Adding MobileIron AppConnect to a Swift application

If you work on an iOS application intended for corporate environments, you are probably familiar with MobileIron AppConnect, because it is the most commonly used MDM solution. They have an SDK for iOS with stated support for Objective-C, Xamarin C# bindings and an Cordova plugin. If your application is written completely in Swift, there is some bad news in the documentation:

NOTE: The AppConnect for iOS API supports apps written in Objective-C. It does not support apps written in Swift.

Luckily, this is not true, you can integrate the AppConnect SDK to an application written entirely in Swift, you just need to do a few more steps.

First, add the SDK to the project exactly as the documentation says:

  • Add AppConnect.framework to your Xcode project
  • Add the libcrypto.a library
  • Add the libProtocolBuffers.a library
  • Link the Security framework
  • Link the Mobile Core Services framework
  • Link the Local Authentication framework
  • Add linker flags
  • Copy bundle resources from AppConnect.framework
  • Register as a handler of the AppConnect URL scheme
  • Declare the AppConnect URL scheme as allowed

When you encounter the Use AppConnect’s UIApplication subclass step you have a problem, you cannot do it in a Swift application the same way as in Objective-C. You need to use the Info.plist in your project and add a key called NSPrincipalClass with the value of AppConnectUIApplication instead. This ensures your main application class inherits from the required AppConnect class.

<key>NSPrincipalClass</key>
<string>AppConnectUIApplication</string>

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Writing a simple Pascal interpreter in Swift

About a month ago I stumbled on a series of blog post called Let’s build a simple interpreter by Ruslan Spivak. In these blog posts the author write about building a simple interpreter for the Pascal programming language in Python. It is very well written and explained, I would even say that all the concepts are explained better than in the compiler course I took at the university.

In that class I had to write a Pascal compiler not interpreter in C++ and with tools like lex and yacc so I remembered most concepts but the interpreter is a bit different than a compiler and not using any external tools makes you think more about the problem.

Motivation

I felt a bit nostalgic and wanted to tackle an algorithmically challenging problem, especially because Pascal was my first programming language back in high school so I decided to follow along and write a simple Pascal interpreter in Swift, the language I switched to from C# nearly a year ago.

Swift is a different language than Python so I had to do many things differently, especially those where the Python implementation relayed on the dynamicity of the language.

But the biggest challenge was that the series ended before introducing function calling and the call stack so I had to come with a good way to do this. I also wanted to support recursion and basic loops and flow controls.

Goal

The goal was to be able to interpret a Pascal program like factorial computation or a simple number guessing game.

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swift  ios 

Workaround for receive remote notification callback not getting called in foreground on iOS 11

When your iOS application receives a push notification while in foreground, the didReceiveRemoteNotification method in the application’s AppDelegate gets called. You get the whole push notification payload and you can react to it. But there is a problem introduced in iOS 11, then fixed and then broken again (like many things done by Apple these days) that didReceiveRemoteNotification does not get called when a push notification arrives and the application is in foreground. This can be really bad if your application depends on reliable push notifications while running.

The worst thing about this problem is that everything seems to be working while you are debugging the application from XCode. The method gets called, the payload is available. But when you open the application in your iPhone or iPad without the debugger attached, didReceiveRemoteNotification just never gets called. There are many developers reporting this problem on the Apple forums and on StackOverflow.

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ios  swift 

My experience with Swift after 9 months

About 9 months ago I basically left the world of Windows development because of the death of Windows Phone and me being really fed up with Microsoft. I got a chance to work on a complete native rewrite of an iOS application so I turned my desktop PC into a hackintosh and started learning Swift and iOS development.

This post describes my experience and feelings about Swift, the language, tooling, resources after 9 months. I will probably write another post about my experience with iOS development and the iOS community.

Swift language

I think Swift is a nice modern language, it reminds me of a combination of C# and F#, so two languages I really like. The introduction of Swift got me first thinking about switching to iOS development, Windows Phone was already dying at that time.

I tried iOS development with Objective-C some time ago, did some tutorials but the language just felt wrong. Not only the strange syntax, I do not really care about that, but the expressiveness of the language compared to C#. I had to write so much more code to do anything. Swift is just much better with that.

As a side note I remember reading Masterminds of Programming a few years back, the interview with one of Objective-C authors and his hate about C++ saying he did everything better that Stroustrup and thinking “I really do not like this guy” (I do not remember if it was Cox or Love).

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swift  ios 

Filling UITableView with data from bottom to top

If you work on something like an chat app, you may need to use the UITableView in a way where data is filled from bottom to top. An example of this is a chat detail screen, where you want the UITableView to show the latest messages at the bottom when loaded, new messages are added to the bottom and immediately shown and older messages are loaded on top when the user scrolls to the top of the UITableView.

There are multiple ways to achieve this, each with some advantages and disadvantages.

Scrolling

The first simplest idea that comes to mind is using the UITableView as is and just scrolling it when necessary:

  • Scroll to bottom when the initial messages are loaded
  • Scroll to bottom when a new message is added
  • When older messages are about to be added to the top, remember the position, add the older messages, scroll back to that position

The first two situations are easy to accomplish, but the last one is not. I could not find a way to make it works without a visible scrolling effect.

Rotating UITableView 180 degrees

Another solution is to rotate the UITableView by 180 degrees; rotating it upside down. Of course you have to also “flip” your data source but that is trivial to achieve. The advantage is that you do not have to do any scrolling when new messages are added to the bottom (which is the top of the rotated UITableView) and if you use batch updates instead of reload neither when older messages are loaded.

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ios  swift 

More readable XCode build output for CI

If you use Continuous Integration (CI) builds or build your app from the command line using xcodebuild you know that the output is not pretty and not very readable. Reading the build output is important when a CI build breaks, but it is not easy when it looks like this

Many iOS developers were not satisfied with this so the xcpretty project was created. Xcpretty is a fast and flexible formatter that turn the output from screnshot above to this neatly formatted output

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ios  macos  xcode 

iOS tip: Wireless debugging from XCode

One of the best XCode 9 features is the ability to deploy and debug iOS app on your device over WiFi, with no need to have the device connected to you computer by a cable. The only requirement is that the device runs iOS 11.

Setting it up is really easy. Connect the device using a cable like you normally do and go to Window | Devices and Simulators. You will see a new checkbox next to your iOS 11 devices called Connect via Network (see screenshot below), so check it. Now you can disconnect the cable and debug on your device over WiFi, the device has to be on the same network as your computer of course.

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ios  macos  xcode 

Fixing black artifact when changing large titles mode in iOS11

One of the new features of iOS 11 is the ability to display large headers in the navigation bar by setting the prefersLargeTitles property to true. You can set it for the whole app (using the UIAppearance for example) or differently for each view controller.

But there is a problem. If you navigate from a view controller with large titles enabled to a view controller with large titles disabled, you will see a black artifact under the change animation:

The black artifact comes from the navigation controller. If you set the backgroundColor of the navigation controller’s view to any, like red, it will replace the black artifact with an artifact of that color. The solution is to set the color of the color of you UI, white in my case:

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ios  swift 

Creating a dropdown menu from iOS navigation bar

Working on an iOS app I had to implement a filter for the table view displayed on screen. The filter should have contained 5 items and be accessible when tapping the screen title in the navigation bar. My first idea was to use an UIAlertController with those 5 options. It worked but it looked really ugly, So I started searching for a better, nicer solution. Ideally some kind of a dropdown menu.

I found multiple libraries for an iOS dropdown menu, but I liked BTNavigationDropdownMenu the best. The usage is really simple. First you define the items for the dropdown as an string array

let items = filterOptions.map({ $0.description })

create the menu instance

let menuView = BTNavigationDropdownMenu(navigationController: self.navigationController, containerView: self.navigationController!.view, title: BTTitle.title("Dropdown Menu"), items: items)

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ios  swift 

iOS tip: Changing navigation bar vs tab bar title

The UI of the iOS app I currently work on contains a tab bar with “Profile” as the title of one of the included tabs. This “Profile” tab contains a view controller with a navigation bar where I wanted the title to be set as “You profile”.

So I set the tab bar item’s title to “Profile” and wanted to set the navigation bar title of the view controller the standard way

title = "Your profile"

I noticed that this also changes the title in the tab bar. After some research I found out that changing the view controller’s title property changes bot the title in the navigation bar and in the bar bar. But you can change the title just for the navigation bar

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ios  swift