UIImage gets corrupted while Downloading - iphone

Question

I have developed iOS App, in which i am downloading image from server and saving it in my Document directory.
But problem which i am facing is, sometimes my images getting corrupted when i download, even if the server response isSuccessful.
Here is my code snippet,
urlFile is path of UIImage which is on server e.g: www.abcd.com/images/pqr.jpg
fileName which i am using for saving image name in my DocDirectory.
- (void)downloadFile:(NSString *)urlFile withName:(NSString *)fileName
{
NSString *trimmedString = [urlFile stringByTrimmingCharactersInSet:
[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(#"trimmedString=%#",trimmedString);
if ([trimmedString length]>0)
{
HTTPEaterResponse *response = [HTTPEater get:[NSString stringWithFormat:#"%#",trimmedString]];
if ([response isSuccessful])
{
NSLog(#"isSuccessful");
[self saveImage:[[UIImage alloc] initWithData:[response body]] withName:fileName];
} else {
NSLog(#"Url response failed %#", [response description]);
}
}
}
- (void)saveImage:(UIImage *)image withName:(NSString *)name
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSData *data = UIImagePNGRepresentation(image);
NSLog(#"image =%#",image);
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:name];
[fileManager createFileAtPath:fullPath contents:data attributes:nil];
}
When i see my Log, it shows:
trimmedString= www.abcd.com/images/pqr.jpg
isSuccessful
image =null
Thanks in advance.

Answer 1

I use the following code and it works for me.
NSData *thumbImageData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:ImageURL]];
[thumbImageData writeToFile:cachedThumbnailFileName atomically:YES];
UIImage * image = [UIImage imageWithContentsOfFile:cachedThumbnailFileName];
imageView.image = image;
Hope it helps you. :)

Answer 2

To save image on directory use:
NSString *pngPath = [NSHomeDirectory() stringByAppendingPathComponent:#"Documents/Test.jpg"];
[UIImagePNGRepresentation(selectedImage) writeToFile:pngPath atomically:YES];
NSError *error;
NSFileManager *fileMgr = [NSFileManager defaultManager];
NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:#"Documents"];

Answer 3

have you logged the response [response body]?
Just try to convert that response as NSData and then save as image.
Using Base64Encoding class,you can convert the response as base64Data
NSData *imageData = [NSString base64DataFromString:[response body]];
[self saveImage:[[UIImage alloc] initWithData:imageData] withName:fileName];

Answer 4

i suggest yo use SDWebimage Class SDWebimage download.. i think its very helpful to you even i always prefer SDWebimage Library.
this are the some things.
An UIImageView category adding web image and cache management to the Cocoa Touch framework
An asynchronous image downloader
An asynchronous memory + disk image caching with automatic cache expiration handling
Animated GIF support
WebP format support
A background image decompression
A guarantee that the same URL won't be downloaded several times
A guarantee that bogus URLs won't be retried again and again
A guarantee that main thread will never be blocked
Performances!
Use GCD and ARC

Answer 5

instead u can use, "NSURLRequest" and "NSURLConnection"
for example if u get image URL then,
NSURL* aURL = [NSURL URLWithString:trimmedString];//get the url of string
NSURLRequest *aReq = [NSURLRequest requestWithURL:aURL];
NSURLConnection *aConnection = [NSURLConnection connectionWithRequest:aReq delegate:self]; //get a connection to url , since it confirms to delegate u need to implement delegate methods
if(aConnection == nil) //if it is nil then cancel and close the request
{
aConnection = nil;
[aConnection cancel];
}
// after this implement this delegate methods
- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)received_data
{
if(image_data == nil) //if data is not initialised initialise it
{
image_data = [[NSMutableData alloc]init];
}
[self.image_data appendData:received_data];//append the received data
}
//this method is called after successful download of the image
- (void)connectionDidFinishLoading:(NSURLConnection *)connection;
{
// UIImage* sampleImage = [UIImage imageWithData:self.image_data];
// self.image = sampleImage; //convert the data to image
//since u hav complete downloaded date in "self.image_data"
NSString *imagePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:#"/myImage.png"];//set the name of the image and path may it saving in application directory check it out
[self.image_data writeToFile:imagePath atomically:YES]; //saving the data with name
}
Hope this helps u :)