Not sure why this is happening. I've set up a game in sprite kit using objective c and the code seems to work fine as I can see the nodes in the simulator - problem is that 4 times out of 5 the nodes don't show up- Then I stop and run again and it is running okay. Is there some simple reason for this? I have cleaned the program and it is still happening. No compiler errors showing in the code.
Are you using Xcode 7, testing on is9? if so it might be a bug with Apple's texture atlas.
Try using image.xcassets to create a texture atlas then load your images from there.