DevFright

Learning Programming

Touch ID Tutorial – Objective-C

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The 5S was the first iPhone that integrated a fingerprint sensor in to the home button. When configuration is complete, it allows quick access to the iPhone by checking if your fingerprint matches one that is stored. If there’s a match, you get in and if not, it denies access.

When Touch ID was introduced in iOS 7 on the iPhone 5S, it was only available for Apple apps. When iOS 8 launched, they allowed 3rd party developers to also access this feature. In todays tutorial, we’ll take a look at how to integrate touch ID in to your iPhone app. Note that since the new iPad air and new iPad mini now include a touch ID sensor, this tutorial is also compatible with those devices although I will be testing with an iPhone 6.

Requirements

This tutorial requires that you have an iPhone 5S or newer or the latest iPad air or latest iPad mini (basically any iOS device with a touch ID sensor). You also need to be running iOS 8 or newer and also be using Xcode 6. Because we will be testing on an actual device rather than a simulator, you will also need to be enrolled in the iOS developer program and have paid the $99 yearly fee.

Creating the Project

First, load up Xcode 6 and go to create a new project. To save some steps setting up a default view, select the Single View Application (in the iOS section) and click Next. Give the project a name such as Touch ID and fill in the Organisation name, Organisation Identifier and set the other options as below. Note that the general way we select an organization identifier is by spelling out a name in reverse. In the case of our app development business which is mobient.co.uk, we reverse that by putting uk.co.mobient. In the Bundle Identifier line below, the Touch-ID (project name with hyphen automatically added) gets appended to the end.

New_Project [Read more…]

iOS Data Download Progress Bar Tutorial

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You have probably seen a number of times an app that shows the progress of a download. Today, we’ll look at one way how this is accomplished. In this tutorial I’ll show you how to create a progress bar that fills up as more data is downloaded. The data we’ll download will be an image downloaded from the internet.

iOS Progress Bar Tutorial

Lets begin by loading up Xcode and creating a Single View Application.

Call the project “Progress Bar” and leave the rest of the options as default. You can choose iPad or iPhone for this project although we’ll create it for the iPhone in this tutorial. When you get to the option on the next page asking if you want a GIT repository, you can either select or deselect it.

navigationWhen the project is ready to go, load up the storyboard by clicking on Main.storyboard in the navigation pane to the left. When the storyboard loads up, you will see just a single view that is currently empty. We need to add a few objects to it which will include a progress bar and an image view. All this simple app will do is load up a pre-defined URL and as the page loads, it will show the progress of the page load and when done, it will show the item on screen. [Read more…]

NSArray sortedArrayUsingComparator Tutorial

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Occasionally you will come across the need to re-order the contents of an NSArray. One reason could be that you want to put the contents of an NSArray in to a table view, but in a different order to what is currently in the NSArray. This tutorial shows one way (of many) of how this can be done.

The method we will look at in this tutorial is the sortedArrayUsingComparator: which is an instance method from the NSArray class. On first looks, this can look a little complicated, but if you take time to read through and see what is happening, it begins to make perfect sense. It also makes for quite clean code too.

arrayOfObjects = [arrayOfObjects sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        
    }];

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