I have an app I made for Lion but I want it to run on Mac OS versions as low as 10.4

Question

I created an application for the latest version of Mac OS X (Lion). My application uses ARC. I would however like it to be able to run on earlier versions of OS X.

My xcode says the earliest deployment target I can go is 10.4

By setting it to 10.4 does that mean I have done all that is required for my application to run on earlier versions of the OS up to 10.4?

Any help would be awesome thanks

Answer 1

To put it in perspective, OS X 10.4 was released in 2005. The last security update for it was 2009.

I've been developing for the Mac for the last 10 years, and my rule of thumb is it's usually OK to target the current OS version and only the previous one. Maybe even just the current version, if there's a compelling reason (new API) or the public knows a new OS version is coming out soon.

Example: in Spring 2012 everyone knows that OS X 10.8 will be released in the Summer, so new products I'd develop just on 10.7 with an eye towards 10.8.

There are a few markets where you'd want to do anything different (education being one), but these are few, far between, and usually only apply to long standing products.

Answer 2

ARC isn't supported for OS X 10.4 or 10.5. ARC is supported on 10.6, but has some problems that are not present on 10.7 (see question on this site). This isn't a show-stopper, but you should be aware of it if you use weak references.

According to Chitika (source), based on web traffic as of November 2011, 94% of Mac users were using 10.5 or newer and 72% were using 10.6 or newer. Those who haven't upgraded to 10.6 are less likely to be paying customers.

In my experience, developing a Mac application against an older SDK generally works without a hitch, but if you don't have access to an older system then you should warn your users that your application is untested on older systems. This is an unfortunate reality for independent developers. For example,

This application has been tested and runs on OS X 10.7. It may also run on OS X 10.6 but it has not been tested. OS X 10.5 and earlier are not supported.

Answer 3

There are a ton of API differences between 10.4 and Lion. Without seeing your app I cannot say for sure, but I would expect that it would not work correctly on 10.4 without some major changes. My suggestion is to forget about 10.4. I would be surprised if even 1% of OS X users are still running it. Stick with 10.6+ and you should be fine.

Whatever you do, only support versions that you have the ability to test on. If you don't have the capability to test on 10.6 you might even consider just supporting 10.7. If you cannot test on all of your deployment targets then you are setting yourself up for some pain.