问题
When you apply a number of Core Image filters to an image, memory can quickly become a limiting factor (and often leading to a crash of the application). I was therefore wondering what a good approach is to add one filter at a time and wait for each operation to complete.
The example that I am working on involves one photo to which the user can apply various effects/filters. The user is presented with a small thumbnail to get an idea of what each filter looks like. When all the filters are applied at one, the application runs out of its assigned amount of memory and crashes.
In short, how do I go about applying one filter at a time and be notified when the operation is complete so I can apply the next filter to the next thumbnail?
来源：https://stackoverflow.com/questions/9748220/how-to-apply-core-image-filters-one-at-a-time-to-save-memory-consumption