iPhone Load and Save Multiple UIImages with Unique Key? - iphone

Question

I know there are some solutions out there for saving and loading images on your iPhone. However none have quite worked for me.
For example, the link below has a great code chunk which lets you load and save a UIImage with a unique key, but I can't work out how to tell when loading an image using this code if an image under that key already exists or not.
http://www.friendlydeveloper.com/2010/02/using-nsfilemanager-to-save-an-image-to-or-loadremove-an-image-from-documents-directory-coding/
//saving an image
- (void)saveImage:(UIImage*)image:(NSString*)imageName {
NSData *imageData = UIImagePNGRepresentation(image); //convert image into .png format.
NSFileManager *fileManager = [NSFileManager defaultManager];//create instance of NSFileManager
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //create an array and store result of our search for the documents directory in it
NSString *documentsDirectory = [paths objectAtIndex:0]; //create NSString object, that holds our exact path to the documents directory
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.png", imageName]]; //add our image to the path
[fileManager createFileAtPath:fullPath contents:imageData attributes:nil]; //finally save the path (image)
NSLog(#"image saved");
}
//removing an image
- (void)removeImage:(NSString*)fileName {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.png", fileName]];
[fileManager removeItemAtPath: fullPath error:NULL];
NSLog(#"image removed");
}
//loading an image
- (UIImage*)loadImage:(NSString*)imageName {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.png", imageName]];
return [UIImage imageWithContentsOfFile:fullPath];
}
If you could help me work out that out it would be really appreciated. I need to save several images, and load them depending on if a given key already exists or not.

Answer 1

if u want to get images with unique key, try using UUID. This will always give u image with unique key..For example here is an example of using UUID..
- (NSString *)pathForImageFileWithPrefix:(NSString *)Prefix
{
CFUUIDRef uuid;
CFStringRef uuidStr;
uuid = CFUUIDCreate(NULL);
uuidStr = CFUUIDCreateString(NULL, uuid);
NSData *imageData = UIImageJPEGRepresentation(chosenImage, 1.0);
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
result = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#_%#.png",Prefix, uuidStr]];
[imageData writeToFile:result atomically:NO];
CFRelease(uuidStr);
CFRelease(uuid);
return result;
}

Answer 2

If I get your question right, you want to know whether a file with the given image name already exists? Then you can just use
bool fileExists = [NSFileManager defaultManager] fileExistsAtPath:filePath];