I am loading images of size 1800x1300 in UIImage.(getting the images from server..)then i am adding that images into Uiscrollview.while scrolling my images ,the app getting crashed.is it a the image size issue.....?thanks in advance.
UIImage *image = [UIImage imageNamed:#"image.png"];
NSData *imgData = UIImageJPEGRepresentation([UIImage imageWithCGImage:[image CGImage]],0.5);
UIImage *compressedImage = [UIImage imageWithData:mgData];
You should definitely scale your images down, significantly, especially for the iPhone screen size.
You should also compress your images as much as you can without affecting the quality. Your image, I am assuming is somewhere around 1.5MB - 2MB, so that will use up an extreme amount if memory, and cause your device to crash every time.
Related
I have image files of dimension 1900x1200. In my code I try to load it as
UIImage *image = [UIImage imageNamed:imageName];
When I try to run this code in iPhone Simulator (Retina Display) my images look out of proportion. I tried to print
image.size.width and image.size.height
and the value I get is 950x600.
What I am doing wrong. Please help me out.
The answer is actually simple: the UIImageView (and the underlying UIImage) are using scale factor 2.0. That is your 1900x1200 pixels image correspond to 950x600 points image with scale factor 2 on retina display. You can double check the UIImage's scale property.
i load data in a tableview, each row have a simple picture 500x300px that go resize to size of cell.
Is possible resize the images?
tableview.m
NSString *filePath = [[NSBundle mainBundle] pathForResource:receip.image ofType:#"jpg"];
UIImage *image = [UIImage imageWithContentsOfFile:filePath];
cell.imageView.image = image;
I assume you mean resize them before putting them in the cell to improve performance?
You can do this with core graphics as follows:
//define desired size
CGSize size = CGSizeMake(100.0f, 100.0f);
//create drawing context
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
//draw image at new size
[image drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];
//capture resultant image
UIImage *resizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Be warned though that is a computationally expensive task. You'll probably want to resize all your images in advance, possibly on a background thread, and store the resized versions in an array. You definitely do not want to stick the code above in your cellForRowAtIndexPath method, or your table scrolling performance will be diabolical.
If those images come from an external source (say the web). It's better to first cache the original file and then (like explained by #Nick Lockwood) resize them (remember retina displays need twice the width / height for hi-res displaying). And after that process is complete you can send a signal that the "download" is complete and carry on showing the UITableView
If you already have the images in your app bundle I suggest you make a thumb version of that and add it to your bundle. For better performance o'course.
I have make a one small image and in which one detail page is there.
and I in detail page I have one image tag which is in webview with html page.
It's work completely but image take a much time for loading and show in the screen.
So how can I reduce the time of loading for image. and this image is come form url.
imgBiteSpot.clipsToBounds=YES;
NSData *imageData = [[[NSData alloc]init]autorelease];
imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:ObjBitSpot.StrImagePath]];
if(imageData==0)
{
imgBiteSpot.image=[UIImage imageNamed:#"img-not-found.gif"];
}
else {
UIImage *imgs = [[UIImage alloc] initWithData:imageData];
UIGraphicsBeginImageContext(CGSizeMake(88,88));
[imgs drawInRect:CGRectMake(0.0, 0.0, 88.0, 88.0)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imgBiteSpot.image=newImage;
[imgs release];
}
You could consider not downloading the image but downloading a one characters variable/flag from a web service. Depending on the answer from the web service you could load an image locally from the bundle? This could be faster.
Chris.
This is best example for loading image.
http://www.dimzzy.com/blog/2009/11/remote-image-for-iphone/
Its take time base on image size and internet speed.
But one thing you can do in your application.
You can download asynchronously that image and store it in temporary variable before you go in detail image view. When you go on that detail image you can load that downloaded image as per your requirement.
I am loading images into a UIImage with the values of a slider (these are pages or slides, if you like). This UIImage switches them very fast with the use of a slider. Problem is, at some point, the app crashes on the device with an error of:
2011-04-02 17:39:01.836 Book1[2123:307] Received memory warning. Level=1
Here's the code:
- (IBAction)slidePages:(id)sender{
int sliderValue = pageSlider.value;
NSString *slideToPage = [NSString stringWithFormat:#"P%i.jpg", sliderValue];
imagePlaceholder.image = [UIImage imageNamed:slideToPage];
pageDisplay.text = [NSString stringWithFormat:#"Page %i", sliderValue];
currentPage = sliderValue;
}
Is there anything I could do to make it more efficient? Maybe the error is somewhere else but I'm guessing it has to do with the fast loading of images.
Still, I don't know how iOS deals with this. Every time I load a new image into the UIImage what happens with the "unloaded" one?
Thanks in advance.
One imortant aspect of [UIImage imageNamed] is that it caches all images loaded in that way and they never get unloaded, even if you dealloc the UIImage that was created! This is good in some circumstances (e.g. smallish images in UITableView cells), but bad in others (e.g. large images).
The solution is to use [UIImage imageWithData] which does not do this caching and which unloads the data when the UIImage is dealloc'd.
More info and discussion here:
Difference between [UIImage imageNamed...] and [UIImage imageWithData...]?
Update
This question has some good info on the question of [UIImage imageNamed:] not emptying its cache when a memory warning occurs.
[UIImage imageNamed:] caches images, so every image thus loaded effectively leaks. I don't know what the canonical solution is, but one option might be to load the image with CGImageCreateWithJPEGDataProvider() and initialise it with [UIImage imageWithCGImage:].
The original (wrong) answer:
You may need to release the previous image before loading the current one.
Loading a bunch of large images in iOS has always been a memory issue. As Marcelo mentioned, you should only keep around images are you currently viewing. All other images should be released so they can be garbage collected and the memory freed up. In my experience, even loading 2 fairly large images (500k-2mb each) will cause memory issues, especially on older devices with less RAM.
I'm loading a 2400x1845 png image into a scroll view. The program crashes out of memory, is there a better way to handle this? mapScrollView is an UIScrollView in IB, along with a couple of UIButtons.
-(void)loadMapWithName:(NSString *)mapName
{
NSString* bundlePath = [[NSBundle mainBundle] bundlePath];
UIImage *image = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:#"%#/path/%#", bundlePath, [maps objectForKey:mapName]]];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
CGSize imgSize = image.size;
mapScrollView.contentSize = imgSize;
[mapScrollView addSubview:imageView];
[imageView release];
[self.view addSubview:mapScrollView];
}
UIImages are limited to 1024x1024 on the iPhoneOS. If you want to get around this, I think the only way is to make use of a CATiledLayer.
I don't know (exactly) how accurate this is, but I often use 64 MB physical memory as a guideline when targeting the iPhone OS (therefore attempting to restrict usage to half that amount). Having said that: The raw allocation size is not the issue.
You may be able to work around the issue by using CGImageRef (the lower level opaque image type) -- essentially wrapped by UIImage.
As another poster has stated, the example exceeds the maximum allowed image size. No device (iPhone/iPod) supports images of that scale, so resizing/dividing may be worth consideration.