FlickrAPi | Simple script interacting with Flickr 's public api | REST library

I'm following an example from an iOS programming book. The example in the book downloads photos from Flickr and place them in a collection view. Each photo are downloaded through a link as one of the elements of an object in a json code. The example uses Core Data for persistence of data and involves conversion from Core Data managed object type to custom object type.

The compiler reports that "Cannot convert value of type '[Photo]' to expected argument type '[FlickrPhoto]'". The [Photo] is an array of Photo objects which are automatically generated by Core Data according to Entity and Attributes information provided by me and the [FlickrPhoto] is an array of FlickrPhoto objects which are custom objects.

Please let me know what problem there is and suggest some solutions. Thank you!

Relevant code is as follows:

Photo+CoreDataClass.swift

I came across a json decoding error in an example in a book. The error says:

I have this app that searches tags on flickr and returns results.

The results are displayed on an infinite collection view.

Results are returned 100 at a time.

I start to scroll and reach the bottom of the scroll view. Another 100 elements are requested from Flickr and the thing works fine.

If I continue to scroll down for a while, after entering the 5th page (elements 400-499), I start to get this error:

I am trying to download some photos from Flickr. With My KEY and Secret, I am able to search and download using these lines of code

My goal is to extract geodata (lat and lon values), views, photo id's, url's and the date posted from the Flickr database inside the geographic boundaries of the city of Cologne, Germany. The data is then written in a csv file. The total number of results using just tags='Köln' is around 110.000. I want to extract at least a 5-digit number of data points from that. To achieve that, I set three delimiters: the tag, the maximum upload date and the minimum upload date.

What already works: The data is successfully written into the csv.

What does not work yet: When I return the search results using xml.etree.ElementTree.dump(), I can see that around 3,700 results are found for the respective search parameters. As far as I know, this number is inside the limit of 4,000 results per query set by Flickr. However, only between 700 and 1,000 data points are written into the csv file. The number is never the same and varies with every execution, which is weird, because I clearly defined the time frame. Also, despite adding a timer between calls using time.sleep(1) I still get kicked out by the server from time to time (error code 500). After struggling a lot with the barely documented limits, I really can't tell why my code is still not working as intended.

The code I used is as follows: