FriendFace 61 Feedback

As usual after a challenge, I compare my efforts to Paul’s model solution. Just to quickly recap the app, it sucks up some data (Users who have multiple friends) and displays it. The change in this challenge was to convert it to add that data to a Core Data store so that if a future network error prevented accessing new data, it could still display the old.

Merge Policy

The first difference is that Paul adds a merge policy. A Merge policy tells Core how to deal with any constraints defined in the data model. In this app, I’d defined the CachedUser.id as a constraint. The purpose of this is that under normal conditions the app would be picking up mostly the same data each time it started up. We don’t want scabs of duplicate data, so constraining users based on their unique id is smart.

Project 12 Feedback

As usual, I watch Paul’s solution video, and compare it to mine.

Task 1

This was passing in the predicate as a String. I passed the whole thing, but as I figured out along the way, Paul meant just the operator word. He also added some buttons to test it better, which I didn’t think of till Task 3 - it would have saved me some simulator runs.

Project 12 Challenges

Project 12 was a series of code tutorials around developing CoreData concepts rather than a real app, but the challenges are based on a very small app that uses a subview to allow dynamic (ie changeable at runtime) filtering of a list of data. The reason this would be tricky is that the @FetchRequest is a property of a view - and therefore mutable. The trick is to have a subview to build that part of the view, and to pass parameters into it which build the fetchrequest using an underscore.

Cupcake Corner Feedback

As usual, here’s my thoughts comparing my attempts at the challenges to Paul’s. Usually he’s better!

1) Whitespace

The task was to validate the order address properties, not just by checking they are not empty, but also that they don’t just contain spaces. I went the bruteforce route since there was no .isEmptyIncludingWhitespace method.

var hasValidAddress: Bool {
    let trimmedName = name.trimmingCharacters(in: .whitespacesAndNewlines)
    let trimmedStreetAddress = streetAddress.trimmingCharacters(in: .whitespacesAndNewlines)
    let trimmedCity = city.trimmingCharacters(in: .whitespacesAndNewlines)
    let trimmedZip = zip.trimmingCharacters(in: .whitespacesAndNewlines)

    if trimmedName.isEmpty || trimmedStreetAddress.isEmpty || trimmedCity.isEmpty || trimmedZip.isEmpty {
        return false
    }
    return true
}

As soon as Paul mentioned extending String, I facepalmed - of course, just create the method I want on string. Paul’s is a one line extension - neater, and Swiftyier.

Cupcake Corner challenges

Day 52 of #100Days was the challenges to the Cupcake Corner app - an app that allows you to build a one-row order, encode it as JSON and submit it to an API with a URLSession. To allow the order to be passed around, it’s an @ObservedObject which meant that a few extra hoops needed to be jumped through to make it Codable.

1) Whitespace validation

The tutorial app validates the order address by checking that each field is not empty, but it can be fooled by just entering some spaces. The first challenge was to fix that.