Right now I'm loading images view a file url and its taking a long time. I've even put it on the main thread as a high priority but its still slow. This is actually in a loop for like 6 images. My question is:
Is there a faster way to load images to a view than this? Like an alternative to a file url?
//check the filetype
if ([fileType isEqual: #"image"])
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
//get image
NSURL *imageFileUrl = [[NSURL alloc] initWithString:file.url];
NSData *imageData = [NSData dataWithContentsOfURL:imageFileUrl];
dispatch_async(dispatch_get_main_queue(), ^{
imageView.image = [UIImage imageWithData:imageData];
});
});
}
My images are at a quality of this preset and the size is the size of the iphone screen whether that be a 5,6,or 6 plus
self.camera = [[LLSimpleCamera alloc] initWithQuality:AVCaptureSessionPreset1280x720
position:CameraPositionBack
videoEnabled:YES];
thanks,
While there isn't any shortcut to loading the images there are things you can do to help.
Initially only load the image that are visible, after that load any that may be visible soon.
If the size of the image is larger than the view create a smaller image, perhaps a couple for different screen resolution devices.
Create a low resolution image versions, load them first to get something up for the user and then load the full resolution images replacing the low resolution version..
Please, Add the sizes of the images and the sizes of the UIImageView and screen resolution to the question.
What can I suggest you that,
Save the duplicate copy of each image in lower resolution/Size on
server.
Load the duplicate image on first load.
When user particularly views an image, load original image then.
Related
I am getting memory warning when loading large images, i have to cache the images also so that if the user will scroll up that image should be present. I am using SDWebImage Library.
cell!.productImageView?.sd_setImageWithURL(url)
According to your scenario I have two suggestions:
1. Generally recommended is that we can upload small size images on server so that we can avoid memory problems. A thumbnail or a small dimension sized image is considered if we are showing the images in a UITableView.However we can show larger image when we tap on a certain small image in UITableView and go to a detail view controller.
2. Secondly you can download the images and resize them and then use NSCache class to cache them rather using SDWebImage. As in your case imageWithContentsOfFile can't be used because you are downloading the images from some URL.However after download you can use imageWithContentsOfFile or you can resize images and use your own NSCache.
What are you using for display image on image view .UIImage imageNamed is maintain cache itself.
Please use below code.
[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"imageName" ofType:#"png"]];
This will helpful to you for manage memory consumptions.
Try this code.
NSString *thumbnailImage = objectname.thumbnailUrl;
[cell.productImageView sd_setImageWithURL:[NSURL URLWithString:thumbnailImage]];
My project is having image sharing functionality. In this functionality my app asks the user from which library you want to share.
I wrote below code to assign image, retrieved from Default library/Custom library.
Device default library
imgVwMediaFile.image = [UIImage imageWithCGImage:[asset thumbnail]; //(ALAsset *)asset
Custom library (images are at Documents/image/user)
imgVwMediaFile.image = [UIImage imageWithContentsOfFile:path];
//(NSString*)path
App displyas this images in collection view having custom cell.
When i select app custom library then images are retrieves from Documents directory ,but imagewithcontentofFile cosuming around 90 to 100 Mb memory.
In other case when i select app default libray, it is not cosuming more then 8 or 10 Mb memory.
I tried diffrent code from stack Q/A for custom library, but still memory issue is there.
-1-
CGImageRef iref = [[UIImage imageNamed:asset] CGImage] ;
imgVwMediaFile.image=[UIImage imageWithCGImage:iref];
iref=nil
-2-
NSData *imageData = [[NSData alloc] initWithContentsOfFile:path];
imgVwMediaFile.image=[UIImage imageWithData:imageData];
imageData=nil
-3-
imgVwMediaFile.image=[UIImage imageNamed:path];
So please guide me that, how can i load images from document dir ?
What are the best way to load images from document dir without increasing memory load ?
The problem is that yhe images you have saved to disk are large, so loading lots of the, to display in a collection takes a lot of memory. You use thumbnails from the built in library so you see a different result.
Ideally you would save a folder of thumbnails in your custom library and display those, then, when an image is selected, get the corresponding full size image to use (this is the approach basically all photo libraries use). Alternatively you can resize the images on-the-fly, but your scrolling is basically guaranteed to suck.
UIImage *img = [UIImage imageWithContentsOfFile:path];
What is the most efficient way to iterate over the entire camera roll, open every single photo and resize it?
My naive attempts to iterate over the asset library and get the defaultRepresentation results took about 1 second per 4 images (iPhone 5). Is there a way to do better?
I need the resized images to do some kind of processing.
Resizing full resolution photos is rather expensive operation. But you can use images already resized to screen resolution:
ALAsset *result = // .. do not forget to initialize it
ALAssetRepresentation *rawImage = [result defaultRepresentation];
UIImage *image = [UIImage imageWithCGImage:rawImage.fullScreenImage];
If you need another resolution you can still use 'fullScreenImage' since it has smaller size than original photo.
(CGImageRef)fullScreenImage
Returns a CGImage of the representation that is appropriate for
displaying full screen. The dimensions of the image are dependent on
the device your application is running on; the dimensions may not,
however, exactly match the dimensions of the screen.
In iOS 5 and later, this method returns a fully cropped, rotated, and
adjusted image—exactly as a user would see in Photos or in the image
picker.
Returns a CGImage of the representation that is appropriate for
displaying full screen, or NULL if a CGImage representation could not
be generated.
I have an app with 150 local images (about 500kb each). I have loaded them all into an array like this:
allPics = [[NSMutableArray alloc] init];
//NSString *imagePath;
NSArray *result = [database performQuery:#"SELECT image_path FROM validWords order by valid_word"];
for (NSArray *row in result) {
NSString *temp = [row objectAtIndex:0];
NSLog(#"%#", temp);
//imagePath = temp;
UIImage *newImage = [UIImage imageNamed:temp];
[allPics addObject:newImage];
}
When I set my UIImageView later to one of these pics, it hangs my interface up for a second, due to lazy loading from what I have read. I tried to prerender them, but that spiked my memory usage to over 3gb before it got a third of the way through my images. Should I be looking to use a background thread to render the image when I need it? When I reduced the image total to 4, once all 4 were rendered once, the transitions between them was seamless.
I appreciate any and all tips and solutions!
Yes, I would suggest a background thread and paging. If the user is looking at image 7, you should load images, say, 5,6,8 and 9. If the user then moves onto image 8, you can discard image 5 and lazy load image 10. This way the user sjhould be able to move through your images without a significant memory or performance overhead.
You can then also add heuristics such as 'if the user is paging through the images very quickly, don't load any images until they slow down',
Another tip is to store a very low resolution version of the image (say, a 50kb version) and store that at a different path. Then you can show the thumbnail images to the user and only lazy load in the high res image if the user stops on that image for a period of time.
Finally, be careful when you talk about image sizes. Is the 500KB compressed or uncompressed? If it is a 500KB compressed JPeg, the actual image on the device could be vastly bigger. A jpg with fairly uniform colour and a reasonably high level of compression can be very small on disk, but decompressed it could be a massive image. This could be another source of the lag you experience.
I have an NSManagedObject which has pictures that are stored somewhere like /var/mobile/Applications/.../.../uniqueIDforNSMO/Pictures/
I have no problem getting these pictures off the disk by finding them based on the NSMO's uniqueID, I have a DataController that will pull them for me, and that is very performant. But I run into issues when I try to add these pictures to a view, the UI becomes blocked. I suspect the problem is that these images are very high resolution (they are images from the iPad camera roll).
Displaying 5 images takes about 3 seconds, leaving the UI blocked. Displaying even just 2 images blocks the damn UI. Here's how I add them, on a background thread:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
UIImage *image = [self.photos objectAtIndex:index];
dispatch_async(dispatch_get_main_queue(), ^{
cell.imageView.image = image;
});
});
If I set the imageView.image without dispatching it takes even longer.
Could the problem be that the images are so large, while the cell's imageViews are only 150x150? Or is it because I only have a reference to the image at first, so the realization of the image is the slow part?
Can anyone suggest anything here? I have tried resizing the images before they are returned in the array and that did not help.
The problem is that the images are being lazily loaded - UIImage only loads the image into memory when it needs to be drawn. What you can do is eagerly load the image on a background thread:
Create a CGBitmapContextRef using UIGraphicsBeginImageContext
Draw the image into the context
Get a new image from the context using UIGraphicsGetImageFromCurrentImageContext
Pass the image back to the main thread
As they are high-resolution images, I would suggest that you should make persistent thumbnails cache for that. Generating thumbnail real-time every time would waste too much CPU time unnecessarily.