Swift Archives — Page 4 of 5 — Coding Explorer Blog

Hello World! Your first iOS App in Swift

Last updated on August 12, 2020

So far we’ve covered a lot of how Swift the language works, some WatchKit tutorials, and how to get started with some Cocoa classes. However, we have not really done much in the way of actually writing sample apps on the Coding Explorer Blog. It was covered a little bit in the WatchKit tutorials, but there is a lot done there specific to getting WatchKit working. Let’s go all the way back to the basics, let’s write a Hello World app.

For those that don’t know, it is very common to have the first program written by somebody learning a new language be one that somehow displays “Hello World!” At least according to Wikipedia, this goes back to an example from “The C Programming Language” book by Brian Kernighan and Dennis Ritchie. Now, of course the simplest form of this in Swift is just:

print("Hello, World!")

But we’ll do something a bit more advanced than that. You don’t often (or ever) see a console on your iOS device, so that doesn’t help us make an app directly.

This is a pretty basic tutorial, but I want to make it pretty comprehensive for how to start an iOS app. This will even include going over some of the features of the IDE (integrated Development Environment), like the different editors, the utility pane, and the various inspectors therein. This may be a bit too basic for some, but I want this site to be a place for all kinds of iOS developers, especially the beginners. We all had to start sometime, and those are the people I want to help in particular today.

Also, I figured that it’s a new year, let’s start it with how to start a new app.
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Swiftly getting a human-readable date with NSDateFormatter

Last updated on May 23, 2023

Now that we know a bit about Date and DateComponents, let’s actually get a readable date in our Swift app, shall we? This is the job of DateFormatter. DateFormatter is a class that can take a Date, and output a String describing that time/date as its format instructions dictate. In other words, you tell it what you want to know, and it will give you a String that says that. It has a few pretty useful built-in formats, and the capability to accept a custom date format string.

There’s not too much to the actual creation of an DateFormatter object. It pretty much just has an empty initializer (and an NSCoding one, but we aren’t covering NSCoding today). After initializing your DateFormatter, you set the appropriate style for the date and time, and that’s all you need.
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NSUserDefaults — A Swift Introduction

Last updated on August 12, 2020

So, let’s say we have an app that needs to remember a few simple things that the user puts in when they first load the app. It needs to remember the user’s name and birthday, to show on some view controller, or maybe even for a countdown on their Apple Watch.

There are plenty of ways to save data for your app. Some are easy to use, but rather limited, while others are much harder to use, but give you a lot more capabilities. Today, we are going to cover something on the easy, but limited end of the spectrum. For the app mentioned above, the information we’re storing will be used to set this app up with default values, for this user anyway.

That is why this method is called NSUserDefaults. It has its limitations, but it is very easy to use, and is ideal for simple storage of things like Strings and numbers.
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DateComponents — Class Reference

Last updated on August 12, 2020

As mentioned last time in my post Date — Class Reference, now we go a bit more in depth with DateComponents. In my opinion, this is the real powerhouse for dealing with time in Swift or Objective-C. When I was first learning iOS, I looked, understandably, at Date to work with dates. As such, a test project used Date and it’s initializers, including NSTimeInterval. When I had mentioned that at my local NSCoderNight, I was told to look into DateComponents, and boy was that good advice! Not only is it a pain to calculate the seconds for the intervals you want, what about dealing with Daylight Savings Time, leap years, or just plain different calendars! Now with DateComponents, I can set a date in a way that I understand, and in concert with Date and Calendar, it will even deal appropriately with the intricacies of calendars without me having to do so myself.

DateComponents can be used to either specify a specific date, or to specify a timespan in your Swift iOS apps. There is no difference between the uses as far as DateComponents is concerned you just set the appropriate components (year, day, hour, second, etc).
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Add sharing to your Swift app via UIActivityViewController

Last updated on August 12, 2020

In several iOS apps, such as Safari or the Camera app, you can click a button that brings up an interface that makes it easy to send or share what you are looking at via messages, Twitter, Facebook, etc. That interface is known as the UIActivityViewController. When I first learned about it, I didn’t even know what to search for. I think I originally started with “share sheet” and went on from there, so it may seem silly to point out something so obvious, but when I first tried, I knew what I wanted, I just had no idea what it was called.

If you’ve paid any attention to WWDC a few years, you have probably saw that this is the new home for Share and Action extensions. Today though, we are just going to cover the built in aspects of using UIActivityViewController in your Swift app. We will cover those sometime later.
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