Category Archives: Programming

Installing Octave 4.2.1 on macOS Sierra

I’ve been using version 4.0.3 of Octave for some time, installed via the binary available from SourceForge. It works reasonably well, with the exception of having to return to Terminal to enter commands for paged output. I wanted to move up to the current version and managed to get version 4.2.1 installed using HomeBrew. In case you are interested, here are the steps I followed:

  1. Open Terminal
  2. Enter the command: /usr/bin/ruby -e “$(curl -fsSL”
  3. Press RETURN
  4. Install homebrew/science using the following command: brew tap homebrew/science
  5. Octave requires XQuartz, install using: brew cask install XQuartz
  6. Install Octave using the following command: brew install octave
  7. Wait for a bit, then installation finishes

At this point, I “cd’ed” to the bin directory and attempted to run Octave with the following command:

cd /usr/local/Cellar/octave/4.2.1_2/bin/

Sadly, this produced the following error:

dyld: Library not loaded: /usr/local/opt/hdf5/lib/libhdf5.100.dylib
  Referenced from: /usr/local/Cellar/octave/4.2.1_2/libexec/octave/4.2.1/exec/x86_64-apple-darwin16.5.0/octave-gui
  Reason: image not found
octave exited with signal 6

After some poking around Brew’s install of Octave, I noticed the library in question (located at: /usr/local/opt/hdf5/lib/) had been updated to version 101 (libhdf5.101.dylib), instead of the expected 100 version. I also noticed there was a symlink from libhdf5.dylib to libhdf5.101.dylib. So I just duplicated that symlink, renamed it libhdf5.100.dylib and reran the ./octave command. Everything works!


P.S. I made a small text file that contains the following:

# Runs Octave 4.2.1


and saved it to the Desktop with the filename Octave.command. Then in Terminal, I made it executable by running the following: chmod +x Octave.command

You can now double-click this file to run Octave!

Setting a UIButton’s Image in Swift

yourButton.ImageView?.image is a READ-ONLY property!!!
yourButton.ImageView?.image is a READ-ONLY property!!!
yourButton.ImageView?.image is a READ-ONLY property!!!
yourButton.ImageView?.image is a READ-ONLY property!!!
yourButton.ImageView?.image is a READ-ONLY property!!!

yourButton.setImage(UIImage(named: “name_of_image”), forState: UIControlState.Normal)

OpenMP Clang in Xcode

I’ve been playing around with prime numbers recently, which (naturally?) extended into an investigation into parallel programming. I installed the latest version of GCC 5 (v5.3.0 at the time of writing) using these instructions and got OpenMP running (support is built-in). I’m fine with using Terminal but I thought it would be interesting to try this in Xcode.

I installed the OpenMP C/C++ language extensions for Clang using homebrew with instructions from here. Unfortunately, I received the following error:

can't exec '/usr/local/bin/clang++-omp' (No such file or directory)

It turns out those instructions were missing a symlink that needs to be created. It’s as follows:

sudo ln -s /usr/local/bin/clang-omp++ /usr/local/bin/clang++-omp

Thanks to Stack Overflow for the “full” instructions. I can now build and run C++ parallelized code directly inside Xcode. I am finding a performance difference running the same code via the Terminal vs inside Xcode (which is slower). Hmm…

UITextView Padding

If you align a UITextView with another element, particularly a UILabel, using Auto Layout you will notice the text in the UITextView is slightly indented. The UITextView is actually implemented inside an NSTextContainer which has some padding around it. To remove this (left/right) padding, set the following property of the UITextView to zero:

textView.textContainer.lineFragmentPadding = 0


Encoding a URL in iOS 9

The typical way to encode URLs (e.g. turn spaces into %20) was to use NSString’s


As you may have noticed, that method has been deprecated in iOS 9. You now need to use


which takes an NSCharacterSet as it’s argument. What NSCharacterSet am I supposed to use you may ask. I recently ran into this and found the following worked for me:

[NSCharacterSet URLFragmentAllowedCharacterSet]

The relevant Apple documentation can be found here.

Ctrl-drag to Create Outlets in Custom Views

If anyone can tell me why Xcode (I’m using Xcode 7 beta 5) works this way, I’d greatly appreciate. I have created custom table view cells in the past and I’ve always control-dragged from my storyboard into the custom class to create the outlets. So, when I went to create outlets for a custom (ui)view I’m working on, I was stumped when I couldn’t ctrl-drag into the .h or .m file to create them (outlets or actions).

[Yes, I have all the relevant custom classes specified in the Identity inspector.]

The workaround is to type in the outlet/action code by hand. Once you have entered in your custom class file, you can connect the outlets/actions by dragging from the little dot (do these things have a special name?) Xcode puts in the line number gutter to the relevant UI element. What a pain in the ass.


WordPress Menu Button on Mobile

A quick note regarding WordPress and its Menu button on mobile devices (mobile Safari for sure, others possibly). I’ve been trying to update this site a little and added a Books page to highlight the book I’m currently reading, along with books I’ve read over the last year. I decided to track the books using Pinterest and figured out how to post a Pin and a Board on a page. I decided I should check my handy work on my iPhone and quickly realized the “Menu” button didn’t work. Hmm…

As it turns out, WordPress updated the CSS tag used for the Menu button in their Twenty Twelve theme’s header.php file. So, if you have a child theme like I do and didn’t know about this update, your Menu button is no longer working.

Fortunately, it’s a very quick fix. Open the header.php in your child theme folder and replace the following line of code:

 <h3 class="menu-toggle"><?php _e( 'Menu', 'twentytwelve' ); ?></h3>


 <button class="menu-toggle"><?php _e( 'Menu', 'twentytwelve' ); ?></button>

The navigation.js file was (also) updated to look for this new tag, which is why <h3> doesn’t work anymore. That’s it, all should be working again.

Gesture Recognizers in iOS 9

I don’t code nearly as much as I’d like to, so keeping up-to-date is always a major challenge. I’m still trying to get up to speed on all the great iOS 8 updates with iOS 9 is right around the corner. So, this is probably not news to you but it was news to me.

Prior to iOS 9, you could have a gesture recognizer (GR) associated with 2 different views. You weren’t supposed to but you could. After wiring the GR to both views, you could add the UIGestureRecognizerDelegate method:

– (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch

return YES, and Bob was your uncle. If you do that in iOS 9, you get a very nice error message stating you were never supposed to do that, it’s now being enforced, and the GR will only be added to the view that first loads it. Having figured that out, okay, no biggie, I removed one of my views from all my GRs and then added “duplicate” GRs to the other view, named them differently so I knew which were which, and wired them to the same action method. All good to go.

P.S. Here’s the relevant Apple Documentation page. Scroll down to:

Gesture Recognizers Are Attached to a View

Every gesture recognizer is associated with one view. By contrast, a view can have multiple gesture recognizers, because a single view might respond to many different gestures. For a gesture recognizer to recognize touches that occur in a particular view, you must attach the gesture recognizer to that view. When a user touches that view, the gesture recognizer receives a message that a touch occurred before the view object does. As a result, the gesture recognizer can respond to touches on behalf of the view.

Creating a Transparent Modal UIViewController in iOS 8

I’ve just started to scratch the surface of all the cool things iOS 8 can do, so much to learn! One of my apps presents a modal view controller that asks the user to select a date from a custom calendar view I built. The app displays photos and this modal vc is presented over an image, so I wanted the modal vc to be (semi) transparent, so the image could be seen behind it. I scoured the web but there seemed to be a lot of conflicting ideas out there and none of them worked for me. I happened to stumble upon a/the solution on my own, while poking around Attributes Inspector.

Select the (modal’s – i.e. the one you want to be transparent) view controller from your storyboard and then click on the Attributes Inspector. As you can see in the screen shot below, there are Transition Style and Presentation options now available. The Transition Style is just what you expect it is and for Presentation, you want to select Over Current Context. Viola! Crazy simple.

Attributes Inspector

I’d be interested to hear what has worked for you in iOS 7, although backward compatibility is quickly becoming less interesting to me.