The impact of a larger iPhone

It’s that time of year when speculation begins on whether the next iPhone, let’s call it the iPhone 6, will have a larger screen that the current crop of devices.
Apple are the only major phone manufacture that does not offer a larger screen. Until now this has not effected their sales, but there is quite a considerable market out there waiting for a large format iPhone from Apple. It must be only a matter of time before they do.
So if they do, what size screen will they release, but more importantly what will the resolution be?
Previous and current phones
Apple has already changed the iPhone’s screen resolution or aspect ratio twice.
The original iPhone that shipped in 2007 had a screen resolution of  320 x 480 pixels at 163 pixels per inch. The first transition was when Apple introduced the retina display with the iPhone 4. Apple had quite a few options when designing this phone. They opted to keep the screen the same physical size, with the same aspect ratio as the first iPhone but instead doubled the number of pixels in each axis, thus giving the iPhone 4 a resolution of 640 x 960 pixels at 326 pixels per inch.
The reason they opted for this was mainly to make life easier for developers. By keeping the same physical dimensions as the original iPhone, all apps would run unchanged on the new screen. Every object would appear in the same location no matter which device it ran on. The only ‘upgrade’ to the app the developer needed to do was to supply any artwork at twice the previous resolution so it would look crisp on the higher ppi screen, apart from that, the apps ran unmodified.
Life got slightly interesting for developers when they introduced the iPhone 5. Here they decided to change the form factor of the screen. Physically it was the same width as all previous iPhones, but had now grown in height. Its resolution was now 640 x 1136 pixels at 326 ppi.
So what did this mean for developers?
Well the width of any app was not an issue but the height was. The iPhone 5 had an extra 176 pixels in height. Apple quite correctly did not stretch existing apps to fill this extra space. What they chose to do was to run older style apps letterboxed. This extra height was blacked out and the apps ran at the same size as they would have on the smaller iPhone 4.
Thus we still had backward compatibility with older apps. When the developer updated their app, they could  then decide what do with the extra space. Some made screen elements slightly bigger to fill the extra space, some added additional functionality or move items around to fill the space. So the iPhone 5 was the first time Apple changed the aspect ratio of the iPhone. Apple have given the developers  quite a few new tools to help them write apps that are almost resolution independent, including a really nice tool called AutoLayout.
The Future
So assuming Apple does introduce a larger iPhone this year what will they do? There are several ways they could go.

  • One option is that they keep the existing resolution of 640 x 1136 but just scale the physical size of the screen up accordingly. Maybe 4.5 or 4.8 inches. The benefit for developers would be enormous. Because the aspect ratio and resolution would not change, their apps would run unmodified.This is in fact what we get between the iPad Mini and Pad Air, they both run at the same resolution but the Mini has a higher pixels per inch count than the Air. This approach would work fine.The downside though might be with the marketing.
    By increasing the physical size but keeping the resolution constant, the pixels per inch would drop from 326 ppi to around 260 ppi. This is a what happens with the iPads but this might be a hard stat to sell.
  • The second option is that they make the phone bigger and change the resolution. The simplest option for developers would be to do the same trick that the retina screens did, which is you proportionally increase the resolution of each axis.So the retina iPhone 4 used a 2x  scaling, the new phone could use either a 3x or 4x scaling.If 3x was used this would give us a resolution of 960 x 1704, with 4x we get a whopping 1280 x 2272.Again for developers this is a good option. Because we have the same aspect ratio, all apps would run unmodified apart from having to supply even larger versions of their artwork to make use of the high resolution display.
    However, for the phone itself, there would be one downside, these screen would run at 400-500 pixels per inch. This would have a large impact on battery life and the GPU. Also, beyond 300 pixels per inch, I doubt anyone could seriously notice the difference in quality.
  • The final option is that they go for a completely new and different screen size, aspect ratio and resolution. For Apple this would give them more options in how the final phone looked, no legacy. For developers this is the worst case scenario.Unless their apps were using the latest technologies, such as AutoLayout, their app would not run correctly, and even with this technology there is no guarantee all would be OK.
    Again, Apple could repeat the trick of letterboxing older apps on both axis until they where updated. Would Apple do this? Of course they would. Would developers like it? Nope,  but they would have no choice.

The other thing to think about is – what do you want from a bigger phone? You can either choose to see more on the screen or  to see the same amount of content but everything is physically larger. So far Apple have gone down the route of showing the same content but making it larger on the bigger devices. Personally, I would like to see more content but I suspect Apple will keep the status quo.
So we may get a larger iPhone this year. If so, my children will not eat for a few months, but equally Apple could decide the current size is optimal.
It should be an interesting year. We should get our first hints of what is coming at this year’s World Wide Developer Conference in June. Here Apple will announce any new OS’s which may give us a clue in the direction Apple is going.