DevFright - Learn How to Create iOS Apps

How to Use the SwiftUI List View with Dynamic Cells

August 21, 2019 by Matthew Leave a Comment

In a recent tutorial we covered how to combine views and briefly touched on dynamic cells within a List. In this tutorial we’ll look more closely at how you can bring in dynamic content in to a List.

Create a new project and make sure you select SwiftUI when the option is presented.

Open up ContentView.swift and just below the import line at the top of the file, add the following struct:

struct Message: Identifiable {
    var id = UUID()
    var from: String
    var date: String
    var subject: String
    var snippet: String
}

struct Message: Identifiable {

var id = UUID()

var from: String

var date: String

var subject: String

var snippet: String

}

[Read more…]

Combining SwiftUI Views

August 20, 2019 by Matthew Leave a Comment

One of many things that make SwiftUI great is the ability to combine views. The template code when you create a new SwiftUI view contains the following:

struct ContentView: View {
    var body: some View {
        Text("Place Holder")
    }
}

struct ContentView: View {

var body: some View {

Text("Place Holder")

}

The body variable is expecting some View. In the example above we are returning a Text view which contains a string “Place Holder”. If you preview this in the canvas you will see the words “Place Holder”, without quotes, in the centre of the view.

Swift provides the ability to combine views so that more views can be combined in to one and then returned. In our Stacks tutorial we explain this. In short, you can combine views in to a HStack, VStack, or ZStack and return the stack as one view.

[Read more…]

How to Use the SwiftUI List View with Static Cells

August 19, 2019 by Matthew Leave a Comment

SwiftUI allows us to make static table views by using a List view. The SwiftUI syntax makes the process extremely simple. Unlike UITableViewControllers that require you to manually specify that you are using static cells, and then have to assign the table view controller a class, you simply just add “List { }” to your code and insert all of the views you want in-between the curly braces.

[Read more…]

SwiftUI HStack, VStack, ZStack Tutorial

August 16, 2019 by Matthew Leave a Comment

When you create a SwiftUI view, the protocol defines that we need to return “some View”. The word “some” means that we are dealing with an opaque result type. This is a new feature added added in Swift 5.1. An opaque result type means that we must return one, and only one, of the specified type, in this case something that conforms to the “View” protocol.

This highlights a problem. Imagine if our view, ie… the part that the user interacts with on screen, was only able to show one Text field or perhaps one button, then interfaces would be incredibly boring.

[Read more…]

Finding the Correct GTLRGmail_MessagePart

February 8, 2019 by Matthew Leave a Comment

With trying to get to grips with the Google APIs Client Library for Objective-C for REST I came across the need to search message parts to find the plain text and HTML content of each email. Although I haven’t settled on the final way to accomplish this, one way I am testing is using .filter on an array of GTLRGmail_MessagePart’s.

[Read more…]

Getting a List of Messages with the Gmail API

February 1, 2019 by Matthew Leave a Comment

After authenticating with Google using GoogleSignIn, one of the next steps I wanted to tackle in my app was retrieving a list of messages. Here is the reference on this part of the API. What we see is that it requires a userId (which is your email address… or alternatively just the value “me”).

It has some optional query parameters such as indicating if you want to also include trash and spam folders, as well as filtering on labels. You can also pass in a query string in exactly the same format as you would the Google Search Box on email. Such as “from:[email protected]”, or just by keyword or phrase, etc…

On the right of the page there is also a way to test this out. In userId put in your email address and in labelIds, put in the word INBOX in CAPS.

[Read more…]

Implementing GoogleSignIn with Swift

February 1, 2019 by Matthew Leave a Comment

I am currently in the process of building an email client app for iOS, and after that, the Mac. At the moment I am working on users being able to sign in to their Gmail account so that they can manage emails with within the app.

One of the first steps with working with the Gmail API is to be able to sign in. At the moment I have implemented GoogleSignIn which is one of a few ways that Google allows you to authenticate.

[Read more…]

How to Display HTML in UITextView with Swift

January 29, 2019 by Matthew Leave a Comment

I was working with the Google APIs Client Library for Objective-C for REST today and when working on retrieving email messages from Gmail I noticed that the Data being passed, once decoded from base64, contained HTML in some cases. In this quick tutorial I’ll provide a quick example of one way that you can display a string containing HTML and put it in a UITextView.

Instead of showing how to retrieve an email from Gmail, and then access the data string and go through the conversion to make it a readable string, I’ll just begin from a hard-coded HTML string and show how that can be used in a UITextView.

[Read more…]

Connecting to the DJI/Ryze Tello SDK with iOS and Swift – Tutorial

January 11, 2019 by Matthew Leave a Comment

I recently received a DJI/Ryze Tello as a gift from family. The Tello is a small drone weighing just 80g that works both indoors and outdoors (although you need good light and good conditions, ie, no wind, to be safe when using it outside). It has a downward facing vision system that allows it to stay steady when hovering. It works up to 100m away and is controlled by a smartphone or table via the Tello app.

The Tello has a 5mp camera on the front that streams 720p video to a phone or tablet. When you have a strong wifi signal, you can capture some fairly decent footage (not Spark, Air, or Mavic quality, mind you). There is no gimbal, although it does have electronic image stabilisation (EIS) which when the drone is in slow mode, it keeps the video level and fairly steady regardless of what direction you move the drone.

[Read more…]

Passing Data Between View Controllers with Swift

January 9, 2019 by Matthew Leave a Comment

When developing an app, you might come across a need to pass some data from one view controller to the next view controller.

To demonstrate this functionality, we will create a very simple contacts application. The main view will use a UITableView to show first and last names of each individual in the custom contacts list. When tapping a name, the app will segue to a second view to show the contacts phone number and other details.

There are many ways we can solve this problem, such as using notifications or delegates to pass information around, but in this example we will pass some information from one view controller to the next view controller so that the “next” view controller knows what information to store.

[Read more…]