Month: February 2019

Although modern iOS hardware is powerful enough to handle many intensive and complex tasks, the device could still feel unresponsive if you are not careful about how your app performs. In this article, we will look into five optimization tricks that will make your app feel more responsive.
1. Dequeue Reusable Cell

You’ve probably used tableView.dequeueReusableCell(withIdentifier:for:) inside tableView(_:cellForRowAt:) before. Ever wondered why you have to follow this awkward API, instead of just passing an array of cell in? Let’s go through the reasoning of this.

Say you have a table view with a thousand rows. Without using reusable cells, we would have to create a new cell for each row, like this:

As you might have thought, this will add a thousand cells to the device’s memory as you scroll to the bottom. Imagine what would happen if each cell contained a UIImageView and a lot of text: Loading them all at once could cause the app to run out of memory! Apart from that, every single cell would require new memory to be allocated during scrolling. If you scroll a table view quickly, a lot of small chunks of memory will be allocated on the fly, and this process will make the UI janky!

To resolve this, Apple has provided us with the dequeueReusableCell(withIdentifier:for:) method. Cell reuse works by placing the cell that is no longer visible on the screen into a queue, and when a new cell is about to be visible on the screen (say, the subsequent cell below as the user scrolls down), the table view will retrieve a cell from this queue and modify it in the cellForRowAt indexPath: method.
Cell reuse queue mechanism
How cell reuse queues work in iOS (Large preview)

By using a queue to store cells, the table view doesn’t need to create a thousand cells. Instead, it needs just enough cells to cover the area of the table view.

Imagine you design a system for data researchers. Or an application for energy management. Or a dashboard for corn traders. Maybe you’re designing something like that right now. In all the mentioned cases, people will expect tables. Not those fancy ones from design inspiration sites but Excel-looking monsters with hundreds of cells and complex interaction.

In this case, a designer faces many challenges. For instance, matching design with existing frontend frameworks or struggling with “uncomfortable” data that smashes the layout. We’ll overcome these problems by means of the following steps: systematize needs, go atomic, and define interaction.
A trendy-looking table with little data versus a busy complex table

Expectation vs. Reality

1. Systematize Needs

So, you’ve interviewed the target audience and figured out their needs and wants. Now it’s time to piece together findings and transform them into an interface structure. For example, one user said, “I need to see how my data affects other parts of the application.” Or while watching another person work with old software you noticed he uses shortcuts and doesn’t touch a mouse at all. What does it mean?

The first user’s words are about input validation and hints. You’ll need to consider attaching alert or help information to a table. Or develop a system of meaningful colors. It depends on the domain and the mental model. The observation of the second user’s work might be a sign you need to design all actions keyboard-accessible. And you’ll probably need to think about shortcuts more profound than just “Cmd + C” and “Cmd + V”.

There’s a good reason the majority of programming languages support regular expressions: they are extremely powerful tools for manipulating text. Text processing tasks that require dozens of lines of code can often be accomplished with a single line of regular expression code. While the built-in functions in most languages are usually sufficient to perform search and replace operations on strings, more complex operations — such as validating text inputs — often require the use of regular expressions.

Regular expressions have been part of the JavaScript language since the third edition of the ECMAScript standard, which was introduced in 1999. ECMAScript 2018 (or ES2018 for short) is the ninth edition of the standard and further improves the text processing capability of JavaScript by introducing four new features:

Lookbehind assertions
Named capture groups
s (dotAll) Flag
Unicode property escapes

As web developers, we are often required to create applications that are responsive as well as media-rich. Having such requirements in place means that we need to work with image breakpoints, as well as media queries since we want to provide the best experience to the end users. Adding to the list of requirements we may need to use a front-end framework such as Angular which is great for creating SPAs and other application types.

In this article, we’ll take a look at image breakpoints, their use-cases and throughout a hands-on example; we’ll implement them in an Angular application using Angular’s own BreakPoint Observer. While using this approach, we’ll also highlight why this popular framework helps us work with the aforementioned techniques in a seamless way.

In the era of responsive layouts (where we capture breakpoints based on the viewport size and based on the breakpoint we change the layout of the page), we also need to make sure that images can be displayed with the right dimensions — even after a layout change. Selecting the right image is quite challenging for modern responsive websites.