How to remove subviews to release more memory

I have UIScro开发者_C百科llView with number of subviews. Each subview is custom UIButton with UIImage. When I load more and more subviews, more and more memory is used. But I remove invisible subviews by removeFromSuperView method. Subviews are removed and stay invisible, but Im afraid that no memory is released. UIImage is image downloaded from internet. Thanx for help.

use clear cache concept for this. for more https://github.com/thest1/LazyList.