Xcode, how do you take an app from an idea to a data model, data structure, or class structure?

Question

Hey everyone!
I'm a beginner xcoder and computer engineering sophomore and have literally spent every hour of the past few weeks reading as much as I possibly can about becoming a developer.
I've found plenty of documentation, and guides on how to do very specific things in xcode and objective-C but am still looking for more information on one topic; how do you decide which data models/structures/controllers etc to use?
I mean, you personally. I've been looking for a resource on this and have not been able to find one. I just finished Apple's iOS Developers Guide and they mention "choosing a data model" but do not describe them in much detail.
The following is what is provided in the guide:
● Choose a basic approach for your data model:
● Existing data model code—If you already have data model code written in a C-based language, you
can integrate that code directly into your iOS apps. Because iOS apps are written in Objective-C, they
work just fine with code written in other C-based languages. Of course, there is also benefit to writing
an Objective-C wrapper for any non Objective-C code.
● Custom objects data model—A custom object typically combines some simple data (strings, numbers,
dates, URLs, and so on) with the business logic needed to manage that data and ensure its consistency.
Custom objects can store a combination of scalar values and pointers to other objects. For example,
the Foundation framework defines classes for many simple data types and for storing collections of
other objects. These classes make it much easier to define your own custom objects.
● Structured data model—If your data is highly structured—that is, it lends itself to storage in a
database—use Core Data (or SQLite) to store the data. Core Data provides a simple object-oriented
model for managing your structured data. It also provides built-in support for some advanced features
like undo and iCloud. (SQLite files cannot be used in conjunction with iCloud.)
● Decide whether you need support for documents:
The job of a document is to manage your app’s in-memory data model objects and coordinate the storage
of that data in a corresponding file (or set of files) on disk. Documents normally connote files that the user
created but apps can use documents to manage non user facing files too. One big advantage of using
documents is that the UIDocument class makes interacting with iCloud and the local file system much
simpler. For apps that use Core Data to store their content, the UIManagedDocument class provides similar
support.
I suppose my question boils down to, how do you decide which structures to use? If you can provide an example of an app idea and how its implemented that would be very helpful and much appreciated!
For example, to implement the idea of an app which allows users to progress through levels of knowledge of a certain subject and rewarding them with badges and such (this is not an actual app just a whim) how would one model that?
Thanks in advance for all your help!!!

Answer 1

SgtChevelle wrote:
how do you decide which structures to use?
Trial and error.
I wish I had a better answer for you, but that pretty much encapsulates it. There is some, but not much, good wisdom out there, but it takes a significant amount of experience to be able to recognize it. The software development community if currently afflicted with a case of copy-and-paste-itis. And the prognosis is poor.
The solution is to be brutal to yourself and others. Focus on what you need and ignore everything else. Remember that other people have their own needs and methods and they might not be applicable to you. Apple, for example, can hire thousands of programmers, set them to coding for six months, pick the best results, and have the end-users spend their own time and monety to test it. If you don't have Apple's resources and power, think twice about adopting Apple's approach. And I am talking from a macro to a micro perspective. Apple's sample and boilerplate code is just junk. Don't assume you can't do better. You can.
Unfortunately, all this takes time and practice. You can read popular books, but never assume that anyone knows more than you do. Maybe they do and maybe they don't. It takes time to figure that out. Just do your best, ignore the naysayers, and doubt other people even more than you doubt yourself.