Top-notch video tutorials for Swift developers

In this episode we continue with our caching example, this time introducing a new type that will handle the caching for us, as well as wrapping the response type into a new type that will indicate to the view controller if the response was served from the cache or from the network. We end the episode by implementing Equatable so that our store can avoid needless double callbacks if the data has not changed.

In a recent project I leveraged the Codable protocol to save API responses to disk to make the application more responsive (and to have an offline mode). I was happy with the results. In this episode we will add some caching to an existing application, saving JSON responses to the caches directory on the device.

Codable is a great API, but sometimes real APIs can be tricky to model. In this episode we’ll examine a real use case of an API that returns a collection of elements, each of them similar but specified by a type. We’ll leverage Codable and inheritance to create a representation of this structure and show how you can peek into the container in order to determine what type to decode.

In this episode we extract our camera preview layer into its own view so we can add subviews. We’ll use this to add a flash button control to the UI, which will require us to learn about locking the device and controlling the camera’s "torch".

I got a tip from a subscriber about the method I used to capture the photo in the last episode. Since we're capturing the data using the preset we chose for processing the rectangles, we are bound to that preset when we export to an actual photo. By using AVCapturePhotoOutput, we can have much more control over the format, size, and quality of the resulting image. In addition, since we are leveraging the SDK for capturing the photo, we benefit from things like auto-flash, HDR, auto focus, and the built-in camera shutter sound. (Yay for deleting code!) The end result might not look very different on device, but if you are taking that image somewhere else to do OCR or other processing on it, a higher quality image is important.

Sometimes we need to create a quick icon and we don't have a designer handy. Usually in these situations I lean on icon packs like Parakeet Primaries or Glyphish. Lately I’ve needed some icons that aren’t available in packs like these, or the license isn’t suitable for what I want to use it for. In those situations I use Sketch to create icons myself. I’m no graphic designer, but I have found it helpful to know how to create basic things and export them for use in iOS projects. In this episode I design 2 icons that we’ll use in a future episode.

In this episode we take the captured image and run the perspective correction filter on it in order to turn a skewed rect back into a flat rectangle. We then display the image on the screen for a few seconds as a preview mechanism.

In this episode we implement features that make the app feel more like a camera. When tapping the screen, we play the system camera shutter sound using AudioServices, then we add a small but useful flash effect to reinforce the fact the user took a photo. We'll also talk about a strategy for capturing the image by using a flag.

We get smarter about drawing, this time leveraging a custom path so we can display non-rectangular outlines.

In the last episode it was clear our coordinate math was wrong. But why? We will answer that question and solve the problem. We also add code to hide the box if it hasn’t detected a rectangle for a few seconds.

We learn how to convert a CMSampleBuffer into a CIImage and how to set up our CIDetector to detect rectangles. We then draw a box around the detected rectangle and discuss why adding simple subviews won't work with full screen sublayers.

We set up the preview layer so we can see the video, then we add a sample buffer queue so we can get access to the individual frames of the video coming through the capture session.

We start by setting up the project to take photos. We start by disabling rotation, which is typical of a camera app. We then add the appropriate Info.plist entry so that we can inform the user why we need camera access. We organize the view controller intro sections to keep things tidy as we add code to the project. Finally we setup the camera capture session, which is the first step to capturing video from the camera.

In this introductory episode I show the finished version of the application we will be building in this series.

Core Graphics is a cross-platform technology, but there are some gotchas to consider when working on mac apps with AppKit. Sam will go over some of these differences to help you avoid some common pitfalls.

In this episode we’ll learn how to draw images with core graphics, then watermark a photo by drawing text overlaid on top of it.

In this episode we’ll leverage what we've learned to create a reusable control that will show progress as a path outlining a circle, complete with animation.

In this video we’ll learn how to use custom drawing with CALayers to support implicit animations.

Occasionally you will want to do some custom drawing, but not have that presented directly on the screen. Sometimes this is to "bake" the drawing into an image for faster scrolling performance (a single flattened image can be sent to the GPU easily without having to composite a bunch of views together). This is also often used to resize images that are too large for the intended view. This episode covers drawing to a custom context offscreen and obtaining an image out of it.

In this episode, Sam shows how to draw text using Core Graphics. With this technique you can easily add text to images for pre-rendering, a technique we will see in another episode in this series.

Sam shows how to use Core Graphics to draw images, which you might want to do if you want to blend techniques we’ve seen so far, such as clipping paths or gradients. Drawing images with Core Graphics is also useful to resize images if needed (perhaps if the API is returning one that is too large and you want to cache a thumbnail on device). You’ll also learn about a handy function to help you with aspect ratio math!

Transforms allow you to draw things rotated, moved, or scaled differently than you specified. You can use this technique to reuse drawing operations where they only differ by some small factor (like drawing lines on a graph), to tilt things like text, or to correct issues where the drawn element is upside down or sideways. In this episode, Sam shares a helpful technique of drawing a grid with a highlighted "origin square" to make it obvious what the transforms are doing.

Clipping paths allow you to control where drawing occurs by providing a path in which to limit future drawing operations. Since you can create arbitrary shapes with CGMutablePath (and UIBezierPath) this can be an essential technique to get the drawing effect in some situations.

Gradients are slowly returning to be part of the common iOS design aesthetic once again (after iOS 7 introduced an entirely flat design paradigm). Subtle gradients can be used to create interesting designs, provide necessary contrast for drawing text on top of photos, and provide a realistic feel to custom controls. Learn how to create linear and radial gradients, how to define custom locations to control the position and "shape" of the gradient.