Sometimes it can be handy to either translate an address into a set of coordinates, or get an address from a set of coordinates. These processes are known as geocoding and reverse geocoding respectively. This quick tutorial will go over how to do these things using location services.
The view controllers of your application coordinate between your data and what is actually displayed on screen. In a well written MVC application the view controllers will be where much of your essential app logic lives and in turn where you will spend a lot of time. UIKit supplies many built-in view controllers and view controllers of view controllers such as UITabBarController or UINavigationController. With these you can accomplish an amazing amount of tasks, but sometimes you need or want something a bit more custom! This article will discuss a few helpful techniques for developing and working with custom view controllers.
Last time we left off in our block discussion I had gone over some of the basics of blocks. How to implement them, call them, and gave a bit of insight on why they are cool. Now, there is one really big benefit to using blocks and that is Grand Central Dispatch. There are of course many other neat things you can do with blocks and we’ll briefly cover a few of those too.
- You Have already looked at Recipe 25: Implementing Blocks Part I.
So What Is Grand Central Dispatch?
Today, I’ll use wikipedia as my crutch:
Grand Central Dispatch (GCD) is a technology developed by Apple Inc. to optimize application support for systems with multi-core processors and other symmetric multiprocessing systems.
Ok this doesn’t tell us a whole bunch, but what it does tell us is that it is a technology developed for multi-core processors. All you need to know is GCD is a set of tools that Apple has provided that allow us to perform blocks serially or concurrently on various queues (which map to either the main thread or another GCD managed thread). We also have the option of doing this either synchronously or asynchronously.
- You have strong knowledge of Objective-C and Core Foundation.
- You have basic understanding of of KVC (Key Value Coding) within the Objective-C language
Many if not all developers use collection objects everyday while developing great apps, but few know about the power of collection operators. As part of KVC (key value coding), collection operators help make many routine tasks simple by eliminating and simplifying code.
Those of you still waiting on the blocks part II article, hang in there, I’ll get to it soon enough. For now I thought I would give ya’ll something short and sweet that is also really useful.
Every now and then new stuff comes along that makes our lives easier. One of the best things to come to Objective-C is the advent of blocks. Blocks can simplify callbacks, enumeration, and they have huge benefits in terms of multi-threading. At first, blocks will blow your mind. Block syntax is weird, but once you get the hang of em’ they’re actually kinda easy.
This Recipe is inspired by a recent problem I ran into and had quite a bit of trouble with it. Basically I wanted to create a shape and fill it with a gradient. Sounds pretty easy huh? well, not quite as we’ll find out shortly. While my particular application required filling a circle with an ellipse, we can create any shape. In essence we’re creating a window (shaped however we want) where the user can see only a portion of the drawing behind it.
Working with Xcode can sometimes be a frustrating experience…
However, Xcode has a few times saving features that really make a difference in day to day development. In this post we are going to break from the traditional format in order to examine a few of these features.
Xcode snippets have gotten a bad wrap since they were introduced. This is mostly because they seem to lack some obvious features and are poorly documented. However, this doesn’t stop them from being an immensely powerful addition to Xcode. So let’s dive into using existing snippets and creating new ones.
One of the coolest things about the iPhone is it’s ability to handle audio. Since it was born out of an iPod, the iPhone handles audio quite well. In this recipe we’ll explore audio recording and playback. We’ll be creating a simple app that records a sound file and plays it back. We’re basically making a voice memo app that only saves one memo and plays it back.
- You’re familiar with UIAlertView.
- You have good understanding of the delegate pattern.
- You have at least heard of Blocks in Objective-C.
Have you ever found yourself wanting to present an alertView to the user to get simple yes or no feedback? If you’re anything like me you were very annoyed that you were required to implement the UIAlertView delegate protocol just to handle this simple task.
Is There A Better Way?
This week I thought I would have a bit of fun and explore image manipulation using Core Image. This sounds like it could be pretty tough, but Apple has actually made this very easy. In this Recipe we’ll be creating a photo filter app that will let you choose a photo or take a photo using the camera and filter it.
- You know the basics of Xcode, If not, we got you covered: Familiarizing Yourself With Xcode
- You know how to create outlets and actions using the interace builder
- You have a developer account and can run this app on hardware, This will be necessary if you want to capture an image using the camera
Setting Up the Project
Setting Up the Framework
Go ahead and start with a single view controller application using storyboards and title it “ImageFilterApp”.
For this App we’ll need to use the Core Image framework. To add a framework select the top level project from the project navigator on the left and scroll down in the main window to “Linked Frameworks and Libraries”. Here you can press the “+” button to add the new framework. When the dialogue opens choose the “CoreImage.framework” and press the “Add” button.