathComponent: #"json.txt"];
[responseString writeToFile:docFile atomically:NO encoding:NSUTF8StringEncoding error:Nil];
[vc loadView];
[vc viewDidLoad];
}
So why does this method not work from any other classes. All I want to is to be able to refresh a view from another class or when the application loads up, but just can't seem to find anything that works.
Would be very grateful if someone could point me in right direction!
EDIT: UPDATING TO CLARIFY
Okay, what I have done for the time being which I don't like is put this
exit(0);
Inside AppDelegates ApplicationDidEnterBackground. This works to an extent, but is not an ideal solution.
What I would like to have happen is that when application is opened again, the AppDelegate gets run again which sets up the tabs. The JSON pulled from the server can affect the order of the tabs which is why I need the AppDelegates ApplicationDidFinishLaunching method to reload itself again.
Also I would like to know can I do this from another class in the application. The first time my application is loaded it asks for the users phone number, which is sent to the server which then generates an PIN. After this is done, then I want the AppDelegate method to load up and begin setting up the tabs and the order etc.
To prevent your application running in the background (and so to force reloading when you exit and re-enter) you can set the UIApplicationExitsOnSuspend key to YES in your info.plist.
However, this is probably a bit drastic.
Your current code for refreshing from the application delegate is a non-starter because you are creating a new instance of the view controller rather than talking to one that is on the screen.
For this reason it is best not to involve your application delegate at all in the process.
Instead, your view controller can register itself as an observer for the UIApplicationDidBecomeActive notification, and do whatever it needs to itself. You would typically register for this notification on viewDidLoad, and unregister on viewDidUnload (since, by definition, if you have unloaded the view, you don't need to refresh it when the app comes back up!).
You would register as follows (using blocks here as they are the future):
Declare an ivar of type id to hold the observer object, let's call it becomeActiveObserver in this case. So, wherever you are declaring your ivars, add id becomeActiveObserver. Then, in viewDidLoad:
becomeActiveObserver = [[NSNotificationCenter defaultCenter]
addObserverForName:UIApplicationDidBecomeActive
object:nil
queue: nil
usingBlock:^(NSNotification *note){
//put your reloading code in here
[self TestMe];
}];
And remove like so in viewDidUnload:
[[NSNotificationCenter defaultCenter] removeObserver:becomeActiveObserver;
You can follow a similar pattern to pick up notifications (your own, or system ones) from anywhere else in your app. This is a better design than passing everything through the app delegate as it involves much looser coupling.
I guess clickMe is an action to a button.if you want to refresh the viewcontroller at startup then add a function in viewcontroller similar to clickme or any function that refreshes the view and call it from applicationWillEnterForeground method or you may try this :-
- (void)applicationWillEnterForeground:(UIApplication *)application
{
NSLog(#"app will enter foreground");
[viewController clickMe:NULL];
}
and you may change the file in the applicationWillEnterForeground method of appDelegate if your application requires.
I am attempting to save and load a UIImage to and from the iPhone documents directory after the image is picked from the iPhone Photo Library. It is able to do so, but for some reason, when I load the image, it rotates it 90 degrees counterclockwise. Here is my saveImage and loadImage methods:
Save Image:
- (void)saveImage: (UIImage*)image{
if (image != nil)
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithString: #"lePhoto.png"] ];
//NSData* data = UIImagePNGRepresentation(image);
//[data writeToFile:path atomically:YES];
[UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
}
}
Load Image:
- (NSData*)loadImage{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithString: #"lePhoto.png"] ];
NSData *data = [[NSData alloc] initWithContentsOfFile:path];
//UIImage *image = [[UIImage alloc] initWithData:data]; //my second try
//UIImage* image = [UIImage imageWithContentsOfFile:path]; //first try
//return image;
return data;
[data release];
}
And I am now loading the image like this, to see if it would, for some crazy reason, solve my problem (it didn't, obviously):
UIImage* theImage = [[UIImage alloc] initWithData:[self loadImage]];
I have done some testing where I have two UIImageViews side-by-side, one on the left that doesn't save and load the image before display (it just straight-up shows the image once a photo is picked from the ImagePicker), and one on the right that displays AFTER the save load occurs. The one on the right is the only one rotating 90 degrees CCW; the non Save/Load picture is displaying correctly. This only occurs on the actual iPhone. The simulator shows both images correctly. I have spent many, many hours attempting to figure it out, but to no avail. Any ideas as to what could be causing this?
EDIT: It should also be known that the image always says it's oriented up, even when it obviously isn't! It only rotates after ALL of the code has been run. I've tried doing a force redraw in between my code to see if that changes things, but it doesn't (though it is possible I'm even doing that wrong. Who knows, anymore).
Also, it will not autorotate photos that have been screenshot from the iPhone. Only photos that have been taken by the camera. [I haven't tried downloaded photos.] It's the weirdest thing...
And if you're wondering exactly how I'm pulling my picture, here's the method that will at least shed light on what I'm doing (it's not every method needed to do this function, obviously, but it gives insight on how I've written my code):
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
theimageView.image = [info objectForKey:#"UIImagePickerControllerOriginalImage"];
[self saveImage:[info objectForKey:#"UIImagePickerControllerOriginalImage"]];
[picker dismissModalViewControllerAnimated:YES];
}
Any advice is greatly appreciated. And I do know this much: if there's a way to do something crazy to get some stupid, never-before-heard-of problem, chances are, I'll find it, apparently :P
Ok. I figured it out. Apparently when you save things with PNG representation, and not JPEG representation, the image orientation information is not saved with it. Because of this, every image loaded will default to showing orientation up. So, the easiest way is to do this:
NSData* data = UIImageJPEGRepresentation(image,0.0);
[data writeToFile:path atomically:YES];
instead of this:
[UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
And, of course, changing all the picture names from .png to .jpg. The 0.0 part of the code above is to control Alpha levels, which is required of jpegs. Hope this helps people in the future!
I assume you're using the Assets Library Framework to get the image. If so, you'll want to get the orientation of the image in your results block, and manipulate the UIImage to adjust. I have something like the following:
ALAssetsLibraryAssetForURLResultBlock resultBlock = ^(ALAsset* asset)
{
ALAssetRepresentation* rep = [asset defaultRepresentation];
_orientation = rep.orientation;
...
}
Aside: What a great type name, huh? Holy moly, does Objective-C need namespaces!
Thanks so much...
This code has worked and saved several hours of work for me.
NSData* data = UIImageJPEGRepresentation(image,0.0);
[data writeToFile:path atomically:YES];
in the place of
[UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
I had the following code that takes in 14 mb or more of image data encoded in base4 string and converts them to jpeg before writing to a file in iphone. It crashes my program giving the following error :
Program received signal: “0”.
warning: check_safe_call: could not restore current frame
I tweak my program and it can process a few more images before the error appear again. My coding is as follows:
// parameters is an array where the fourth element contains a list of images in base64 >encoded string
NSMutableArray *imageStrList = (NSMutableArray*) [parameters objectAtIndex:5];
while (imageStrList.count != 0) {
NSString *imgString = [imageStrList objectAtIndex:0];
// Create a file name using my own Utility class
NSString *fileName = [Utility generateFileNName];
NSData *restoredImg = [NSData decodeWebSafeBase64ForString:imgString];
UIImage *img = [UIImage imageWithData: restoredImg];
NSData *imgJPEG = UIImageJPEGRepresentation(img, 0.4f);
[imgJPEG writeToFile:fileName atomically:YES];
[imageStrList removeObjectAtIndex:0];
}
I tried playing around with UIImageJPEGRepresentation and found out that the lower the value, the more image it can processed but this should not be the way. I am wondering if there is anyway to free up memory of the imageStrList immediately after processing each image so that it can be used by the next one in the line.
Your problem is that the UIImages and NSDatas are piling up in memory in a loop. Normally the autorelease pool would take care of this at the end of the event loop, but you're not letting it get that far. You have two choices:
Explicitly allocate/init and then release when done the UIImage and NSData objects, rather than using the +class methods.
Create an explicit autorelease pool inside the loop, and drain it at the end. Do this with:
NSAutoreleasePool * myPool = [[NSAutoreleasePool alloc] init];
[myPool release];
NSMutableArray *imageStrList = (NSMutableArray*) [parameters objectAtIndex:5];
while (imageStrList.count != 0) {
NSAutoReleasePool *pool = [[NSAutoReleasePool alloc] init];
NSString *imgString = [imageStrList objectAtIndex:0];
// Create a file name using my own Utility class
NSString *fileName = [Utility generateFileNName];
NSData *restoredImg = [NSData decodeWebSafeBase64ForString:imgString];
UIImage *img = [UIImage imageWithData: restoredImg];
NSData *imgJPEG = UIImageJPEGRepresentation(img, 0.4f);
[imgJPEG writeToFile:fileName atomically:YES];
[imageStrList removeObjectAtIndex:0];
[pool release];
}
You should create another autoreleasepool inside the loop because objects created inside loop won't be released until the program get out from the loop.
Auto release pool inside the loop will release all objects created inside the loop every time.
I seem to have a fundamental gap in my memory management understanding. The code below is located within a singleton that gets called multiple times within my app to parse data that is downloaded from the web. For each article I download, I allocate a mutable string, then do tons of parsing, then write the file to the file system for later display in a UIWebView.
But every time I enter this method, I allocate a new "articleString". And I never release this string. I think this is a leak, but if I add a release at the bottom of this method (after the file is written), my app crashes the next time this method is called. I don't understand why it crashes, since another NSMutableString is allocated next time it is called.
UPDATE: I do release articleString in the dealloc method. But it still seems that I should release at the end of this method, since I alloc every time I enter.
UPDATE: articleString is defined as follows in the header:
#property (nonatomic, retain) NSMutableString *articleString;
the parseArticle method below is a placeholder for a series of methods that manipulate articleString.
self.articleString = [[NSMutableString alloc] initWithData:articleData encoding:NSUTF8StringEncoding];
//Parse the article for display
[self parseArticle];
//Write the article string to a file for later display
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:#"article.html"];
NSLog(#"%#", articleString);
[articleString writeToFile:path atomically:YES];
I like to let properties handle this for me. If the articleString property is set to retain then this is simple.
self.articleString = [[[NSMutableString alloc] initWithData:articleData encoding:NSUTF8StringEncoding] autorelease];
[self doStuff];
Then
- (void)dealloc {
self.articleString = nil;
[super dealloc]
}
article string will get released and properly retain when you set a new one. And it will be cleaned up on dealloc.