How can I accurately describe text and image sizes for our iOS developers?

Question

I'm having trouble being able to articulate the correct sizes for text and other visual elements to our iOS developers. I understand that when building an app they don't use PX as a unit of measurement, but PTs.

I design my comps using static PSDs at 640x1136. I've looked around at various blogs and most people are saying that the PX size should generally be equal to the PT size in development. But 32px isn't matching up.

Perhaps it's my workflow which needs changing, which I am completely 100% open to.

Any ideas? Can anyone provide any more guidance?

EDIT: Just to clarify, I have no experience with the actual build of an app so i'm not sure whether there are technical issues around units of measurement.

Answer 1

It would appear your team has a communication problem on their hands. That said I would suggest you possibly integrate a meeting PRIOR to development. Since this is one sided I will suggest a variety of workflow methods that you should possibly consider if the communication is broken for the team.

• Project sit down - before a design -> development scenario I would suggest if the level of communication is breaking in the design, ask. That doesn't mean approach with a rant of my "designs aren't correct!" to the developers because you will only irritate them and it doesn't solve anything.
• Pixel perfection - Just to make sure you are aware there will ALWAYS be some deviation from the design in software to the actual code. This is a great example of why many, including myself, pitch for designing in the browser. In your instance you could simply create a HTML5 document with a viewport set to the size of the device you are developing for. There are even some tools that can modify your browser, wether Google or Firefox, for a device.
• Blueprint - If you are in the design phase and I would surely think for repetitive tasks you have either created a template or scripts to execute a common norm for handing off your design to development. If there's a breakdown then in your team create a blueprint with the measurements laid out and present them in your meeting.
• Consistency - I would hope you aren't handing them scattered designs. Review how you're sending design to them for development.
• Development iteration/revision - Create a revision control system by separating the development into phases:
  • App frame with just the background
  • Navigation
  • Image location if heavy on images
  • Animations or functionality

Answer 2

Points and pixels are often the same, but not always. Many Apple products, (including the iPhone and most iPads) operate at HIDPI, which means that the pixel density is much higher than standard displays. The iPhone needs double the pixels to display a particular point size, which means that if you are working at 640x1136 with a 1:1 points to pixel ratio, then a 24px font on your screen would also use 24px on the iPhone, but it would have a point size of 12.

That said, the developers should definitely be able to tell the difference between 12px and 24px and choose the correct point size on their own. If you understand the technical differences and this is really just a communication problem then in case I would take a look at Matt's answer.