While testing and debugging your app with XCode you can use this logMemUsage() function to NSLog the used/free space and watch how things are going while you test your app. This function logs any change in usage > 100kb. It outputs to the debug log like this (on the simulator the free space is huge): 2011-11-02 21:55:58.928 hello[971:207] Memory used 21884.9 (+21885), free 1838366.8 kb 2011-11-02