(We don’t want to have NSDateFormatter code, for example, inside the View.) storyboard files, which should only display prepared data.
View is represented by the UIView or UIViewController objects, accompanied with their. In the MVVM design pattern, Model is the same as in MVC pattern. Since UIViewController is supposed to be a Controller in the MVC pattern, and it’s already doing a lot with the Views, we can merge them into the View of our new pattern - MVVM. This is where the MVVM pattern comes in handy.
#Swift note taking app solution viewcontroller code#
Instead you should’ve wrapped that code inside of a custom UIView subclass.Įasy to see that this could lead to View and Controller code paths getting crossed. This mixture of view and controller code often happens when you move IBOutlets of little subviews inside the UIViewController, and manipulate on those subviews directly from the UIViewController. Notice that in its name, it contains both the “view” and the “controller.” This means that it “controls the view.” It doesn’t mean that both “controller” and “view” code should go inside. View is also responsible for notifying the Controller about any actions, such as user touches.Īs mentioned, UIViewController is usually the starting point in building a UI screen. In the MVC design pattern, View is supposed to be inactive and only displays prepared data on demand.Ĭontroller should work on the Model data to prepare it for the Views, which then display that data. Related: The 10 Most Common Mistakes iOS Developers Don't Know They're Making Upgrading to the MVC Design Pattern Even Apple uses UIViewControllers in its main system app when it switches between different apps and its animated UIs.Īpple bases its UI abstraction inside the UIViewController, since it is at the core of the iOS UI code and part of the MVC design pattern. It represents the physical screen you’re seeing while using any app with your iOS device. The UIViewController is the logical place to start working on your UI code. Then data formats started to change, UI evolved and needed some radical changes, and you just kept adding more ifs into an already massive if-ology.īut, how come the UIViewController is what got out of hand? The ViewController kept growing when the user authorization code came along. Or, even worse, you did that inside the same method. json, so you wrote yet another temp method to accomplish that. Next, you needed to process the data inside that. You were in a rush to see how the back-end data was behaving inside the UITableView, so you put a few lines of networking code inside a temp method of the ViewController just to fetch that. The likely reason is something like this: Your ViewController code has become the infamous spaghetti code. All that code imprisoned inside if-ology of a single file that cannot be reused and would only fit in this project. Networking code, data parsing code, data adjustments code for the UI presentation, app state notifications, UI state changes. In no time, your starting ViewController has become too smart and too massive. There comes the Model-View-ViewModel (MVVM) design pattern that saves the day. However, this pattern has its own issues. The first step to resolve this is to apply the Model-View-Controller (MVC) design pattern. You ended up with a lot of spaghetti code. Suddenly, you have more than 3,000 lines of code. However, it’s time to do something with all these UI elements UIButtons will receive finger touches, UILabels and UITableViews will need someone to tell them what to display and in what format. IBOutlets and IBActions are also included. UITextField here, UITableView there, a few more UILabels and a pinch of UIButtons. You start transferring UI screens from the designer’s sketches into your ViewController. sketch documents, and you already have a vision about how you’ll build this new app. So you’re starting a new iOS project, you received from the designer all the needed.