Author: admin

Tutorial: iOS Photo Slider View

This is an effective image slider that you can use to show your users multiple images inside a single window. This the user can swipe the Photo Slider or use the UIPageControl to change the current image.

Tutorial:

Start with an empty single application template. First, we put a UIView into the UIViewController in the main storyboard file. This UIView will become our Photo Slider. It needs to be constrained to the center of the UIViewController, have an aspect ratio of 1:1 and bound to the horizontal edges.

Then we want to make our custom photo slider view. We need to create the XIB and swift file for this view. The XIB will look something like this, with a UIScrollView, UIView for our content and a UIPageControl.

Now we want to create the PhotoSliderView.swift file. This is going allow us to configure our slider with as many images as we want. It will also be responsible for handling the tap event on the UIPageControl, allowing the user to tap it to change the picture. Most of the magic happens inside the configure method. This is where we will iterate through the images that we are passed and add a UIImageView to the correct frame.

https://gist.github.com/rtking1993/6990bb1a3220cc023ad62cf46e967404

We need to call the configure method in the UIViewController. We have defined an array of six images, which we pass into the configure method. We are going to call this configure method inside of viewDidAppear so that we are sure of the photo sliders frame before we start manipulating the frames inside the photoSliderView. If we try to do this inside viewDidLoad, we could get unexpected behavior.

The last thing we need to do is set up our outlet in the main ViewController and don’t forget to change your UIView class to the PhotoSliderView. Now it is time to build and run and you should see a great result.

The full source code for a test project I have created for creating this photo slider is available:

https://github.com/rtking1993/PhotoSlider

March 21, 2018
Tutorial: Improving your animations with UIViewAnimationOptions

Animations can add a lot of magic to your application. They can be used to impress your users with great effects and give important user feedback to encourage a positive behavior. Creating animations using the Apple supplied UIView API is quite easy and by using UIViewAnimationOptions correctly, you can either create or improve the animations in your app.

You might be familiar with the UIView animation API. However one of the lesser used parts of this API is including the UIViewAnimationOptions. This allows you to improve the realism of your animations. These options change the animations time over progress ratio. By doing this, objects accelerate or decelerate whilst animating. This is important because, in the real world, objects do not start and stop instantly and do require time to speed up and slow down. Here is a diagram which shows two of the options. EaseIn starts the animation slowly and accelerates the progress, while EaseOut starts the animation quickly and decelerates the progress.

Tutorial

Start off with a simple single page application template. Set yourself up three cars (all at the same Y position origin) and a race button above the vehicles. The labels above the vehicles and the red finish line are optional.

Then we want to create the necessary outlets for the cars and their top constraints. It is very important that the outlets to the constraints are correct, as these are the constraints that will be manipulated in the animation block.

Now we should be ready to start animating our outlets. I have created some constants within the UIViewController, to help simplify the animation code. You can do the same if you wish.

Our animation code is going to sit entirely within our IBAction method. It’s a good idea to keep your IBActions as short as possible. However, because this is a simple demo I will make an exception. When we press the “Race” button, the top constraints for the cars will be modified to the position needed to help them cross the finish line. The cars will be animated for the same length of time and cover the same distance, but each in a different way according to their UIViewAnimationOptions.

Modify your constraint constant and call layoutIfNeeded inside the animation block, this will use Auto-Layout to perform the animation. Note that it is best practice to call layoutIfNeeded function before the animation block as well to ensure that all pending layout operations have been completed.

https://gist.github.com/rtking1993/a7b9b24cec94ee50cc4d8a2d6c68c617

Here is the full source code for the project:

https://github.com/rtking1993/UIViewAnimationOptions

March 14, 2018
Tutorial: Creating a UIImagePickerController

Taking and sharing photos is an important feature of many apps. Using the UIImagePickerViewController is a simple and easy way of enabling your user to either take a new photo or get an existing one from the user’s photo library.

Tutorial:

First of all, we want to start a new single application template project. We want to set up our main view controller, with the main image view, camera and library button.

Then we want to add an important string to our info.plist. We need to add an NSCameraUsageDescription so that we can access the devices’ camera. This is a small sentence that describes to the user why your app requires access to the camera. My sentence is only an example, you can replace it with any description you’d like.

Then we have to implement the code within our UIViewController to handle the button presses, present the UIImagePickerViewController and then handle the UIImagePickerViewControllerDelegate.

https://gist.github.com/rtking1993/a402e3b4e217a34bc44003f55f7c3f97

Here is the full source code for the project:

https://github.com/rtking1993/UIImagePickerViewController

March 7, 2018