I can put files into Assets.xcassets
or I can put files into folder references (the blue folders). When would I choose one over the other?
You should use Assets. Many benefits the folder references can't do
1) Change color of image without any code
2) Support vector, pdf better.
3) Support Slicing image
.
4) Manage resource easier for autolayout. If your resources has 1x, 2x, 3x and ipad image size != iphone image size
, you can add 6 files into 1 asset item.
You can read more here http://krakendev.io/blog/4-xcode-asset-catalog-secrets-you-need-to-know