Write UIImage to documents directory

writeUIImageToDocs.mm

// UIImage called 'image'

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:@"foo.png"];
NSData *imageData = UIImagePNGRepresentation(image);
[imageData writeToURL:[NSURL fileURLWithPath:filePath] atomically:YES];
NSLog(@"written to %@", filePath);