Managing user input

When dealing with user input, Murphy’s Law will always apply in full force: “Anything than can go wrong will go wrong”. Or as Douglas Adams would have it:

“A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools”

This is a common crux for us developers: how do we architect a completely foolproof system? There are many routes you can take to do this, but in this particular blog post, I would like to focus on a specific aspect of this: managing user inputs.

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Hashing

I find it hard to believe that any developer can deny the importance and usefulness that a right use of hashes can offer their applications.

From security and data management to object comparisons, hashes are used extensively throughout the framework and should, in the right circumstances, be used by you as a developer when the time merits them. But, what exactly is a hash? Simply speaking it’s a form of encryption that maps data of arbitrary length to a data object of a fixed size (number, string, etc),  but if you want to get all technical you can read this article on Wikipedia, wherein it explains hashes and it’s use through hash functions:

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Automating keyboard layouts

Normally, developing a keyboard interface starts with putting a UITextField, a UITextField, or another UIResponder into your application’s view hierarchy…

And then this component becomes a statement: “From here forth, I declare this view to be a keyboard input view”. Except… Well… it isn’t, or at least doesn’t act like it. Unless you manage the layout of your content by implementing your keyboard notifications, the app’s main view will not respond or adapt to the keyboard update, and all sort of messed up situations can arise from this, like the keyboard overlaying your UITextField, UIScrollViews not being able to scroll or UITableViews not being able to display their last rows of content.

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Subscripting String Shortcuts

The use of subscripts in Swift has added a few nice features to its predecessor in Obj-C, not only for reading, but also for writing your own implementations.

If you are not familiar with subscripts, they define the logic that allows you to write shortcut accessors and setters for objects that can be understood as a collection, and are most commonly used in Arrays and Dictionaries:


var array = ["Hello", " ", "World", "!"]
array[2] //subscript returns "World"
array[2] = "Everybody" //The word "World" is now replaced with "Everybody" using a subscript

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Smarter Numbers. Annex 1: Custom operators.

On my earlier post, “Smarter Numbers”, we talked about using operator overrides in swift to extend the functionality of framework classes.

There’s a bit more to it than what was discussed in the article, but we’ve decided to keep it as a separate post due it’s less “orthodox” usage: Swift also allows you to, in what could be considered as a controversial feature, create custom operators. This means that not only can you change the behaviour of the language. you can also change the language itself*.

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Smarter Numbers

When it comes to iOS app Development, I find one of the most commonly used framework class is NSNumber.

Which is ironic, because it’s a pretty dumb class. Really… there’s not much you can do with it except store numbers and check for equality. Albeit it being all over the place, it’s a pretty useless wrapper object. Whenever we need to edit the wrapped value we need to go through overly complicated statements like this:


number1 = NSNumber(float: number1.floatValue + number2.floatValue)

Fortunately for us, Swift is AWESOME.

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Ready… Set… Xcode! Annex 1: General project architecture… Explained.

A more detailed explanation for the architecture diagram referred to in “Ready… Set… Xcode!”.

On my first blog post, “Ready… Set… Xcode!“, we spoke about a general project architecture that is common to standard iOS Apps (note that architecture for games can be considerably more complex).

Here is a copy of the diagram to refresh our memory:Untitled drawing As you can see, in the middle we have the one design pattern to rule them all: the MVC pattern, roughly taking around 70% of the entire application’s architecture. A brief explanation of the components in this diagram follows: BASE (what you get for free):

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Ready… Set… Xcode!

As is common in every app development cycle, there comes a time when we must start setting up a project.

This normally involves mundane and boilerplate tasks such as setting up folder structures, linking up the project to the right third party libraries (if needed) and adding reusable extensions/categories/classes from earlier projects that we have grown an affection towards or have become fully dependant on. Depending on your ability, how meticulous and orderly you are with these kind of things, your team size, the project size and how important an understanding of the overall architecture is for you as developer (very important), this can take you anywhere from a couple of hours to (hopefully not more than) a day. Depending on how many applications you work on during the course of your career, these times add up to considerable numbers (make the maths in your head and cringe).

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