How does one load or fetch an image that was saved to disk?
I wrote the image to the documents filepath using NSData and a PNG representation. How does one get this image back? UIImage.
UIImage *theImage = [UIImage imageWithContentsOfFile:filePath];
As ever, see the UIImage documentation at Apple. It is your friend.
Related
I am making a small application where I am receiving images from web-service. I am getting the image url. And the format of images is different different like .jpg,.gif,.png etc. And I want to save these images into my sandbox and later on show it into image view.
To do this I am giving a self name and gave the extension to .png. But at the time of retrieving the .png images are shown but different one's are not shown. So can you give me any idea how to convert all images to .png format or any other approach to do this?
after you retrieve your images/url save them this way:
NSData *imageData = UIImagePNGRepresentation(image);
[imageData writeToFile:savedImagePath atomically:YES];
Would it not be easier if you use an image library like SDWebImage which handles all the asynchronous image downloading and caching of the image onto your device?
https://github.com/rs/SDWebImage
Then you can do something like:
[myImageView setImageWithURL:[NSURL URLWithString:#"http://www.domain.com/path/to/image.jpg"]
placeholderImage:[UIImage imageNamed:#"placeholder.png"]];
I'm trying to download an image from the internet. I'm not sure why this code is not working when I want to get the photos with these specs (209x209 pixels,not more than 65KB).
Writing to iPhone directory:
NSData *imgAsData = [NSData dataWithContentsOfURL:imageURL];
UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:imageURL]];
//UIImage *image = [UIImage imageWithData:[NSData thumnail_url]];
NSFileHandle* myFileHandle = [NSFileHandle fileHandleForWritingAtPath:self.product.img_url];
[myFileHandle writeData:UIImagePNGRepresentation(image)];
[myFileHandle closeFile];
I even tried writeToFile, but it still doesn't work.
[imgAsData writeToURL: [NSURL URLWithString:self.product.img_url] atomically:YES];
Reading from iPhone directory:
NSFileHandle* myFileHandle = [NSFileHandle fileHandleForReadingAtPath:self.product.img_url];
//NSFileHandle* myFileHandle = [NSFileHandle fileHandleForReadingAtPath:self.product.thumbnail_url];
UIImage* loadedImage = [UIImage imageWithData:[myFileHandle readDataToEndOfFile]];
I was using this code in the same app to download thumbnails and they are working (notice the commented out lines using the "thumbnail_url"). I tried to substitute the thumbnail url in the place of this "larger" image and it worked. I was able to save the thumbnail offline, but I need to get the larger version (since, of course, the thumbnails are too pixelated).
I'm sure that the paths are ok since I got the thumnails working.
I'm lost. Is this not working because the file size is "larger"? Help please, Thanks!
The problem is NSFileHandle fileHandleForWritingAtPath can not create a file. You need to create the file first.
To save images to iPhone simply use
UIImageWriteToSavedPhotosAlbum(<#UIImage *image#>, <#id completionTarget#>, <#SEL completionSelector#>, <#void *contextInfo#>)
If you want to save images only 209*209 then add a check before that on the dimension of an image. I don't know(yet) how to read the images from iPhone, but you can use UIImagePickerController to choose the images.
Hope it helps
I'm writing a function to download a regular PNG file from web server and save it to iPhone Photos album. I don't get any error for my code listed below but UIImagePNGRepresentation doesn't perform the convert at all. All images I got were black. I have to enable "auto-enhanced" under Photos to display those image properly. Any clue what's wrong with my code? Thanks in advance.
UIImage *orgImg = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://server.com/test.png"]]];
NSData * convertedData = UIImagePNGRepresentation(orgImg);
UIImage * img = [UIImage imageWithData: convertedData];
// Save Image to Photo Album
UIImageWriteToSavedPhotosAlbum(img, self,
#selector(thisImage:hasBeenSavedInPhotoAlbumWithError:usingContextInfo:), nil);
Some more details of these two output images, orgImg and img:
If I pass orgImg to UIImageWriteToSavedPhotosAlbum directly, I did get the same PNG image hosted on the server. However Photos application on my iPhone displays it as a black image because Photos doesn't enhance PNG format automatically.
As for the img I got after using UIImagePNGRepresentation, the image data has been changed by the method, some meta data such as width/height have been removed from the original image. However Photos app on my iPhone still display it as an all black image.
Both images display properly if I copy them into either Safari or email. I didn't get any problem if I use JPEG in the server side either. Just curious why only PNG format doesn't work.
In my app i insert images in the tableview by putting the url of image in the field image of xml!!
It's possible insert the entire image directly in XML, including in the field image, instead of the URL, a kind of image compression, for example, the bits that make up the image.
This will increase the loading time a lot!
Search for a solution for "lazy loading" on the Web.
This is the most common approach for loading images in the table views on iPhone...
EDIT:
If you still want to use blub (image data as text inside the XML) then you might use the next code sample:
NSData *imageData = [NSData dataWithBase64EncodedString:imageString];
UIImage *image = [UIImage imageWithData:imageData];
I'm trying to take a screen shot of my app's current view and save it to photo album (to then be emailed or MMS'ed).
UIGraphicsBeginImageContext(self.view.bounds.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, self, #selector(savedPhotoImage:didFinishSavingWithError:contextInfo:), nil);
This works but the resulting image apears to be larger (533x800px) and heavily compressed when I email it from the photo library.
I've tried first writing the UIImage to file and then saving to album but still get the same issue.
If I used the in-built screenshot functionality on the iPhone the view saves correctly to photo album at 320x480 but the above code appears to save a larger image for some reason?
Thanks!
I found a decent workaround, which is to essentially rewrap the UIImage as a PNG, then save the rewrapped version. Code looks something like this:
UIImage* im = [UIImage imageWithCGImage:myCGRef]; // make image from CGRef
NSData* imdata = UIImagePNGRepresentation ( im ); // get PNG representation
UIImage* im2 = [UIImage imageWithData:imdata]; // wrap UIImage around PNG representation
UIImageWriteToSavedPhotosAlbum(im2, nil, nil, nil); // save to photo album
I had that same error, on my part, that was solved when I rounded the decimal points to be the same scale as the iPhone, try it, make sure the scale is 1.0, 2.0, etc and not 3.1, that will throw it off.