Preventing Overwrite When Calling writeToFile:

Question

I'm trying to save an image to the disk every time a save button is pressed. This is the code I'm using:

NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);

NSString* documentDirectory = [documentDirectories objectAtIndex:0];
NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:@"piclogs"];

[pdfData writeToFile:documentDirectoryFilename atomically:YES];

Now, obviously the file to be saved will overwrite the previously saved file every time this method is called. I'm trying to find a way to store every picture taken in there, rather than have it overwritten every time. Does anyone know if there is a simple solution to achieve this? I browsed through the docs but couldn't find anything relevant.

Answer 1

Use NSUUID or CFUUIDCreate to create a unique name that you can use for the file.

Answer 2

or you could check if the file with that name exists and if it does don't write to file. Then change the name if you want so you do have a copy of what you may or may not be trying to save.

NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);

NSString* documentDirectory = [documentDirectories objectAtIndex:0];
NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:@"piclogs"];
if (![NSURL fileURLWithPath:[self documentsPathForFileName:documentDirectoryFilename]]) {
    [pdfData writeToFile:documentDirectoryFilename atomically:YES];
} else {
    NSString* altName = [NSString stringWithFormat:@"%@-%d", documentDirectoryFilename, intValue];
    [pdfData writeToFile:altName atomically:YES];
}