Apple is so closed source you can't even make hardware that will work with their computers - let alone software. Microsoft is open up to allow for better integration, Apple will never do that.
See, here's the thing, everyone hates apple except those who wanted to be different and spent a fortune on something they believe is better. The spend the rest of their time convincing the world (and indirectly themselves) that they made a good investment.
If you look at the way apps make their way onto the iPhone you will see exactly why Apple is bad for open source, and infact any source - if they don't like it it won't work. There in lies their problem.