Firebase Storage retrieval images - swift

Question

I'm trying to get my head around Firebase Storage.
I've seen online and tried two methods of getting my images.
What is the difference between these two? (both work).
So after I get the photoUrl from my Firebase Database:
1.
if let data = NSData(contentsOfURL: NSURL(string:photoUrl)!)
{
let myImage = UIImage(data: data)!
MyImageCache.sharedCache.setObject(myImage, forKey: self.key)
//etc
}
2.
self.storage.referenceForURL(photoUrl).dataWithMaxSize(1 * 1024 * 1024) { (data, error) -> Void in
if (error != nil)
{
print(error)
}
else
{
let myImage = UIImage(data: data!)
MyImageCache.sharedCache.setObject(myImage!, forKey: self.key)
//etc
}
}

Answer 1

Regarding the first method, you shouldn't be using that for network calls. From the docs:
Do not use this synchronous method to request network-based URLs. For network-based URLs, this method can block the current thread for tens of seconds on a slow network, resulting in a poor user experience, and in iOS, may cause your app to be terminated. Instead, for non-file URLs, consider using the dataTaskWithURL:completionHandler: method of the NSURLSession class. See URL Session Programming Guide for details.
The second method is baked into the firebase framework and provides you with convenience methods for downloading an image, i.e. it gives you the option to specify images size. This is probably optimised for getting images and is in most scenarios the preferred method.