I have such code
arrayWithImages = [[NSMutableArray alloc] init];
NSEnumerator *enumForNames = [arrayWithNames objectEnumerator];
NSEnumerator *enumForURLs = [arrayWithURLs objectEnumerator];
id objName, objURL;
while(objName = [enumForNames nextObject]) {
objURL = [enumForURLs nextObject];
UIImageView *anImage = nil;
[anImage setImageWithURL:[NSURL URLWithString:objURL]];
(...)
[arrayWithImages addObject:anImage];
}
And each time I got SIGABRT in line with "[arrayWithImages addObject:anImage];"
What's here wrong?
I don’t see an setImageWithURL method on UIImageView. Where is this from?
Is there any output from the SIGABRT crash?
Try this code:
// Download the image
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:objURL]];
// Make an UIImage out of it
UIImage *anImage = [UIImage imageWithData:imageData];
// Create an image view with the image
UIImageView *imageView = [[UIImageView alloc] initWithImage:anImage];
// Check to make sure it exists
if (imageView != nil) {
// Add it to your array
[arrayWithImages addObject:imageView];
else {
NSLog(#"Image view is nil");
}
Note that you should download the images asynchronously to avoid hanging the loop. This blog post discussing asynchronous image downloading.
Also if you know that [enumForURLs nextObject]; will return an NSString (or even better, NSURL) you should assign objURL to type NSString (or NSURL).
Related
I created a class for download images from URLs for UITableViewCells (in this project I cannot use SDWebImageView or other codes from internet) but it looks like it's using a lot of memory and my tableview is not loading so fast. Can anybody point what is the problem?
Code:
//MyHelper class
+(NSString *)pathForImage:(NSString *)urlImageString{
if ([urlImageString class] == [NSNull class] || [urlImageString isEqualToString:#"<null>"] || [urlImageString isEqualToString:#""]) {
return #"";
}
NSArray *pathsInString = [urlImageString componentsSeparatedByString:#"/"];
NSString *eventCodeString = [pathsInString objectAtIndex:[pathsInString count] - 2];
NSString *imageNameString = [pathsInString lastObject];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cachePath = [paths objectAtIndex:0];
cachePath = [MyHelper validateString:[cachePath stringByAppendingString:eventCodeString]];
[cachePath stringByAppendingString:#"/"];
return [cachePath stringByAppendingString:imageNameString];
}
+(BOOL)imageExistsForURL:(NSString *)urlString{
if (!([urlString class] == [NSNull class]))
{
NSString *filePath = [MyHelper pathForImage:urlString];
NSFileManager *fileManager = [NSFileManager defaultManager];
return [fileManager fileExistsAtPath:filePath];
}
return false;
}
+(void)setAsyncImage:(UIImageView *)imageView forDownloadImage:(NSString *)urlString{
CGRect activityFrame = CGRectMake(0, 0, 60, 60);
UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithFrame:activityFrame];
activity.layer.cornerRadius = activity.frame.size.width / 2;
activity.clipsToBounds = YES;
activity.activityIndicatorViewStyle = UIActivityIndicatorViewStyleGray;
[imageView addSubview:activity];
[activity startAnimating];
dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(concurrentQueue, ^{
NSData *image;
if ([urlString class] == [NSNull class]) {
image = nil;
} else {
image = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:urlString]];
}
dispatch_async(dispatch_get_main_queue(), ^{
[activity stopAnimating];
[activity removeFromSuperview];
if (image)
{
[UIView animateWithDuration:0.9 animations:^{
imageView.alpha = 0;
imageView.image = [UIImage imageWithData:image];
imageView.alpha = 1;
}];
NSString *filePath = [MyHelper pathForImage:urlString];
NSError *error;
[image writeToFile:filePath options:NSDataWritingAtomic error:&error];
}
else
{
imageView.image = [UIImage imageNamed:#"icn_male.png"];
}
});
});
}
+(NSString *)validateString:(NSString *)string{
if (string == (id)[NSNull null] || string.length == 0 )
return #"";
return string;
}
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize;
{
float proportion;
if (image.size.height > image.size.width) {
proportion = image.size.height / newSize.height;
} else {
proportion = image.size.width / newSize.width;
}
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(newSize.width - (image.size.width/proportion),
newSize.height/2 - (image.size.height/proportion)/2,
image.size.width/proportion,
image.size.height/proportion)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Using this code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellIdentifier = #"MyCell";
MyCell *cell = (MyCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
if ([MyHelper imageExistsForURL:photoURLString ]) {
UIImage *image = [UIImage imageWithContentsOfFile:[MyHelper pathForImage:photoURLString]];
eventImageView.image = [MyHelper imageWithImage:image scaledToSize:CGSizeMake(60, 60)];
} else {
[MyHelper setAsyncImage:eventImageView forDownloadImage:photoURLString ];
}
}
Since it is now clear that you are using oversized images, the solution is to figure out how big your images need to be in order to look good in your app.
There are several courses of action depending on how much you can change the server side portion of your system.
Use an image that is optimally sized for the highest-res case (3x) and let 2x and 1x devices do the scaling. This is again a bit wasteful.
Create some scheme whereby you will be able to get the right size image for your device type (perhaps by appending 2x, 3x etc.) to the image file name. Arguably the best choice.
Do the resizing on the client side. This can be somewhat CPU intensive and is probably the worst approach in my opinion because you will be doing a lot of work unnecessarily. However, if you can't change how your server works, then this is your only option.
Another problem with your code is that you are doing the resizing on the main/UI thread, which is blocking your UI, which is a no-no. Never perform long operations on the main thread.
You should be doing it on a background thread using dispatch_async or perhaps NSOperation and a sequential queue to reduce memory usage. Note that this can create new problems because you have to update your image view when the image is ready and consider things such as whether the cell is still visible or not. I came across a nice blog post on this a while back so I suggest searching the web.
However, if the images are really huge, then maybe you could consider setting up a proxy server and then getting resized images from there instead of the main server. Of course, you would have to consider intellectual property issues in this case.
I have a screen that will load around 5 images, but they are huge images. Right now I use a
NSURLRequest
and a:
connectionDidFinishLoading
..for callback to tell me when each image is loaded.
The problem is that images would pop up one by one. Is there a way to have it display the image while it loads?
Thanks
The guts of what you need to do this are available as CGImageSource methods.
First, you use an asynchronous NSURLConnection to get the data. You add received data to a NSMutableData object as it arrives, so the data object gets bigger and bigger til finished.
You also create a progressive image source:
CGImageSourceRef imageSourcRef = CGImageSourceCreateIncremental(dict);
You will find lots of examples here and on google how to set the dictionary required.
Then as the data arrives, you pass the TOTAL data object into this method:
CGImageSourceUpdateData(imageSourcRef, (__bridge CFDataRef)data, NO); // No means not finished
You can then ask the image source for an image, which will be partial as the image is downloading. With a CGImage you can create a UIImage.
When you get the final data, you update the image source on last time:
CGImageSourceUpdateData(imageSourcRef, (__bridge CFDataRef)data, YES);
You then use the image source to get a final image and you're done.
Displaying it while loading ,I don't think UIImageView can load UIImageswith incomplete data while loading.I will go for
AsyncImageView ,
It can deal with all the burden of loading image asynchronous.Also UIActivityIndicator is already added to it.So it will be more user friendly
Use blocks and GCD's dispatch_async method.
Look at this example:
//communityDetailViewController.h
#interface communityDetailViewController : UIViewController {
UIImageView *imgDisplay;
UIActivityIndicatorView *activity;
// the dispatch queue to load images
dispatch_queue_t queue;
}
#end
//communityDetailViewController.m
- (void)loadImage
{
[activity startAnimating];
NSString *url = #"URL the image";
if (!queue) {
queue = dispatch_queue_create("image_queue", NULL);
}
dispatch_async(queue, ^{
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *anImage = [UIImage imageWithData:data];
dispatch_async(dispatch_get_main_queue(), ^{
[activity stopAnimating];
activity.hidden = YES;
if (anImage != nil) {
[imgDisplay setImage:anImage];
}else{
[imgDisplay setImage:[UIImage imageNamed:#"no_image_available.png"]];
}
});
});
}
You can subclass UIImageView and use this.
-(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
imageData = [NSMutableData data];
imageSize = [response expectedContentLength];
imageSource = CGImageSourceCreateIncremental(NULL);
}
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
[imageData appendData:data];
CGImageSourceUpdateData(imageSource, (__bridge CFDataRef)imageData, ([imageData length] == imageSize) ? true : false);
CGImageRef cgImage = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL);
if (cgImage){
UIImage* img = [[UIImage alloc] initWithCGImage:cgImage scale:1.0f orientation:UIImageOrientationUp];
dispatch_async( dispatch_get_main_queue(), ^{
self.image = img;
});
CGImageRelease(cgImage);
}
}
In my application I save images to an album as assets. I want also to retrieve them and display them in full screen. I use the following code :
ALAsset *lastPicture = [scrollArray objectAtIndex:iAsset];
ALAssetRepresentation *defaultRep = [lastPicture defaultRepresentation];
UIImage *image = [UIImage imageWithCGImage:[defaultRep fullScreenImage]
scale:[defaultRep scale] orientation:
(UIImageOrientation)[defaultRep orientation]];
The problem is that the image returned is nil. I have read at the ALAssetRepresentation reference that when the image does not fit it is returned nil.
I put this image to an UIImageView which has the size of the iPad screen. I was wondering if you could help me with this issue?
Thank you in advance.
I'm not a fan of fullScreenImage or fullResolutionImage. I found that when you do this on multiple assets in a queue, even if you release the UIImage immediately, memory usage will increase dramatically while it shouldn't. Also when using fullScreenImage or fullResolutionImage, the UIImage returned is still compressed, meaning that it will be decompressed before being drawn for the first time, thus on the main thread which will block your UI.
I prefer to use this method.
-(UIImage *)fullSizeImageForAssetRepresentation:(ALAssetRepresentation *)assetRepresentation
{
UIImage *result = nil;
NSData *data = nil;
uint8_t *buffer = (uint8_t *)malloc(sizeof(uint8_t)*[assetRepresentation size]);
if (buffer != NULL) {
NSError *error = nil;
NSUInteger bytesRead = [assetRepresentation getBytes:buffer fromOffset:0 length:[assetRepresentation size] error:&error];
data = [NSData dataWithBytes:buffer length:bytesRead];
free(buffer);
}
if ([data length])
{
CGImageSourceRef sourceRef = CGImageSourceCreateWithData((__bridge CFDataRef)data, nil);
NSMutableDictionary *options = [NSMutableDictionary dictionary];
[options setObject:(id)kCFBooleanTrue forKey:(id)kCGImageSourceShouldAllowFloat];
[options setObject:(id)kCFBooleanTrue forKey:(id)kCGImageSourceCreateThumbnailFromImageAlways];
[options setObject:(id)[NSNumber numberWithFloat:640.0f] forKey:(id)kCGImageSourceThumbnailMaxPixelSize];
//[options setObject:(id)kCFBooleanTrue forKey:(id)kCGImageSourceCreateThumbnailWithTransform];
CGImageRef imageRef = CGImageSourceCreateThumbnailAtIndex(sourceRef, 0, (__bridge CFDictionaryRef)options);
if (imageRef) {
result = [UIImage imageWithCGImage:imageRef scale:[assetRepresentation scale] orientation:(UIImageOrientation)[assetRepresentation orientation]];
CGImageRelease(imageRef);
}
if (sourceRef)
CFRelease(sourceRef);
}
return result;
}
You can use it like this:
// Get the full image in a background thread
dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
UIImage* image = [self fullSizeImageForAssetRepresentation:asset.defaultRepresentation];
dispatch_async(dispatch_get_main_queue(), ^{
// Do something with the UIImage
});
});
I'm very new to programming, and I jumped right into a project (I know thats not the smartest thing to do, but I'm learning as I go). The app that I'm writing has 10 UIImageViews that display a picture from the users camera roll. The code I'm using needs each of the UIImageViews to have tags. I'm currently using NSData to save the array images, and it works great, but I can't use this method anymore because NSData doesn't support the use of tags. I also can't use NSUserDefaults, because I can't save images to a plist. Here is how I'm attempting to do this (using the NSData method, which works but I have to edit this so that my tags work.)
This is my current code:
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img editingInfo:(NSDictionary *)editInfo {
if (imageView.image == nil) {
imageView.image = img;
[self.array addObject:imageView.image];
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
if (imageView2.image == nil) {
imageView2.image = img;
NSLog(#"The image is a %#", imageView);
[self.array addObject:imageView2.image];
[picker dismissModalViewControllerAnimated:YES];
[self.popover dismissPopoverAnimated:YES];
return;
}
...
- (void)applicationDidEnterBackground:(UIApplication*)application {
NSLog(#"Image on didenterbackground: %#", imageView);
[self.array addObject:imageView.image];
[self.array addObject:imageView2.image];
[self.user setObject:self.array forKey:#"images"];
[user synchronize];
}
- (void)viewDidLoad
{
self.user = [NSUserDefaults standardUserDefaults];
NSLog(#"It is %#", self.user);
self.array = [[self.user objectForKey:#"images"]mutableCopy];
imageView.image = [[self.array objectAtIndex:0] copy];
imageView2.image = [[self.array objectAtIndex:1] copy];
UIApplication *app = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationDidEnterBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:app];
[super viewDidLoad];
}
Any help or suggestions on how to edit this code so that I can save the images, while using tags is much appreciated, thanks!
EDIT: Here is my updated code:
-(IBAction)saveButtonPressed:(id)sender {
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES) objectAtIndex:0];
for (UIImageView *imageView in self.array) {
NSInteger tag = self.imageView.tag;
UIImage *image = self.imageView.image;
NSString *imageName = [NSString stringWithFormat:#"Image%i.png",tag];
NSString *imagePath = [docsDir stringByAppendingPathComponent:imageName];
[UIImagePNGRepresentation(image) writeToFile:imagePath atomically:YES];
}
NSLog(#"Saved Button Pressed");
}
- (void)applicationDidEnterBackground:(UIApplication*)application {
}
-(void)viewDidLoad {
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES) objectAtIndex:0];
NSArray *docFiles = [[NSFileManager defaultManager]contentsOfDirectoryAtPath:docsDir error:NULL];
for (NSString *fileName in docFiles) {
if ([fileName hasSuffix:#".png"]) {
NSString *fullPath = [docsDir stringByAppendingPathComponent:fileName];
UIImage *loadedImage = [UIImage imageWithContentsOfFile:fullPath];
if (!imageView.image) {
imageView.image = loadedImage;
} else {
imageView2.image = loadedImage;
}
}
}
}
You need to use "Fast Enumeration" to parse the array's objects, and write each object to disk sequentially. First, you're going to need to add the UIImageView objects to the array instead of the UIImage property of the UIImageView, so you can recover the tag. So instead of writing
[self.array addObject:imageView.image];
It will be
[self.array addObject:imageView];
Try to follow along with my code. I inserted comments on each line to help.
-(void)applicationDidEnterBackground:(UIApplication *)application {
//Obtain the documents directory
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainmask,YES) objectAtIndex:0];
//begin fast enumeration
//this is special to ObjC: it will iterate over any array one object at a time
//it's easier than using for (i=0;i<array.count;i++)
for (UIImageView *imageView in self.array) {
//get the imageView's tag to append to the filename
NSInteger tag = imageView.tag;
//get the image from the imageView;
UIImage *image = imageView.image;
//create a filename, in this case "ImageTAGNUM.png"
NSString *imageName = [NSString stringWithFormat:#"Image%i.png",tag];
//concatenate the docsDirectory and the filename
NSString *imagePath = [docsDir stringByAppendingPathComponent:imageName];
[UIImagePNGRepresentation(image) writeToFile:imagePath atomically:YES];
}
}
To load the images from disk, you'll have to look at your viewDidLoad method
-(void)viewDidLoad {
//get the contents of the docs directory
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainmask,YES) objectAtIndex:0];
//Get the list of files from the file manager
NSArray *docFiles = [[NSFileManager defaultManager]contentsOfDirectoryAtPath:docsDir error:NULL]);
//use fast enumeration to iterate the list of files searching for .png extensions and load those
for (NSString *fileName in docFiles) {
//check to see if the file is a .png file
if ([fileName hasSuffix:#".png"]) {
NSString *fullPath = [docsDir stringByAppendingPathComponent:fileName];
UIImage *loadedImage = [UIImage imageWithContentsOfFile:fullPath];
//you'll have to sort out how to put these images in their proper place
if (!imageView1.image) {
imageView1.image = loadedImage;
} else {
imageView2.image = loadedImage;
}
}
}
}
Hope this helps
One thing you need to be aware of is that when an app enters the background it has about 5 seconds to clean up its act before it's suspended. The UIPNGRepresentation() function takes a significant amount of time and is not instantaneous. You should be aware of this. It would probably be better to write some of this code in other places and do it earlier than at app backgrounding. FWIW
You can use the [NSbundle Mainbundel] to store that images.
To get path
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
First, there's still a problem in your for loop.
for (UIImageView *imageView in self.array) {
NSInteger tag = self.imageView.tag;
UIImage *image = self.imageView.image;
// ...
}
Before you make any other changes, you must understand why. imageView is your for loop control variable, which changes on each iteration through the loop. self.imageView is a different thing. It is the first of the 10 imageViews attached to your viewController. Every time this loop cycles, it looks at the first imageView, and only the first.
As for why saving doesn't work, it's probably because the arrays elsewhere aren't working. Add some logging to make sure there's something in the array, and that it has as many elements as you expect.
-(IBAction)saveButtonPressed:(id)sender {
NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES) objectAtIndex:0];
// Log to make sure the views expected have previously been stored.
// If the array is empty, or shorter than expected, the problem is elsewhere.
NSLog(#"Image view array before saving = %#", self.array);
for (UIImageView *imageViewToSave in self.array) {
NSInteger tag = imageViewToSave.tag;
UIImage *image = imageViewToSave.image;
NSString *imageName = [NSString stringWithFormat:#"Image%i.png",tag];
NSString *imagePath = [docsDir stringByAppendingPathComponent:imageName];
// Log the image and path being saved. If either of these are nil, nothing will be written.
NSLog(#"Saving %# to %#", image, imagePath);
[UIImagePNGRepresentation(image) writeToFile:imagePath atomically:NO];
}
NSLog(#"Save Button Pressed");
}
I've come across a weird issue that I've spent ages working on.
I'm basically trying to get the filepath of a photo out of the asset library and draw it on a pdf using the CGRectMake method using the code below:
In the .h file:
#property (strong, nonatomic) UIImage *pdfSnagImage;
In the .m file:
NSURL *url = [[NSURL alloc] initWithString:pdf.photo];
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library assetForURL:url resultBlock:^(ALAsset *asset) {
ALAssetRepresentation *rep = [asset defaultRepresentation];
self.filename = [rep filename];
NSLog(#"filename for image is: %#", self.filename);
CGImageRef iref = [rep fullResolutionImage];
if (iref) {
self.pdfImage = [UIImage imageWithCGImage:iref];
NSLog(#"image height %f", self.pdfImage.size.height);
}
} failureBlock:^(NSError *error) {
NSLog(#"Couldn't load asset %# => %#", error, [error localizedDescription]);
}];
UIImage *testImage = self.pdfImage;
[testImage drawInRect:CGRectMake( (pageSize.width - testImage.size.width/2)/2, 350, testImage.size.width/2, testImage.size.height/2)];
What's happening is that the UIImage after the block, testImage is actually being resolved before the block - therefore it is Null, as self.pdfImage is only set within the block.
If I put those lines of code in the block I get an error with the CGRectMake method, Invalid Context 0x0.
How on earth can I assign the self.pdfImage UIImage first then draw it?
The block is executed asynchronously...it's being executed on a separate thread. This is the design of the assets lib api.