How to store a NSData locally - ios

Question

I am getting various format of documents with extension as .png,.txt,.jpg,,mp3 etc as NSData formatt, I need to store these locally and view it ,I have tried this
NSData* conData = [convStr dataUsingEncoding:NSUTF8StringEncoding];
NSLog(#"the converted string to nsdata is :%#",conData);
[conData writeToFile:#"Filename.txt" atomically:YES];
but unfortunately this is not working can any one help.

Answer 1

Note - writing NSData into a file is an IO operation which may block your main thread use dispatch, also provide file path for writing instead file name only.
This writes file for me
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
// Generate the file path
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:#"Filename.txt"];
// Save it into file system
[data writeToFile:dataPath atomically:YES];
});

Answer 2

you should pass a correct path in writeToFile method
NSString *docsDir;
NSArray *dirPaths;
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
NSString *targetPatch = [[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent:#"Filename.text"]];
[data writeToFile:targetPatch atomically:YES];

Answer 3

You have given only file name(Filename.txt) not whole file path thats why your code is not working.
Check below line of code you will get idea.
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:#"%#/%#", documentsDirectory,#"Filename.txt"];
[urlData writeToFile:filePath atomically:YES];