I have an app which requires downloading image asynchronously in base64 encoded string(server is returning the image in Base64 encoded format),I am using the AsyncImage view,but it seems that AsyncImageView library only accepts the url to download asynchronously.
Anyone having any idea how to go about this,if i will download all images at once an then i can pass that encoded string to
[self.imageView loadImageFromURL:[NSURL URLWithString:[EncodedString]]];
but this dosesn't make sense as all the image will be downloaded still in UIThread.
Please help.
Thanks..!!
You should look into Cocoa Helpers - it has SimpleHTTPLoader for async loading and ImageViewCached which does exactly what you need. You create not imageView, but ImageViewCached and just set URL for it. It does the rest for you.
But if you want to do it your way:
I don't guarantee that the code below is correct, but the whole idea is (i took it from working code and rewrote it to correspond your task. I used cocoa helpers for base64 decoding. You may use your own methods.
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
NSString *query = [NSString stringWithFormat:#"site.example/image.jpg"];
NSString *data = [[[NSString alloc] initWithContentsOfURL:[NSURL URLWithString:query] encoding:NSUTF8StringEncoding error:nil] autorelease];
theImage = [UIImage imageWithData:(rfc::from_base64(data))]
dispatch_sync(dispatch_get_main_queue(), ^{
self.imageview.image = theImage;}
});
});
P.S. for base64-encoded images you'd have to modify ImageViewCached for it to load and decode images.
Related
I am using this code for displaying the image from URL to UIImageview
UIImageView *myview=[[UIImageView alloc]init];
myview.frame = CGRectMake(50, 50, 320, 480);
NSURL *imgURL=[[NSURL alloc]initWithString:#"http://soccerlens.com/files/2011/03/chelsea-1112-home.png"];
NSData *imgdata=[[NSData alloc]initWithContentsOfURL:imgURL];
UIImage *image=[[UIImage alloc]initWithData:imgdata];
myview.image=image;
[self.view addSubview:myview];
But the problem is that its taking too long time to display the image in imageview.
Please help me...
Is there any method to fast the process...
Instead of dispatch_async, Use SDWebImage for caching the images.
This is best I have seen...
The problem of dispatch_async is that if you lost focus from image, it will load again. However SDWebImage, Caches the image and it wont reload again.
The answers given to me on my own question Understanding the behaviour of [NSData dataWithContentsOfURL:URL] inside the GCD block does makes sense.So be sure that if you use [NSData dataWithContentsOfURL:URL] inside the GCD(as many developers do these days) is not a great idea to download the files/images.So i am leaning towards the below approach(you can either use NSOperationQueue).
Load your images using [NSURLConnection sendAsynchronousRequest:queue:completionHandler: then use NSCache to prevent downloading the same image again and again.
As suggested by many developers go for SDWebimage and it does include the above strategy to download the images files .You can load as many images you want and the same URL won't be downloaded several times as per the author of the code
EDIT:
Example on [NSURLConnection sendAsynchronousRequest:queue:completionHandler:
NSURL *url = [NSURL URLWithString:#"your_URL"];
NSURLRequest *myUrlRequest = [NSURLRequest requestWithURL:url];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:myUrlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
{
if ([data length] > 0 && error == nil)
//doSomething With The data
else if (error != nil && error.code == ERROR_CODE_TIMEOUT)
//time out error
else if (error != nil)
//download error
}];
Use Dispatch queue to load image from URL.
dispatch_async(dispatch_get_main_queue(), ^{
});
Or add a placeholder image till your image gets load from URL.
I have a NSMutableArray where it stores url to a image. And this NSMutableArray is called userPic. From my server it only prints out the url: not JSON or anything, only the url.
I can see in the output in Xcode that it shows the url, but how to I get this url in userPic to a background? Im trying to addSubView with the image for a background.
If something is unclear, sorry about that. Just let me know.
Please try to use this one.And i think your URL at index 0 of your array.
NSURL *imgURL = [NSURL URLWithString:[userPic objectAtIndex:0]]; // put your particular index where your image url in your array...
NSData *imgData = [[NSData alloc]initWithContentsOfURL:imgURL];
UIImage *img = [UIImage imageWithData: imgData];
[newView setBackgroundColor:[UIColor colorWithPatternImage:img]]
Hello I would like to run a thread and check the current downloaded size of a file.
This is what I use
UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://lasp.colorado.edu/home/wp-content/uploads/2011/03/suncombo1.jpg"]]];
NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *jpegFilePath = [NSString stringWithFormat:#"%#/test.jpeg",docDir];
NSData *data2 = [NSData dataWithData:UIImageJPEGRepresentation(image, 1.0f)];//1.0f = 100% quality
[data2 writeToFile:jpegFilePath atomically:YES];
downloadStatus.text =[NSString stringWithFormat:#"size: %zd", malloc_size(data2)];
[image release];
I have also tried to change malloc_size(data2) into image but again it is not the real result. I know this does not have thread and do not check during the download process but what am I supposed to use here to see the file size?
A couple of observations:
Your question presumed that your attempts to retrieve the size of the NSData were failing. They are not. The correct way to get the size of a NSData is via length.
Your confusion, though, stems from a faulty assumption that taking an externally generated JPEG on a roundtrip through UIImage and UIImageJPEGRepresentation would yield the identical NSData. This would have been extraordinarily unlikely. There are too many different JPG settings that could have changed (see the JPEG Wikipedia page). We certainly don't know what settings that original file used. I know that UIImage and/or UIImageJPEGRepresentation changed the color space of the file. I'd wager it's doing a lot of other things, too.
So your results are correct. The original file was 2.6mb and the resulting file was 4.5mb. If you change the compressionQuality from 1.0 to 0.99, the resulting file is only 1.4mb! But if you want the original file, just save it first (like I do below).
Consider the following code which downloads the image file, saves it, loads it into a UIImage, re-extracts it via UIImageJPEGRepresentation, and saves another copy of the image:
// let's make filenames where we'll store the files
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *suncomboOrig = [documentsPath stringByAppendingPathExtension:#"suncombo1-orig.jpg"];
NSString *suncomboReprocessed = [documentsPath stringByAppendingPathExtension:#"suncombo1-reprocessed.jpg"];
// let's download the original suncombo1.jpg and save it in Documents and display the size
NSURL *url = [NSURL URLWithString:#"http://lasp.colorado.edu/home/wp-content/uploads/2011/03/suncombo1.jpg"];
NSData *data = [NSData dataWithContentsOfURL:url];
NSLog(#"original = %d", [data length]);
[data writeToFile:suncomboOrig atomically:NO];
// let's load that into a UIImage
UIImage *image = [UIImage imageWithData:data];
// let's extract data out of the image and write that to Documents, too, also logging the size of that
NSData *data2 = UIImageJPEGRepresentation(image, 1.0);
NSLog(#"reprocessed = %d", [data2 length]);
[data2 writeToFile:suncomboReprocessed atomically:NO];
What that does is it reports:
2012-12-13 22:30:39.576 imageapp[90647:c07] original = 2569128
2012-12-13 22:30:40.141 imageapp[90647:c07] reprocessed = 4382876
So the first file I saved (which I suspect is identical to what's on your server) was 2.5mb, and the file after doing a roundtrip to a UIImage and re-extracted via 4.3mb. If I look at the two files that the above code saved, I can confirm that these NSData sizes are correct.
My original answer was predicated on the presumption that the OP was either unable to retrieve the size of a NSData or that there was some subtle issue underlying the simple question (such as wanting to get the size before the download commenced). Anyway, I've expanded my answer above, but I'll keep my original answer for historical purposes:
Original Answer:
The NSData property length tells you how many bytes were downloaded. E.g. [data2 length].
If it's really big, you can use NSURLConnection to download it asynchronously, which, depending upon your web server, may provide total file size before the download commences in the method didReceiveResponse (with the expectedContentLength property in the NSHTTPURLResponse *response parameter).
The other nice thing about NSURLConnection downloading is that you don't have to load the entire file in memory as you're downloading it, but rather you can stream it directly to persistent storage, which is especially useful if you're downloading multiple large files at the same time. If you're downloading a reasonably sized file, using NSURLConnection to download is overkill, but it can be nice when downloading large files and you want a progress indicator (or want to get the file size before the download commences).
But if you just want to know how many bytes were downloaded to your NSData, use length.
You can just use the C FILE class to get the file size.
FILE * handle = fopen([jpegFilePath UTF8String], "r");
fseek(handle, EOF); // seek to end of file
int size = ftell(handle); // returns position in bytes
fclose();
Because you say "current" size and mention a thread, I'm guessing you're trying to determine the file size as it is received. In that case, you can get the thread for free from an NSURLConnection, and you can get the data size from the delegate methods as it's received...
Create an instance variable for the downloaded data:
#property (nonatomic, strong) NSMutableData *data;
Create and launch a connection:
NSURL *url = [NSURL URLWithString:#"http://lasp.colorado.edu/home/wp-content/uploads/2011/03/suncombo1.jpg"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
self.data = [NSMutableData data];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
Implement the required methods in NSURLConnectionDataDelegate. For your question, the special part is this:
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.data appendData:data];
NSUInteger bytesSoFar = [self.data length];
// you're on the app main thread here, so you can do something
// to the UI to indicate progress
downloadStatus.text = [NSString stringWithFormat#"size: %d", bytesSoFar];
}
A good doc on the rest of the protocol is here. When the connection is complete, you can create the image as you did with the dataWithContentsOfURL...
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
UIImage *image = [[UIImage alloc] initWithData:self.data];
downloadStatus.text = [NSString stringWithFormat#"size: %d", [self.data length]];
}
I have following code for loading image from url in xml parsing endElement method :
food.image=strVal;
NSData *data=[[NSData alloc]initWithContentsOfURL:[NSURL URLWithString:strVal]];
UIImage *image=[[UIImage alloc]initWithData:data];
food.myImage=image;
Although I am using this loaded images at the end of application,my application has to wait till all image get loaded. I supposed to use cache here but i am confused how to use the cache in this application. Is there any other way?
Try this code this will not create load on your main thread:-
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
dispatch_async(queue, ^{
NSData *data=[[NSData alloc]initWithContentsOfURL:[NSURL URLWithString:yourURL]];
UIImage *image=[[UIImage alloc]initWithData:data];
dispatch_sync(dispatch_get_main_queue(), ^{
[yourImageView setImage:image];
});
});
In order to improve the client/server behaviour, I'm looking for adapt my iphone client code to proceed ziped responses.
The server adapt the SOAP response ziped.
I was looking how to uncompress the response but didn't work for me.
The first solution I studied was the ZipArchive, explained here, solution (from minizip) but it is focus on filesystem compression.
And I just need to uncompress a NSString.
After that I checked this second approach:
NSData *decodedGzippedData = [NSData dataFromBase64String:encodedGzippedString];
NSData* unGzippedJsonData = [ASIHTTPRequest uncompressZippedData:decodedGzippedData];
NSString* unGzippedJsonString = [[NSString alloc] initWithData:unGzippedJsonData encoding:NSASCIIStringEncoding];
But didn't work for me, because in the actual version the NSData dataFromBase64String didn't exists.
Now I'm working with the third response of the previous question, anybody knows which library or framework I need to install in order to import Base64.h and NSData+Compression.h ¿? Used in this other potencial solution
The solution was the next.
Install the next libraries to your project:
Base64.h // You can find it here
NSData+Compression.h // You can find it here
Use the code of one of the previous solutions
#import "Base64.h"
#import "NSData+compression.h"
...
// decoding the base64 ziped message
Byte inputData[[stringValue lengthOfBytesUsingEncoding:NSUTF8StringEncoding]];
[[stringValue dataUsingEncoding:NSUTF8StringEncoding] getBytes:inputData];
size_t inputDataSize = (size_t)[stringValue length];
size_t outputDataSize = EstimateBas64DecodedDataSize(inputDataSize);
Byte outputData[outputDataSize];//prepare a Byte[] for the decoded data
Base64DecodeData(inputData, inputDataSize, outputData, &outputDataSize);
// inflate the original string using gzip
NSData *theData = [[NSData alloc] initWithBytes:outputData length:outputDataSize];
NSData* result = [theData gzipInflate];//make bigger==gunzip
// Return the result
return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];