Parallax UITableView header with Auto Layout

I’ve been working on a thing at Shopify, where I implemented a header containing an image that has a parallax effect when scrolling up and expands when scrolling down.

This isn’t exactly a new thing, but I wanted to implement it using Auto Layout and couldn’t find any examples of this. It turns out it’s super simple, so I found some time tonight and created a demo project you can find the code on Github:

Parallax Auto Layout Demo

To achieve the effect, you simply add the image view inside a container view that gets clipped bounds. Using two NSLayoutContraints, you then set the height of the container view and the height of the image view.

A bit more work is required if you’re working with portrait and landscape images, but the effect is very simple to achieve.

RMSwipeTableViewCell – cell subclass with swipe functionality

RMSwipeTableViewCell is a drop-in UITableViewCell subclass that supports pan gestures as seen in apps such as Clear, Mailbox, Sparrow and many more. It includes a number of delegate callbacks to help you integrate it into any project as well as a number of properties for look and feel customization. Here’s a video where you can see it in action.

RMSwipeTableViewCell Screenshot

RMSwipeTableViewCell was part of an app I am working on but the feature never made it into the final release, so I decided to improve the class and extend it with additional functionality that will allow it to more easily be integrated into other projects.

RMSwipeTableViewCell is available on Github and includes a demo project:

Xcode code snippets and syncing

Earlier today I took some time to create a few more code snippets in Xcode for code I’ve been writing a lot of lately. I’ve never really seen or discussed these much with other developers, so I was wondering whether people actually use them – and to what extent? I know from my own experience that I don’t use them nearly enough, so I thought I’d write up a quick post on Xcode’s awesome Code Snippet Library.

The Code Snippet Library in Xcode is a great feature and a huge time saver – you’ll be doing yourself a favour by using it if you haven’t already! Ever noticed how when you start typing “init” Xcode will autosuggest the Objective-C init method? It does this because it’s a code snippet with a completion shortcut “init”. Same with “forin”, “dealloc” and many more built-in code snippets. Check each snippet’s completion shortcut in their edit mode.

Objective-C init method code snippet

Here’s a basic example of a “user” code snippet I have in my library:

UIAlertView boilerplate code snippet

I wrote up the code for a UIAlertView, highlighted the code and dragged it into the Code Snippet Library. The code snippet retains the parameter placeholders as well as your indentation (don’t worry about the indentation in the preview box such as in the example above, as long as it’s correct when used in your code). Now for the awesome part: Notice how I set the Completion Shortcut to “alertview” and the Completion Scope to “Code Expression”? Now, if I type alertview inside a method Xcode will auto-suggest this entire code snippet and I simple hit enter to use it and tab through the parameters to quickly setup a UIAlertView. Thanks Xcode <3

The Completion Scope is fairly important as it allows you to set the scope for when Xcode should auto-suggest your code snippet. If a code snippet is a method, set the scope as such and Xcode won’t auto-suggest that snippet if you’re inside a method. If you’re writing code for both OS X and iOS you can also set a specific platform for the code snippet so you’re not having your UIKit-specific code snippets suggested when you’re writing code for a Mac app.

Keeping your Code Snippet Library in sync

An hour ago, I tweeted about syncing Xcode Code Snippet Library with Xcode, which basically led me to writing up this blog post.

I’ve got my Macbook Pro at work and Mac Pro at home and often switch between the two. Unfortunately Xcode doesn’t have iCloud syncing – though what a nice feature this would be – so keeping your Code Snippet Library in sync could be a small pain. Enter symlinks.

Custom code snippets can be found in


Each code snippet is a plist file, which means adding or deleting code snippets on any machines won’t give you any issues (I believe it would in Xcode 3 because all snippets were saved into one file, which may have created some conflicts depending on the method used to sync).

Assuming you’re a Dropbox user*, you can use it to sync user Code Snippets between two or more machines. In the following example, I’ve setup a folder in Dropbox for Xcode. I’ll move my /CodeSnippet folder to the Xcode folder in Dropbox and setup a symlink in the original path that points to the CodeSnippet folder in my Dropbox:

$ cd ~/Library/Developer/Xcode/UserData
$ mv CodeSnippets /Dropbox/Xcode/
$ ln -s ~/Dropbox/Xcode/CodeSnippets/ CodeSnippets

You may have to sudo the last line, but now you should be all set. Do the same thing on your other machine(s) and start creating lots of useful snippets to use on any machine you’re working on! Don’t forget Completion Shortcuts to make your life much easier.

Hope you found this post useful. If you have similar tips, feel free to share in the comments. @tewha replied to my tweet saying that he uses symlinks to sync Archived builds and other Xcode User Data across several machines.

*If you’re not a Dropbox user, feel free to use my referral link :)

Making Rounded Rectangles Look Great (with CSS)

Go directly to the project demo page.

Mike Rundle of recently posted an article, Making Rounded Rectangles Look Great, on designing rounded rectangles, some design techniques, etc. I recommend you to check out the post and download the PSDs for great inspiration!

I’ve recently worked extensively with re-engineering and re-designing the UX and UI for an online retailer, which involved a lot of paper, Photoshop and CSS (or Sass).

I thought it would be cool to create the buttons from Mike Rundle’s article in pure CSS, so I went ahead and did it. Before checking out the CSS buttons, be sure to check out Mike Rundle’s examples and PSDs for a comparison.

I tried as much as possible to stick with the same colours and transparencies as Mike Rundle’s examples, although there may be slight differences, depending your display and browser.

I’ve also added :hover and :active states to all the buttons, so they’re a bit more exciting. Unfortunately CSS doesn’t provide a simple way to create a masked gradient at an angle, so the Convex example is probably the least similar one. But it still looks great and I wanted to stick with all CSS – could have been achieved with an image mask or simple overlay.

You can check out the result on a separate page. Feel free to grab this .zip containing all the project files:

Accessibility on iOS: Working with VoiceOver support

Accessibility on iOS provides visually impaired iOS users the ability to use an awesome touch screen platform to its full extent. It’s your job as an iOS developer to ensure your app works wonderfully with Accessibility on iOS.

When considering adding features or optimizing your app for Accessibility, don’t assume we’re just talking users who are completely blind. And despite being all iOS being full touch screen devices, there are lots of visually impaired users outthere, ranging from users who are blind, hard at seeing or colour blind, for example.

Apps, such as Mail, numerous Twitter clients and more include the possibility of changing text on the screen to a larger font size. Matt RixTrainyard includes an option for players who are colour blind. These are just a few examples of improving apps for Accessibility.

Also consider interaction. While a scroll requires just a flick with one finger for regular use, having VoiceOver enabled scrolling is done with a three finger swipe, and moves the UIScrollView (and any NSObjects that inherit from UIScrollView) a page at a time. So while a pull-to-refresh is awesome, for user with VoiceOver enabled, it might not be as apparent or ease to use.

In this post, I will focus a bit on optimizing your app for VoiceOver. Before continuing with this post, check the video below where a blind user shows off VoiceOver and demonstrates how to use it.

I also recommend enabling VoiceOver on your own device and playing around with it for a while, just to get familiar with it. One thing is to know about it and use it with the Accessibility debugger turned on in Simulator, another thing is to experience it for yourself!

While most of UIKit works fairly well out of the box with VoiceOver, there are plenty of things you can do to improve how your app works with VoiceOver. If you’re doing any custom UI (especially drawing) VoiceOver will most likely not work, or it may speak out the names of the object. So if you call a custom UIButton “createNewTaskButton,” that’s what it will say. Instead, it should probably say “Create New Task”.

Consider your own app(s) and what use visually impaired users may have of it. I made a transit app, so it was only natural to optimize it for visually impaired users and add custom and improved VoiceOver support. With VoiceOver enabled, users can tap the time until the next transit vehicle arrives and the device speaks out in plain English “Next TTC vehicles arrives in 5 minutes and 32 seconds. Tap again to hear updated time.” If I had not customized it, it would have just said “5:32.”

Underneath are subsequent vehicle arrival times. As you can see from the Simulator screenshot, without VoiceOver optimization, the device would just say “20 min bullet 25 min bullet 26 min.” With Voice Over optimization, it says “Subsequent TTC vehicles arrive in 15 minutes (pause) 20 minutes (pause) and 25 minutes. Tap again to hear updated times” Notice the (pause) and look at the screenshot. VoiceOver speaks pretty fast, so if you would like a bit of a pause, just insert a period, and it will pause a bit between the words. This is a great way to split up important information.

Also notice how it will say “and” for the last arrival time. If there are more or less times, it would only say it for the last item. Remember attention to detail in these cases. If someone was to tell you the information for what you touched on the screen, how would you best understand it? There’s a huge different between spoken language and UI. Keep this in mind!

For the buttons with which users can change a route, the label would look like this “506 • Carlton.” In this case, the literal VoiceOver sentence would be “506 bullet Carlton.” So I went ahead and customized this to “506 Carlton,” so it wouldn’t speak the “bullet” part of it. For the custom UIButton where the user can add or delete a route/stop selection to their Favourites, I added “This is a favourite. Double tap to remove from your favourites” and if the selection is not a favourite it would say “Not a favourite. Double tap to add to your favourites.”

If you’re doing any custom drawing, for example as I have done in the example on the right, you will need to pay extra attention to VoiceOver optimizations.

For flat, drawn views, VoiceOver cannot access any of the text or other information on screen. In this example, I draw each cell, so there are no UILabels or UIImageViews for VoiceOver to recognize and speak.

I therefore set the accessibilityLabel property on each cell which then provides VoiceOver with information about what to say. As you can see from the example, according to Accessibility Inspector, VoiceOver will say the route number and name, and because the item is a current selection, I also made sure VoiceOver lets the user know about this by saying “Current selection” after the route number and name.

For non-VoiceOver users, the checkmark is a great visual marker for the item being a current selection. But for VoiceOver users, this would have not been the case. Especially since it’s a custom drawn view, VoiceOver has no clue about the checkmark. In your Accessibility optimization, not only consider what VoiceOver would say, but also consider the UI and what VoiceOver can see, or should see that is related to the item the user it touching.The user may not know about a certain UI object or visual marker without VoiceOver telling them.

Accessibility Inspector in iOS Simulator is a great tool to help optimize your app for full VoiceOver support. Tapping the X button disables the Inspector and hides most of its UI. This enables you to see the app without VoiceOver enabled to quickly get to the content you’re currently debugging for VoiceOver, or since VoiceOver scrolling requires three fingers, it will allow you to scroll when you disable it temporarily.

While Accessibility Inspector shows what VoiceOver will say, you should again test on an actual device with VoiceOver enabled. As mentioned, one thing is how something looks and “sounds” when it’s written, another is how it sounds when VoiceOver speaks it.

So these were a few of the consideration I made for one of my apps in optimizing it for full VoiceOver support. For more on the subject, I urge you to read Apple’s Accessibility Programming Guide for iOS, which gives a more detailed overview of the possibilities as well as more in depth examples and usage guides.

Furthermore, Matt Gemmell has written a great post on it as well with more details on Accessibility properties, among other things, and it’s totally worth checking out.

Core Location presentation at TACOW

Last night, I did a presentation on Core Location for TACOW’s (Toronto Area Cocoa and WebObjects developers group) quarterly meet-up. I volunteered during a lunch with the group’s co-founders David (@rebeld) and Karl (@kolpanic) on the last day of WWDC.

I picked Core Location since I had learned some good insight at WWDC and also worked with the framework thoroughly through building my app Next TTC.

The presentation went well and was well-received, and I am now posting it here for everyone else to enjoy. I have left my notes in the presentation, but I am not sure how much help that will be. I suggest you view the presentation in Play mode, just so the animations help understand the content a bit better.

Download: Core Location Keynote presentation


ColorKit: A Color Assessment Utility App

For this week’s #idevblogaday post, I’ve written a small utility app that’s freely available for download on github.

ColorKit is a tiny iOS app (iPhone) which allows for quick and easy color-sampling for a UINavigationBar + UIToolBar. It allows developer to easily assess the appearance of tintColor on the device.

Last week, I talked about adding textures and depth in your app, in particular to a UINavigationBar. While this effect is great when used appropriately, UINavigationBar’s tintColor property is extremely handy and useful to give your app a unique look with one line of code.

Finding the right colour for your app can be a bit of a hassle, especially due to differences in colour appearance depending on which monitor or device you’re using. Furthermore, UINavigationBar and UIToolbar are coloured with a gradient and has a glossy shine, so knowing exactly which RGB value to use is often impossible.

ColorKit builds and runs right on your iPhone and makes it extremely easy to quickly play around with various RGB settings to find the perfect colour for your app.

Inside the app is a UIImageView which allows you to add a screenshot from your app to better see how the colours may look with your UI.

You can download a copy of the code here:

Pro-tip: Do not use bright colours. Play around with the values to create more “faded” colour. Brighter colour wash out the title text and generally look horrible.

Random tips

I was expecting this blog post to be about something completely different, but I’m still out of the country and have come down with a bad cold, so it’ll be a bit of a short and simple.

I’ve decided just to a few coding tips, I have come across and though might be useful for other devs, especially if you haven’t worked much with UIKit before in your development, or perhaps just these areas below. (At the bottom of this post is an Xcode project file which includes examples of the tips below).

Tip #1: Check for URL scheme and open correct app from your own
You’ll probably run into having to link to another app, for example your company’s Twitter account. Instead of just linking to the Twitter website, you can do a quick check in code and open the Twitter app instead. You can also do it with other Twitter client apps as well, however, not all have URL schemes setup (that I could find), and most users will probably be using the official one anyway. Regardless, the code is good to do the same check for other apps, or if doesn’t exists on the user’s device, you can try another Twitter client app, or use a UIAlertView to ask the user what else they’d like to use (depending on which ones are possible to open using the URL scheme).

Basically, all you have to do is ask whether UIApplication responds to the URL:

BOOL twitter = [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"twitter://user?screen_name=runmad"]];
if (!twitter) {
	[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@""]];
} else {
	[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"twitter://user?screen_name=runmad"]];

List of URL Schemes:

Tip #2: Getting a free UINavigationController in your UIViewController
I have seen some apps that use a UIToolbar as a navigation bar, and this just doesn’t work. If you compare the two, they’re actually a bit different, and this really shows when put in the wrong place.

If you’ve got a UIViewController, turning it into a UINavigationController is really easy:

RootViewController *rootViewController = [[RootViewController alloc] init];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[self.navigationController presentModalViewController:navigationController animated:YES];
[rootViewController release];
[navigationController release];

Tip #3: Getting a free UIToolbar in your UINavigationController
This one I only just recently found out (thanks to @auibrian)
. UINavigationController actually comes with a UIToolbar. It’s property is set to hidden:YES by default, so all you have to do is override this property when you load the view.

[self.navigationController setToolbarHidden:NO];

Note: I have seen some weird behaviour when pushing view controllers onto the screen (buttons not getting a pushing animation, just appearing in the toolbar in place). Also, you will need to hide the toolbar if you’re popping or pushing to a view controller that you do not want to show the toolbar (because with pushing you’re reusing the same navigation controller). In my opinion it’s not a very good way, I wish the view controllers were more separate for this.

Tip #4: Use shadowColor and shadowOffset appropriately when faking text indention
One thing that bugs me are improper use of a UILabel’s shadowColor and shadowOffset. When using these, one has to pay attention to the colour of the background as well as the text colour. In the below example (when we’re going for the look where text looks carved into the display, used by Apple across the entire UI), we’ll see that when using darker text, use a lighter colour for the shadow and a positive value for the offset.

When displaying lighter coloured text, use a darker shadow colour and a negative value for the offset, which in both cases create the proper indented or “carved” effect.

Using the wrong combination doesn’t create this effect and makes the text appear raised from the rest of your UI, which is most likely not what you should be going for in most cases ;)

I’ve made a small Xcode project you can download here, which has the code examples from tips 1, 2 and 3 and I suppose #4 as well, since navigationItem.title is using text indention.

Again, apologies for a bit of a short and simple post due to being under the weather and traveling.

Quick guide to updating your app’s UI for iPhone 4

iPhone 4 will make your UI look stunning. Everything in UIKit has been scaled up already so it will require only a bit of work on your end to make the rest of your app look amazing on iPhone 4. If you only code and don’t touch Photoshop, you’re in luck. However, if you’re a UI designer or have the skills to do your own UI, hopefully you did your original artwork in a nice high resolution – if not, you have a bit of work cut out for you with updating all the UI elements to 2x the resolution.

Updating your app’s UI to be compatible with iPhone 4’s Retina Display is amazingly simple. Since the scale works in points, not pixels, you will have to do very little work on the layout itself. Apple Engineers have made it really simple to use new graphics for all your UI on iPhone 4, at the same time as being compatible (and not using 2x memory) on older, lower resolution, lower memory devices.

All you have to do is add the same image file at 2x the pixels to your app’s resources and name it the same it’s lower resolutions sibling with the following suffix: “@2x”.

For example, in your Resources folder, you will now need to have two image files, one for older devices called myImage.png and one for iPhone 4 called myImage@2x.png, which is twice the resolution.

This way, when you call [UIImage imageNamed:@”myImage.png”]; (or contentsOfFile:) iPhone 4 will automatically grab the filename with a @2x suffix, and lower resolution images will grab the lower resolution copy. You don’t have to check for the device loading the image and write any additional code to grab the correct image. Genius!

If you have seen an iPhone app on the iPad in 2x scale, that’s pretty much how your app is going to look on the iPhone 4. Perhaps not so drastic, but there will be a noticeable difference from app not optimized for iPhone 4 and “Retina Apps” as Apple calls them.

Thoughts on @2x on iPad…
I didn’t hear anything at WWDC regarding this, but my thought is that they’ll integrate this into the iPad for the next major OS release. Basically, it will be able to do the same and grab the higher resolution image appropriately for iPhone apps running at 2x scale.

Happy Photoshopping to UI designers and happy relaxing programmers!

UPDATE JULY 7, 2010:

I have discovered a bug in Apple’s code that deals with grabbing the correct image on iPhone 4. If you are using imageWithContentsOfFile: the code will in fact not automatically grab the @2x if running on iPhone 4. I have submitted a bug report to Apple, and they’ve informed me they are now aware of the issue and the Engineers are currently working to fix the bug. So for now, stick with imageNamed: for all your images.

Debugging Executables for Push Notifications

I am implementing Push Notifications in one of my apps. Doing so may be a bit tricky in terms of debugging since you cannot actually debug incoming Push Notifications appropriately while the app is running, so I wanted to share this tip. Also, I am writing this post on my iPad on an airplane, so pretty excited about that :)

Xcode allows you to debug applications that are running locally on your device. You can even set breakpoints in your code and print out any information you may need from the console in order to debug your app and fix whatever issue you’re experiencing, should you not be able to fix it via “live” debugging.

This feature is especially useful if you’re doing Push Notifications (a great way to easily communicate information to your user with their permission, such as notifications, reminders, marketing (be careful with this one), etc.).

With Push Notifications, your app receives data from Apple Push Notification servers in a dictionary in the UIApplication delegate application:didFinishLaunchingWithOptions: that you’ll need to parse and do in your app whatever is appropriate for the implementation you’ve chosen (launching with specific views in front, etc.). Since your app cannot be running while receiving Push Notifications (it actually does receive notifications while running, but you’re required to deal with that through another delegate method), you’ll need to use the “debug executables” with “Wait for next launch/push notifications” ticked. Once you run the debugger and launch your app (for example directly via a Push Notifications UIAlertView) you can set breakpoints anywhere in your code and use the console to print out (po) any objects you may wish to inspect.

As your app launches immediately when you debug, it’s a problem if you’re debugging Push Notification (which, by the way, does not work in Simulator). So here’s the hidden treasure in Xcode: In the Groups & Folder pane, find Executables, expand and select your app executable. Hit command+option+i to “Get Info” and select the Debugging tab. From here, tick “Wait for next launch/push notification”.

Now, when you Run & Debug your app it will not launch, but instead wait until you tap the app icon to launch it or the app is launched via a Push Notification UIAlertView (this of course requires you have not set the “action-loc-key” to null in your Push Notification JSON dictionary).

Once your app launches via a Push Notification, it will stop at the breakpoint you set and you can now print out any information you need to debug your app, such as the NSDictionary your app receives, whether the appropriate view will be displayed and any other issue you may have.