Images downloading intermittently - ios

Question

I have an iPad app which connects to a C# web service to download documents and images.
If I run it as a fresh install on the iPad, it downloads the expected documents and images. If I upload a new document and relaunch the app, it downloads it as expected. However, if I upload a new image to the server and run it again, it doesn't download the new image.
Here is the code for checking and downloading documents:
- (void)checkFiles:(NSString *)sessionID
{
fileList = [[NSMutableString alloc] init];
// get contents of doc directory
NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [directoryPaths objectAtIndex:0];
NSString *downloadsFolderString = [documentsDirectory stringByAppendingPathComponent:DOWNLOADS_FOLDER];
NSError *error = nil;
NSString* file;
NSDirectoryEnumerator* enumerator = [[NSFileManager defaultManager] enumeratorAtPath:downloadsFolderString];
while (file = [enumerator nextObject])
{
BOOL isDirectory = NO;
[[NSFileManager defaultManager] fileExistsAtPath: [NSString stringWithFormat:#"%#/%#", downloadsFolderString,file]
isDirectory: &isDirectory];
if ([file rangeOfString:#"LinkIcons"].location == NSNotFound)
{
if (!isDirectory)
{
[fileList appendString:[NSString stringWithFormat:#"%#|", file]];
}
}
}
// create string to send to server
NSString *post = [NSString stringWithFormat:#"sessionID=%#&fileList=%#&dateTime=%#&userID=%#", sessionID, fileList, timeOpened, userID];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%d", [postData length]];
NSString *comparisonURLString = SERVER_COMPARE_URL_STRING;
NSURL *comparisonURL = [NSURL URLWithString:comparisonURLString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:comparisonURL];
[request setHTTPMethod:#"POST"];
[request addValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:postData];
// get response - list of files for download
NSHTTPURLResponse *urlResponse = nil;
error = nil;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];
if (responseData)
{
NSString *requiredFilesList = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
// remove xml nodes from list
NSArray *lines = [requiredFilesList componentsSeparatedByString: #"\n"];
if (lines.count > 2)
{
// create sub array without xml nodes
NSRange theRange;
theRange.location = 2;
theRange.length = [lines count] -3;
numberOfFilesToBeDownloaded = theRange.length;
if (numberOfFilesToBeDownloaded <= 0)
{
_jobStatusLabel.text = #"Documents up to date";
}
if (numberOfFilesToBeDownloaded > 0)
{
NSArray *subArray = [lines subarrayWithRange:theRange];
[self getFiles:subArray];
}
}
}
[self checkLinks];
}
and:
- (void)getFiles:(NSArray *)filenames
{
downloadManager = [[DownloadManager alloc] init];
downloadManager.delegate = self;
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *downloadFolder = [documentsPath stringByAppendingPathComponent:#"downloads"];
for (NSString *filename in filenames)
{
NSString *downloadFilename = [downloadFolder stringByAppendingPathComponent:filename];
NSString *baseUrlString = SERVER_DOWNLOAD_URL_STRING;
NSString *finalUrlString = [baseUrlString stringByAppendingPathComponent:[filename stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[downloadManager addDownload:downloadFilename fromUrl:[NSURL URLWithString:finalUrlString] ];
[self notifyServerFileDownloaded:filename];
}
}
And this is the corresponding code for the images:
- (void) checkLinks
{
NSMutableString *linkListOnDevice = [[NSMutableString alloc] init];
NSMutableArray *globalLinksArray = [[[NSUserDefaults standardUserDefaults] objectForKey:#"globalLinksArray"]mutableCopy];
if(globalLinksArray != nil)
{
NSLog(#"Links Array found. Contents: %#", globalLinksArray);
}
else
{
globalLinksArray = [[NSMutableArray alloc] initWithCapacity:0];
}
NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [directoryPaths objectAtIndex:0];
NSString *downloadsFolderString = [documentsDirectory stringByAppendingPathComponent:DOWNLOADS_FOLDER];
NSString *LinksFolderString = [downloadsFolderString stringByAppendingPathComponent:#"/LinkIcons"];
NSError *error = nil;
NSString* file;
NSDirectoryEnumerator* enumerator = [[NSFileManager defaultManager] enumeratorAtPath:LinksFolderString];
while (file = [enumerator nextObject])
{
BOOL isDirectory = NO;
[[NSFileManager defaultManager] fileExistsAtPath: [NSString stringWithFormat:#"%#/%#",downloadsFolderString,file]
isDirectory: &isDirectory];
if (!isDirectory)
{
[linkListOnDevice appendString:[NSString stringWithFormat:#"%#|", file]];
}
}
// create string to send to server
NSString *post = [NSString stringWithFormat:#"iconsList=%#&userID=%#", linkListOnDevice, userID];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%d", [postData length]];
NSString *comparisonURLString = SERVER_COMPARE_LINK_ICONS_URL_STRING;
NSURL *comparisonURL = [NSURL URLWithString:comparisonURLString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:comparisonURL];
[request setHTTPMethod:#"POST"];
[request addValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:postData];
// get response - list of files for download
NSHTTPURLResponse *urlResponse = nil;
error = nil;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];
NSString *requiredIconsList = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
// remove xml nodes from list
NSArray *lines = [requiredIconsList componentsSeparatedByString: #"\n"];
// create sub array without xml nodes
NSRange theRange;
theRange.location = 2;
theRange.length = [lines count] -3;
numberOfFilesToBeDownloaded += theRange.length;
NSArray *linkSubArray = [lines subarrayWithRange:theRange];
NSMutableArray *iconsArray = [[NSMutableArray alloc] initWithCapacity:0];
NSString *linkDetail;
for (linkDetail in linkSubArray) {
[globalLinksArray addObject:linkDetail];
}
[[NSUserDefaults standardUserDefaults] setObject:globalLinksArray forKey:#"globalLinksArray"];
[[NSUserDefaults standardUserDefaults] synchronize];
// separate file for download from rest of string
for (NSString *linkString in linkSubArray)
{
NSArray *spltArray = [linkString componentsSeparatedByString:#"^"];
NSString *linkIconString = spltArray[3];
[iconsArray addObject:linkIconString];
}
[self getLinks:iconsArray];
}
and:
- (void) getLinks: (NSMutableArray *) linkList
{
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *downloadFolder = [documentsPath stringByAppendingPathComponent:#"downloads"];
for (NSString *filename in linkList)
{
NSString *downloadFilename = [downloadFolder stringByAppendingPathComponent:filename];
NSString *baseUrlString = SERVER_DOWNLOAD_URL_STRING;
NSString *finalUrlString = [baseUrlString stringByAppendingPathComponent:[filename stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[downloadManager addDownload:downloadFilename fromUrl:[NSURL URLWithString:finalUrlString] ];
}
}
Can anyone shed any light on why this works for documents but for images only on first run but not subsequently?

Answer 1

1) write this on didFinishLaunchingWithOptions method
NSString *savedValue = [[NSUserDefaults standardUserDefaults]
stringForKey:#"FirstTime"];
if (![savedValue isEqualToString:#"1"])
{
//Call for download image OR image downloading coding.
}
2) When image downloading complete then store value in NSUserDefaults
NSString *valueToSave = #"1";
[[NSUserDefaults standardUserDefaults]
setObject:valueToSave forKey:#"FirstTime"];
3) when next time your app is run then (1) condition is true and it not download image next time. If you want to download this then delete your app from simulator or device and clean then run the app.